Cycling Llama

Cycling Goals

2009-02-10T16:35:00.000-08:00

Inspired by Dan here are my cycling related goals for the next few years.

2009

Cycling Goals

At least 4 century rides

At least 1 longer ride (double century or 300k)

Help Charissa train for this year's MS150

Get back into proper cycling shape (i.e. lose 25 lbs)

Do at least 1 weekend tour with the whole family

Building Goals

Design and begin construction on carbon fiber recumbent (possibly along with Dan and maybe a couple others). Inspired by Malric

Design and build recumbent Trail-a-bike for Lexi

2010

Cycling Goals

Ride compete brevet series (on carbon bent)

Ride Pgh->DC tour with family (or large part of it anyway)

Building Goals

Complete carbon bike.

Someday

Ride across US (pref with at least 1 of my kids)

Ride a long brevet (1000 - 1400k)

Ride PBP and/or LEL

Tour the Pacific Northwest

Sometimes there are more important things than bicycles.

2008-07-21T08:50:00.000-07:00

So I've been off the bike for a few weeks and that will hopefully stretch into a few months. Long story very short, Charissa has had some pregnancy complications with our unborn son Levi. It's called Amniotic Band Syndrome (ABS) and basically the inner Amniotic membrane ruptures and shreds into these thin bands which can wrap around the baby and cause all sorts of problems. Levi has bands affecting both hands. We took a week long trip to Cincinnati to see specialists and have fetal surgery to repair what they could. The challenge now is just keeping the little guy cooking as long as we can. ABS pretty much guarantees a premature birth due to the membranes being compromised. More details and our account of the whole thing so far can be found here.

Your prayers are always appreciated.

-Tim

Century ride

2008-05-01T07:27:00.000-07:00

Last Sunday I joined Dan and Jim for most of Dan's proposed 200k+ ride. I should say upfront that this was an ambitious ride for me in a big way. Prior to this ride I had a total of about 260 miles on this bike and I would increase that by nearly 50% in a single ride. It is the longest ride I've done ever, and the first truly long ride I've done in several years. I was also riding with a couple guys who totally out class me in the fitness and base mileage departments. Jim rode PBP last year, and Dan has been training for a complete brevet series this year. Fortunately they are also really nice guys and were very encouraging. I appreciate that.

I started by riding down to the science center to meet Dan at 6am. I hit my highest speed to data on the way down Marshall at 48mph, but otherwise it was uneventful. We meandered out to Freeport road, crossing the river a couple times along the way. We met Jim at Trizilla and then stopped down the road at a GetGo for restrooms and last minute food selection. There was a bit of confusing following that since the road we had planned to take off of Freeport was closed, but Jim knows the area and was able to get us around without a hitch.

We started out with a short climb and then a nice long series of rolling hills as we passed through Rural Ridge and the surrounding areas. I was feeling good at this point and was probably pushing the hills a little harder than I should, a fact that would catch up to me later. This section ended at a nice downhill and then a moderate climb up Sun Mine road. As would be the pattern for the remainder of the ride, the guys vanished up the hill while I plodded along. Typically for the first half or so of the ride, they'd shoot uphill in front of me, and I'd catch up on the downhill and maybe pass... wash rinse repeat. I expected Jim to climb well as he was riding the lightest bike by probably almost 10 lbs and it's not a recumbent. What surprised me was how well Dan climbs on the p-38. Jim and Dan stayed together on just about every climb of the day.

We continued along until the first stop at about 40ish miles at a sheetz. This was welcome for me, I was starting to get a bit of toe numbness and I just really needed to walk around for a minute or two. I was also starting to feel that I was pushing a bit too hard on the hills and my knees were starting to complain a little.

We continued through Butler and north. Made a 5 mile wrong turn near one of teh Rt 8 crossings that took us through some gorgeous country through which we unfortunately had to back track. My knees were starting to make their complaints heard loud and clear at this point and I was getting worn out by the pace I was setting. We took another short pee break by the side of the road once we set ourselves right here.

Thus began the section that goes around the north edge of Moraine State park. IMHO this is some of the most beautiful country we encountered in the ride. It's also a series of unrelenting rollers that just trash your legs. I was starting to find a better pace for myself tho and that helped a lot. I just needed to climb at my own pace and use my aero advantage to try to catch up when the road went flat or down. We had hoped to stop for lunch at the Cooper Lake campground but it was closed. I stopped and popped a couple ibuprofen to calm the knees and we continued on. A few more rollers along Rt 19 and we stopped for lunch at a gas station with a subway.

I was looking forward to the long descent into Ellwood city at this point. A few more climbs later and we finally found it. A nice longish downhill run followed by several more miles of gradual altitude loss. This combined with lunch brought my energy levels back up nicely. I felt good as we rode river road and turned onto 588.
I was riding my own pace and not trying to keep up with the guys. I had no problems on the flats but once the climbs started I just let them roll out of sight and did my own thing. 588 has one moderately diffucult climb before you cross the turnpike for the first time. We made a quick stop at a gas station at the top. Then more rollers to brush creek road (which is REALLY nice) and onto 989. Jim made a stop at a kids lemonade stand which they thoughtfully set up for passing bikers.

At 989 and Lovi I decided to part company with the guys and go to my wife's Uncle's house in economy instead. I was still feeling good, but I knew I didn't have another 30 miles in my legs. I'd rather stop in good form than hit the wall. Unfortunately this decision meant riding up Dunlap Hill on 989 to get to Conway Wallrose. This hill is of the devil. It's narrow with no shoulders (well craters with loose gravel when you are lucky), it's probably about 12-14% ish in grade and is sustained for a while. Oh and you have pickup trucks doing 50mph about a foot off your left shoulder.... not my idea of a good time. Oh well, I got up it and rode down Conway Wallrose for a mile or so to Uncle David's house. Still feeling good.

Total distance: 111 miles
Average Speed: 14.0 mph

A few general observations: I need to just work with the speed profile of my bike. It's slower going up and faster going down. Trying to force it to do otherwise is just asking for problems. This hasn't been a problem for me until this ride for the simple reason that I've not ridden with anyone else for any significant distance.

The fact that I can jump on this bike with almost no base mileage and do more than a century without any real problems is remarkable. I would have been crying in pain on the side of the road at about mile 50 had I tried this on my df bike. The fact that I wound up with a respectable if not blazing average speed is equally remarkable. For city traffic and such this bike is fair. A bit worse than an upright in the nastiest conditions (potholes, mostly) but a fair performer. For real distance riding, I can't imagine ever going back to a traditional bike. There are still improvements I can make for the next bike (better frame stiffness, mesh seat perhaps...) but it will be a recumbent.

Sunday ride

2008-04-21T08:40:00.001-07:00

So I did my first longish ride on this bike. Check out the route. Overall things went well. Total distance 52 miles, average speed ended up being a pathetic 13.7mph, but there is a bit of a story to that.

I haven't ridden the montour trail at all in about 6 years, so I decided to give it a go. I poked about on google maps for a while and noticed that it intersected noblestown rd out in washington county. I've not ridden noblestown either, but it'll bring me back to the west end bridge... looks good to me.

The first 10 miles to get to the trail flew. Crossing Neville island I was pushing between 20 - 24 mph the whole way. The trail itself is predictably slow. The crushed limestone just sucks energy, and you are riding uphill the whole distance, albeit a very gradual one. There were the usual panoply of kids and families at the start of the trail. The crowds thinned out past Robinson, but the trail conditions also worsened. The climb between Robinson and 79 is long and fairly rough. (rough surface conditions, not rough climb) I was struggling to maintain 12 mph on much of it. Once you get to the plateau at the top the trail conditions get worse yet with a lot of rough gravel, mud, and loose sand. The recumbent is not the ideal platform for such conditions, but I managed. That also killed my averages a bit since I rode a couple miles alternating between 15 and 8 mph due to trail conditions.

Noblestown road on the other hand was a joy. It's a series of nice rollers with almost no traffic until you get close to Carnegie. The climb out of carnegie is long but not bad and there is another climb a few miles later that is about the same. The payoff is the long twisty downhill into the west end which is a lot of fun. You need to dogleg over onto Steuben to get around some construction leading into the west end circle, which I didn't mark on the map, but that's no big deal. Coming over the bridge I started to realize that I hadn't eaten anything on this ride, and that was perhaps unwise. I seem to have a "bonk" ride once a year and this was it.

The clever rider would have stopped at the mini mart at this point and replenished at least enough to get home in good form. I am not clever. Instead I continued on and bonked hard about halfway up brighton. I spent the next several miles watching my average drop from 14.5 mph down to a final count of 13.7. I was struggling to maintain 9mph on flat ground, and was climbing at about 30% of my normal speeds. When I finally got home I almost had to call my wife to help me unlock the garage because my hands were shaking so bad. Stupid, stupid stupid. I do know better. I've done this many times, I know I need to eat about once every 2 hours at a minimum.... oh well.

Overall it was a good ride. I won't do the trail again. It's very pretty, but it's just slow and grueling. Noblestown was a joy though so I'll need to figure out more routes that use it. The bike fealt good overall. I think I need to make a small foam wedge for the seat base since I was sliding down more than I'd like but otherwise it performed well. It just seems to be made for rolling hills and swoopy curves. Once my blood sugar returned to semi-normal levels the only discomfort I have is slightly sore legs.

Seat Building, Finished!

2008-04-14T08:31:00.001-07:00

Ok, picking up from where I left off. Once I had the reinforcement on the ribs complete, I needed to put on the final back layer. For this I ordered some knitted fiberglass when I was putting in my order for the epoxy. It's supposed to conform to curves better, and be somewhat stronger, than regular woven glass. It's also a heavier weight fabric than what I had in woven fabrics so I'd only need a single layer for the back. Well it's pretty cool looking stuff anyway.

It does drape reasonably well for such a heavy fabric which is nice. It still took a lot of work though to get it wet out and to lay well into all the compound curves on the back of the seat. This is a process that I think would be better done with a vacuum bag. I probably have 2-4 ounces of extra epoxy in the seat that wouldn't be there if I had a way to compress the material. The finished surface is fairly rough due to the stitching that holds it all together. Using it on a finished mold surface would also be preferable. Having said that I am impressed with this material.

The next step was to apply a couple pieces of reinforcement where the seat mounts would be. In retrospect I think this was totally unnecessary as the finished material is so sturdy. Better to overbuild than have something fail I suppose, particularly since this is really my first experience with the material. (I've prototyped a few ideas in the past with glass, but never followed through with anything)

So the question that plagued me at this point was, how do you accurately mount the seat mount hardware on a surface that curves in all directions. What I came up with was mounting the upper mounts on a threaded rod that is held perpendicular to a piece of square channel AL. The aluminum runs up the centerline of the seat (by eye). And the lower seat mounts are bolted to a block of wood the exact width that the plates are when mounted to the bike, with a cutout for the AL channel. The wood was all cut on the milling machine to ensure accuracy though good skill with a table saw and drill press would have worked fine too. I think the pictures explain it better than I just did. To actually attach the mounts, I used epoxy mixed with milled glass fibers to make a thick paste. I wet sanded (with plain epoxy) the aluminum first to ensure a good bond. I needed a lot of gap filling for the lower mounts since the seat curves so much there. Once that set up I riveted it as well.

I noticed that the knitted glass wasn't totally laminated in two spots on the inside of the rails. What I should have done was drill some small holes and inject epoxy to fill the space. What I actually did was a comedy of errors. I started by grinding off teh knitted glass layer and replacing it with a few layers of regular glass. This was a pain. The following morning I decided it wasn't curing fast enough so I put a hot light on it to speed things up. This worked... a little too well. I proceeded to discolor the epoxy pretty badly. Oh well. It's cured now and it seems strong. I'll just have to live with it. Lessons learned.

Later that day I added the rivets to the now complete seat mounts, and trimmed the seat to width (24cm). I then mounted it on the bike for the first time and sat it to determine where the lower edge should stop. I want to make the total length and shape one of the standard sizes of ventisit pads in the hope of ordering one this summer.

I then trimmed and sanded, and sanded... and sanded ... etc... the seat. A coat of a basic gloss black spray paint later plus some reflective paint on the top half of the seat and I was done! Well, I also had to cut a new seat pad.

Wheel Building

2008-04-09T19:25:00.000-07:00

So I am swapping out the rear wheel I've been using on the bike for the one from my mtb. It's a pretty decent quality wheel, LX hub laced to a Rhynolite rim. The problem is the rim. It's much too wide for the narrow tires I am running on this bike, so I need to swap the rim. I have a SUN CR-18 rim laying around that I bought on nashbar closeout a year or so ago for a couple dollars. I'm a huge CR-18 fan. They are reasonably light and totally bombproof. I've used rims from other makers and I feel that the CR-18 is equal to any, and costs a fraction. They aren't flashy or aero or anything, but they make a strong long lasting wheel that will take a beating. They also have the same ERD as the Rhynolite so no need to change spokes.

To make the swap, first I removed the casette. This is optional but I'm replacing it too, so it's just easier to do at the beginning. Next I took the new rim and taped it next to the old one with a few wraps of masking tape. I aligned the valve holes and made sure the spoke offsets were going the correct way. I then loosened all the spokes on the side with the new rim and moved them over one by one. I cleaned the spokes and lubed the nipples as I did this. I then went to the other side and started moving spokes over. Start by moving all the spokes that are crossed to the inside of the wheel, then doing the ones to the outside. As I moved the spokes I tightened the nipples so that there was about 2mm of thread showing.

Once all the spokes were moved, I untaped the now free rhynolite rim and set it aside and got to the business of tensioning and truing. I start by tightening all the nipples with a screwdriver so that they just cover the threads. I then went around the wheel tensioning the spokes. I did 2 rounds of 2 turns each for this one. That brought me close to a good tension on this wheel. Before truing I went around and brought all the spokes to even tension by pitch. I then started truing the wheel. I needed to do a fair bit of rounding for this one, the hub was basically off center by about 2 mm. Rounding always takes longer since you need to do up to half the spokes at a time. It also requires more turns to effect a change. I then trued the wheel before checking it for dish. The dish was pretty off (usually is on rear wheels), so I went around tightening the drive side spokes till it was dished properly. I just tightened rather than alternating tightening and loosening to bring the tension higher. I've built quite a few wheels with this rim type so I have a good feel for the tone the spoke should make when it's plucked at the right tension. This one needed to be brought up a little more, so I was favoring tightening.

Once I was happy with the dish, I did a rough truing then stress relieved the spokes by grabbing parallel pairs and squeezing as hard as I could all the way around the wheel a few times. Then I did a finish truing. I put a dial gauge on it, and I'm good within about 0.3mm. Good enough. Lastly I put the new cassette on. It's an 8 sp SRAM 11-28.

All told it took a couple hours working at a relaxed pace and explaining to my 7yo what I was doing.

Seat building part III

2008-04-08T18:52:00.000-07:00

So the next step in building the seat was to mark out the centerline. I had marked a rough centerline on the mold, but I wasn't too sure about it. So I pulled the set glass form off the mold and put it on the sling seat form and sat in it. I then had my lovely wife mark my spine location directly on the glass. I then put it back on the mold and used the string trick to draw the line.

From that line I marked out the edges of the ribs by marking out lines parallel to the centerline. I think the ribs are something like 6cm from center but I can't remember and I'm not running downstairs to measure right now. One of the things about my design is that the seat stay mounts have to go on the ribs rather than between them. To accommodate this I am going to leave flat sections on the ribs at those spots and the bulk them up with several layers of glass.

To create the ribs I ended up using blocks of pink foam cut and spray-mounted to the back of the seat. I started by ripping strips that were 2" wide by 1.5" tall. I then applied them by mitering them by hand and mounting them 1 x 1.

The next step in shaping them was to use a compass to scribe a line on both sides 1" high. I then used a hacksaw blade to trim the height to this line. I then shaped the foam as best I could using a surform plane and sand paper to a nice round cross section with tapered ends. The spray mount didn't work real well for this BTW, the blocks kept falling off and generally being a pain. If I do this again, I'm going to use epoxy or possibly just spray foam.

I then mixed up some fairing compound using glass bubbles and epoxy and used that to glue down any particularly recalcitrant blocks, fillet the join to the seat, and fill any gaps between blocks. This also didn't work as well as I'd have liked. It was difficult to put it where I wanted it and get it smooth. In the end its OK but not great. Also something I'd do differently next time.

I came back the next day when the filler set up and tried to smooth out the nasty bits using the surform, files, sandpaper, and various dremel attachments. In the end I found the wire wheel on the dremel to give the best control, but it was a pain and ate up the foam if I wasn't really careful. I did mess up a few spots, so I used spray foam to back fill them and then cut and smoothed it out. This worked reasonably well. The spray foam isn't totally consistent throughout, so there are some bubbly bits, but it's good enough to keep the glass in place. Finally a technique that shows some promise!

While the spray foam was setting, prior to trimming it, I cut up some fiberglass. I cut 4.5" wide strips to cover the ribs from a lighter glass (5oz I think). I also cut them on a 45deg bias to allow it to drape better. I cut a total of 6 strips, but I was only able to apply one layer tonight because I ran out of epoxy. Darn. I ordered some this morning expecting this to be a problem, but I won't have it till Thurs or Friday, so I'm stuck till then. Still, things are progressing. I discovered that the bottom of my epoxy container contains a lot of semi-hard gunk. I'm a little worried that the stuff might not be 100% good, so it's probably good that I'm getting new stuff. It seems to have hardened ok so I'm keeping my fingers crossed and we'll see how it goes.

Seat building part II

2008-04-06T07:25:00.000-07:00

Once the plaster set up for about 24 hours on the seat, I scribed a piece of plywood with the shape and made a set of plywood ribs/base. These both stabilize the plaster and give me an easy way to set it on a bench to work on it. To attach them I used two layers of burlap strips soaked in plaster, and just mushed them along the joint.

After that I took the whole assembly downstairs (much to the relief of my sainted wife) and flipped it onto the workbench. I added 3 or 4 (I can't remember, I think 3) more layers of burlap and plaster onto the back of the seat. I am using the mold as a male mold and so I need to account for some amount of seat pad thickness. 6 layers of burlap plus the finishing coats gives me about 1/2" of thickness. I figure this is a reasonable number once you factor in foam compression on the pad. In any case it should get me close enough it won't matter.

After the plaster set up overnight, I went back and started adding layers of drywall compound. I was both smoothing and evening the seat out. There were some odd low-spots and a slight twist to the whole thing which I attempted to correct with successive coats of the compound. The drywall compound is MUCH easier to work with than the plaster for smoothing coats. It stays nice and easy to work for a long time and lets you work at a relaxed pace. Unlike the plaster which is rather frantic. It's actually a very enjoyable process. I was in the throes of a nasty sinus infection while doing most of the drywall compound and I found it quite therapeutic to head down there and sculpt for an hour or so. The other nice thing about the DC over plaster is how easily it sands. I was able to get a very smooth finish very quickly. The drawback to DC is how slowly it sets. The plaster sets up in about an hour. The DC overnight. So it took several days to finish this step.

The last step before applying the glass was to mark a centerline. This was rather harder than I thought it would be. I didn't have the foresight to mark my spine location while the mold was still wet and I was actually sitting in the thing. So instead I just used a piece of string weighted at the ends and laid over the mold and moved it around until it visually looked like it was centered. It's not perfect, but it should be fine.

To apply the glass I started by measuring and cutting out pieces that were about 38"x13". The finished seat length will be somewhere around 35" and the width about 10", so this gives me a bit of wiggle room. I then covered the mold with plastic wrap. In retrospect I should have waxed it and used it directly since the plastic wrap slides around a bunch and is a bit of a pain, but that would have taken a lot longer. For the first layer of glass I weighed it and found it was about 100g. So I mixed 95g of resin with 25g of hardener (100:27 mix for my particular epoxy). I then laid out the glass and carefully applied the resin by pouring it on and brushing with a disposable brush. I applied each successive layer (total of 4) by applying it directly over the previous layer while wet, pressing it in by hand, and brushing more resin on to soak. In all I mixed a total of about 310g of resin and applied about 385g of glass. That's actually a little less resin than I'd ordinarily expect, but it looks good so I'm not concerned about it.

The next step is to build the stiffening ribs on the back of the seat. I'm still figuring out how to do this, so stay tuned.

Making a new seat

2008-03-31T11:08:00.000-07:00

So I've decided that I need to replace my seat. The shape just isn't in agreement with my anatomy. I think I need a somewhat more laid back chest position with a more gradual transition into the shoulder area. This will mean more work holding my head up, but I prefer that.

I decided to build the seat from fiberglass. I carefully weighed the options between carbon fiber, glass, and wood, and decided on glass for the simple reason that I already have about 3 yards of the stuff in the basement and thus won't need to order anything.

My general approach is to make a simple wooden frame and stretch fabric over it, then make a plaster mold of me sitting in the fabric seat. This should recreate a comfortable shape for me while allowing a lot of control over the position.

I started by using an adjustable seat mock up I made some time ago to decide on an approximate shape. I then pulled this shape off it by scribing a piece of plywood, and made a simple form from plywood to hold tensioned fabric. I added more lumbar curve to the form from what I had on the mock up because I expected that to collapse under weight more than other places on the seat. I also scribed a line about an inch smaller than the line I took from the hard seat to account for fabric stretch.

I covered the seat with several layers of scrap fabric until I got the right amount of strength and stiffness. Most of the fabric is either muslin or some other lightweight non-stretchy cotton fabric. A heavier fabric like canvas would be preferable and would require fewer layers, but this is all stuff I had around the house so it didn't cost me anything.

I had originally intended to saturate this fabric directly with plaster, but a test showed this wouldn't work well. So instead I covered it with plastic and saturated a few layers of burlap. Much furious mixing and spreading ensued, but with the help of my lovely wife, I was able to get everything in place, another layer of plastic over the plaster, and sit in it before the plaster set up too much. I hung out and watched some TV for an hour while sitting in my seat. And then carefully pulled myself up by using a sling I had pre-rigged from the ceiling (to avoid cracking the plaster) .

Tonight I'll add some stiffening ribs to the plaster and then tomorrow pull it from the "seat". After that I'll add some more layers of burlap to build up the thickness to account for a seat pad, and also give it more stability. Then pull the glass mold from it.

Adjustable Seat Concept

2008-03-28T08:03:00.000-07:00

So based on a thread at BROL as well as my own observations on climbing performance, I started thinking what it would take to make a seat that is adjustable on the fly. The idea here is that there was a study that showed that the optimal hip angle for power production is about 105 degrees. (I'll try to hunt down that study again... I should have bookmarked). But that relatively "closed" position is less than optimal for aerodynamics. Also torso angle has some impact as well. Plain and simple we are designed to do aerobic things upright not lying on our backs.

The drawback to that position is that (sans fairing) it's aerodynamically crap. So what would be great would be to have a bike/seat that you could adjust over a wide range on the fly to suit the conditions. A more upright seat for climbing, more laid back for flats/downhills/headwinds. Somewhere in between for traffic. etc. This gives the added benefit of allowing you to vary the muscles involved which should improve long term endurance similarly to an upright bike.

The requirements that I can see for this seat are as follows:

The hip joint to pedal distance must remain constant.
The shape of the seat must be comfortable and efficient in all positions
The adjustment range must be at least 30 degrees with multiple intermediate positions. (continuous adjustability is desirable though not required)
The seat must be able to be adjusted safely while riding.
The weight must not be significantly more than a nonadjustable seat (total seat weight should be in the 4lbs range or less)

To this end I am thinking of a hardshell carbon seat in 3 sections. The seatpan will be attached to the frame, the back rest will be supported by the frame by ratcheted stays, and the shoulder rest will be supported by connecting members that make a parallelogram with the seat back so that the angle to the ground remains constant. The following images show the general idea. They are not to scale and the lower pivot would probably need to move to keep the hip-pedal distance constant, but it shows the concept.

First 100 miles, some observations

2008-03-27T10:02:00.001-07:00

So I'm right around 100 miles on the bike now. Not sure of the exact distance since I didn't have a computer on the bike for the first few rides but it's around there somewhere.

No pics to show right now. I made a few mods to the seat to improve comfort. I made a cutout in the upper back area first. That only partially solved the battered vertebrae problem. It basically just moved it up to the vertebrae at the base of my neck. So I made a sort of u-shaped channel there by cutting out part of the seat and gluing on some of the previous cut out material to reinforce it. Looks decent and is a lot more comfortable.

I'm still not 100% happy with the seat. I think fundamentally the shoulder rest is just too steep for my anatomy. I may make my own seat from wood or carbon in the near future as a replacement. I'm still pleased that I went with this seat, and I'd recommend Ed's seats to anyone, but as with any hardshell it may or may not fit you ideally.

File this under lessons learned, but attach your seat pad with velcro not double stick tape. Then when you carry it on a car rack, take the pad off. That nice looking original pad is still out there somewhere... wish I knew where. I replaced it with a much rougher looking section of camping pad. The looks are worse, but it's actually more comfortable so I'm not that upset. Still tho....

Chain clearance around the rear fork is something of a problem. I get a bit of rub in the highest gear on the side of the chain stay, and a bit on the bottom in the lowest gear. The side rub is just something I'll live with. It's minor and doesn't feel like it's really dragging at all, but it makes a bit of noise which annoys me. The rub on the low gear can be corrected with either a smaller rear cog or a larger idler. One or both of which I'll do eventually.

Hills... hills are interesting. My first few rides on steep stuff (10%+) worried me since I was really struggling. Until I realized I wasn't shifting to my lowest gear in the back. Once I got that sorted out it's a lot better. Last night I went out and did one section of my commute that is an average of 15% with a max of something over 20%. I didn't have any problem putting power to the pedals, but balancing is really hard at those speeds. I can only turn the bars so far without whacking my shins which is a bit of a problem under 4mph. The hill also involves a 180 deg switchback which I had to get off the bike to navigate. I just couldn't figure out how to make the turn that slow with the limited turning ability. Going down it's not a problem since I can just straighten my inside leg and coast and turn as sharp as I like, but no such luck uphill. I'm still not up to my df speeds, but I'm not too far off and I'm still getting my legs. On moderate grades I'm about 2mph slower on average. On flatter and steeper grades I'm actually about the same as on the df. Flatter because the aerodynamics come into play more, steeper because I can't ride any slower than about 3-4mph so I have no choice.

Traffic... I'm still a bit nervous in traffic though it's getting better. Riding uphill is nerve wracking in traffic since I don't feel as in control of the bike as I want to be, so I'm worried about swerving into a car. Riding on the flats is ok, but I'm still not as comfortable handling the bike as on my df, so there is still some acclimation that needs to happen there.

Road conditions... Potholes freaking suck. Rough roads at speed downhill are just unpleasant. everything feels like it gets transmitted directly into my lungs and it almost feels like an asthma attack. It's pretty bad. Fortunately most roads aren't that rough. I'm thinking about putting a wider tire on the rear wheel to help offset the effect somewhat. For the next bike I'm thinking either rear suspension or maybe just not as direct a coupling to the seat.

Speed... generally pretty good. Flatland speed is comparable to my old DF speeds. That will climb as I get more miles on my legs I expect. The speed profile is different, even on the flats. It's really easy to cruise along at about 19 mph, but then 21 feels hard. On the df 19 was working a little harder but 21 didn't feel like as sharp of a jump. Overall I'd say that the bent gives the same speed for less effort across the board, but the curve is just different. The thing accelerates downhill very fast as would be expected.

Comfort... apart from the aforementioned seat issues and the general battering from road surface, quite good. I've not done any rides over 20 miles yet, so time will tell, but I'm at least reasonably pleased so far.

What's next... So what about the next bike? I have a lot of ideas floating around, so I'm going to start drawing things in cad and mocking up ideas. Wait and see :)

First (real) ride

2008-03-06T15:57:00.000-08:00

So after days of lousy weather, a brief but unpleasant illness, etc... I finally got a free half hour to do a couple loops around the park. Total ride distance is about 5.4 miles, I don't have a computer mounted yet so avg speed etc are all unknown.

Impressions:

I was quite wobbly at first but that subsided after about a mile. After that I was just a little wobbly.
The bike climbs a lot better than I expected. I expect I'm still a bit slower than on my regular upright bike, but I am also expending a lot of energy just learning to ride the thing still, so that should go away. Riding uphill in the lowest gear (22.4 gear inches) is kind of tough to balance, though by no means impossible. Anything above that is gravy. I have no fears about doing the climbs on my commute.
My butt got cold
The only seat discomfort I had was from where my spine sticks out a bit more on my upper back. Seems to dig into the seat more than is comfortable and really gets jarred on hard bumps and rough surfaces. I'm thinking of making a small cutout in the seat to relieve this. Otherwise it was very comfortable.
I really notice the sounds from the rear of the bike more than I'm used to. I can hear the rear drivetrain and the rear brake a lot. Not a bad thing, just noticeable.
I feel my upper quads / hip flexors a lot more than I'm used to. Part of the recumbent adaptation I expect.
Even on a day with few people out and about, I got a lot of stares and comments.
GOOD mirrors are a wonderful thing.

Overall, I'm very happy about how the bike looks and handles. I'll do the small seat cutout, and I still need to make a bag to carry stuff, but otherwise I think I can call this thing done. Here are a few pics.

It's done! (mostly)

2008-02-28T06:30:00.000-08:00

Whoop!

The bike is done with the exception of a couple minor things (hand grips, toeing in the front brake pads, and making a little cap for the top of the steerer extension to be specific)

I re-assembled everything over the last two nights. There are only a few changes from the original assembly. The first was swapping out the front brake for a different one. The one I was using originally was binding up funny so I took it apart and promptly lost half the balls in the thrust bearing. I really should know better but oh well. Instead of messing with it, I just stole the brake off my road bike for now, I've been meaning to modify the road bike to use cantilevers anyway. The second change is related. I ground the bottom of the drop bolt plate back a bit for a few extra mm of tire clearance. The final modification was the addition of a frame protector for where the chain runs close to the rear fork. It's just a piece of soda-can spray-mounted on and encouraged to stay there with zip ties.

Frame baking

2008-02-25T18:03:00.000-08:00

The frame is dry to the touch, so to accelerate the curing process, and hopefully beef up the durability as well, I'm baking the frame. There has actually been a lot of baking going on in our house today, though my wife's version is more tasty.

To actually provide the heat source I'm using some stage lights that my dad stores in my garage when he's not using them. seems to work pretty well.

paint

2008-02-24T18:11:00.000-08:00

I actually got a lot done this weekend despite most of it being used up prepping for parties, grocery shopping, chiseling ice off the stairs (I literally spent two hours with a hammer trying to remove 1.5" of solid ice from the front steps), etc.

I picked up a small sandblaster gun from harbour freight during the week. On Saturday I tried blasting with the glass media I got from HF but wasn't real satisfied with the results. On sunday I picked up some regular fine sand from Home Depot and that worked much better. It's still a long and somewhat laborious process but it gave me better surface prep on the welds and other awkward areas than I could have by hand sanding alone. One piece of advice. If you use one of these, wear both a full-face shield AND the most tight fitting safety goggles you can find. The face shield protects against direct eye-destroying hits, but you get grit EVERYWHERE. I still have a few glass bits in my eyes that got there by threading their way around the face shield and my normal glasses. Also wear a good respirator and do it outside away from everything.

Once I finished the sandblasting, I hand-sanded the whole frame to get a consistent texture. I then wiped it down with mineral spirits and let it dry. I wiped it down carefully with a tack cloth and then sprayed a coat of self etching primer.

I let that dry for a half hour and cleaned up a few drips and re-sprayed. Let dry for another half hour and then hit it with the color coat. I went with a green. The color choices were pretty limited and I thought this might look nice. Time will tell. I'll let that dry for a day or two and then bake it using some stage lights that I just happen to have laying around. (It always helps to have multiple esoteric hobbies I guess).

First Ride

2008-02-21T09:56:00.000-08:00

Ok, so a lot more progress since the last post. I finished all the brazing and metalwork on the bike, including the cablestops. I elected to configure the rear brake stop to allow for either V or regular canti brakes. This gives me more options, and also I have several sets of canti's just laying around and no spare sets of V's that aren't in use.

The other bit of metalworking I needed to do (albeit a very simple one) was make the drop bolt for the front brake. I was going to use a bmx U brake, but after installing it it just didn't have the right look. And by "the right look" I mean that it was literally twice as wide as the fork crown. It would have worked ok, but I'm very happy with the solution I have.

To make the drop bolt I just drilled two holes 15mm apart through a piece of 1/4" 6061-T6 aluminum. I also made a spacer by turning a piece of AL rod in the lathe and boring it out to 1/4" (the closest drill bit I had to 6mm) . The spacer is to help keep the bolt centered in the recessed hole on the back of the fork as well as spacing the drop bolt plate away from the fork enough for the nut that holds the brake in place to clear. If I didn't have a lathe, I would have just used a second Aluminum plate and countersunk the back of it to use a normal barrel nut to hold the brake on. To keep the bolt centered, I probably would have used a second barrel nut, drilled out so that the bolt could slide through it sans-threads.

I decided to go with a volae handlebar rather than the bacchetta one I was planning on originally. The volae has open ends above the hands to allow for bar-end mirrors. This let me go with MUCH cheaper mirrors which more than offset the extra $10 the volae bar cost. I also just like the look and feel of it.

Onto the seat. I decide to just go with black paint for the seat. I started by priming it with some white oil-based primer I had bought for the bathroom remodel. It gives a nice base, is obscenely durable, and sands nicely. It's a compelte pain to paint though. On top of that I used a bit of sandable spray primer, then several coats of black spraypaint. I'm happy with the looks, and it should be reasonably durable and easy to retouch if needed.

The seat pad is made from a layer of closed cell foam (think backpack straps/back panels) with a solid layer of funfoam covering it, and a second layer of funfoam with the chevron shapes cut out. I attached the white foam to the seat with carpet tape. It should be removable if I ever desperately need to, but it will be a pain. The foams are glued to each other with spray adhesive. My tests show that once dried this stuff is much stronger than the foam itself, so it should last well. Overall I'm very happy with how this came out. It looks sharp.

Next step was to build it up! I decided to go with a loose housing cable routing on the handlebars since it seems to produce nice curves and means less housing/cable. I like the look of it and am very happy with the shifting and braking. Everything is smooth. After the initial build I did have to take a few things apart and re-grind the rear brake attachment a little for some extra chain clearance, but it didn't prove to be a big deal. when I pull it apart for paint I'll probably take a hair more off since I'll ultimately be using a 32 tooth large cog in the rear and there is only a 30 on there now.

So the next step is to test ride it! I'll say this... it's weird. Like learning to ride a bike again. I know HOW it works, but all my hard earned muscle memory is practically useless since it's 90 degrees out of phase. Still I was able to start and stop and ride in a straight line within 5 minutes. I expect it'll take about 250 miles of practice before I'm willing to commute on it, but that will put be back riding to work not later than mid-april if all goes well, possibly earlier.

Overall I'm very happy with it.

Next step is paint. I was going to do more rides with it as a bare frame, but I have decided not to for 2 reasons. The first is that it's still winter here so the roads are wet and salted which isn't exactly good for bare steel. Also it's bloody awful out with temps all over the place from 0F to 40F and regular snow/freezing rain/ etc. I'll ride these conditions on my upright, but no way on a totally unfamiliar bike. I'll paint it now and if I do need to do any other changes/fixes to the frame I'll just have to deal with it then.

I picked up a sandblaster gun from harbour freight last night along with some glass shot. I'm going to hit it with this first to remove any remaining flux, surface rust, etc. I'll "wet sand" it with a solvent and steel wool. Then wipe it down really well with a solvent. I'll give it a primer and color coat using spraypaint. I may bake it using a simple temporary oven up to 200F for an hour or so to make the paint harder. I'm doing tests right now to see how well this will work so this is TBD. I don't expect a rattle can job to be stellar, but if I can make it last a year or so, that's good enough. Eventually I'll get it powder coated.

Final Order!

2008-02-05T06:02:00.000-08:00

Whoop! I just placed my (hopefully) final order to a few online retailers to get the remaining parts I need to complete this build.

What I ordered:

Remaining work to be done before I can test ride it:

Braze in the weld nut to hold the idler mount. I wasn't planning on doing this but I can't find a bolt with enough threading on it to mount it as I wished without cutting the threads myself. It's less hassle to braze in the nut.
Braze on the cable stops. At a minimum I need the one for the front derailleur. I also may put on one to allow me to use a cantilever brake. Still undecided on that. I probably won't bother putting any on otherwise at first and just run full-length housing. I may change my mind on that after the test ride but we'll see.
Make a mounting plate for the U-brake
Clean the chain I'm using (lightly used chain)
Assemble the thing.

Remaining work to be done after the test rides:

Final decision about any braze-ons
paint the frame
any final seat trimming
paint the seat
polish anything that needs it
Fix any problems revealed from the test rides
re-assemble

Getting close!

It's getting close!

2008-01-29T15:32:00.000-08:00

I've done a lot since the last post, so this is an attempt at catching up. Much of December was a loss as far as the bike was concerned. Though I did totally remodel 2 rooms in my house... so not a total loss I suppose. And it made my wife happy, which is always a good thing. First some shots of the current state of the thing...

The first thing I did was get the seat mounts done. These use a sliding plate system that is bolted to the sides of the maintube via brazed-in weld nuts, similar in idea to what volae uses. There are 4 holes in the tops of the plates that are tapped and allow gross adjustment of the seat, the slots allow fine adjustment. The mounts to the seat are just pieces of angle stock (actually taken from the bathroom remodel, they had been being used as trim around the radiator... really ugly). They are held on to the seat with small machine screws. The angle stock is tapped and I will also add nuts for extra holding/locking when I do the final assembly.

I also made the mounts for the "shoulder" attachments to the seat. The upper part of the telescoping tube that holds the seat up is made from 6061 T6 Aluminum, and the top part is made from Al rod that is crossdrilled, tapped, turned, and milled. I then bonded it into the top of the tube with JB-weld epoxy.

The idler mount is made simply from a piece of square steel tube that is crossdrilled for an 8mm bolt. it will be attached with nuts on either side. I still need to make chain keepers. I also need to find a slightly longer bolt as the threaded portion of the one shown is too short. The idler itself is from PowerOn cycling.

The steering column is attached to the fork steerer using a steerer extender that I found at the local recycled bikes place for a couple $ and then turned down on the lathe.

Alignment

2007-11-23T09:00:00.000-08:00

I think I need to describe how I'm using the jig to align the frame. It starts at the rear axle which is held by spacer blocks that hold it at 2" centered above the jig surface perpendicular to the centerline and level. I then use two spacer blocks to hold the maintube at 2.707" above the jig with side wings that hold it centered. I then just clamp the sidewings to clamp the tube.

The next step is to align the maintube so the headtube is perfectly vertical. To do this I use a piece of straight 5/8" rod. I then made a set of spacers for it by drilling a hole through a piece of wood and mounting it on the rod and turning it in the metal lathe. I made two spacers that press fit into the headtube out of oak to hold the rod. And a third out of pine that is exactly 2" in diameter as a reference at the top of the tube.

I locate the tube front to back by locating the front of the 5/8" rod at a mark I made on the jig. I rotate the tube to align it vertically by using a square and sliding it against the tube and then sweeping it back and forth against the spacer at the top of the rod so it scrapes evenly on both sides. I now know that I'm aligned to within a couple thou.

Yay! Headtube!

2007-11-21T06:43:00.000-08:00

So I have to say that nova rocks. I ordered a new HT on Friday, I was expecting it to take a week with the holiday and all. I got it on Monday! So yesterday I cut it to length, cut the hole in the frame, and brazed it in place. I am MUCH happier with the brazing on this one. I didn't cook the tube nearly as much. There is very little charred flux (as you can see on the first image). The cleaned up shot is just after hitting it with a wire wheel on the angle grinder. I think I'll leave it like that. I'm no pro yet, but I'm pretty happy with that braze.

I also brazed in the seat mounts and the rear cap plate the other day. The seat mounts got good penetration, I'm quite happy with them. There are a few slightly dry edges, but I'm confident I got good penetration deeper into the joint, I just should have pushed the brass in more all the way round. I was trying to be too tricky by pushing it at only the top and bottom and using the heat to pull it around. On the whole this worked pretty well, but I missed a few spots.

This is the cap at the end of the maintube. I just slip brazed it as it's only moderately structural. It provides some protection against collapsing the tube, but that shouldn't require much and a thin slip braze should be sufficient. I also think I built up a good inside fillet. I put a lot of brass into this joint and not much was left outside. I didn't lose any to the floor, so it has to be somewhere.

Things left to do

2007-11-20T07:36:00.000-08:00

Time to step back and put my thoughts in order. Here are the tasks I have left to do and some rough estimates on how long it's going to take me. These estimates are pretty rough, but I'm getting better at estimating my time.

Fit headtube - 4 hours

Rough cut frame with Dremel cutoff wheel
smooth out frame with Dremel drum
Final fit with die grinder and possibly file
Cut HT to length with lathe (2 cuts)
Mark HT for placement
Braze in HT
cleanup

Fit FD mount - 5 hours

Design miter on DeltaCad
Mark tube
Cut tube & test fit
mount AL box tube alignment piece
Final fit tube
make end-cap
cut tube to length
braze end-cap
mount tube to alignment piece
tack braze
finish braze
cleanup

Align tube on jig - 1/2 hour
Braze BB - 3 hours

make clamp from scraps of tubing, angle and rods
test fit alignment
make spacer piece
tack
finish braze
cleanup

make rear-stay connecting pieces - 2 hours

mark out
drill
rough cut
finish grind/file
tap(?)

make lower seat stays - 3 hours

drill relief hole
drill out stay
cut to length
cut end slot for dropout
fit dropout
braze dropout
fit pinch bolt
braze pinch bolt
cut slot
cleanup braze

finish chainstays - 4 hours

clamp to maintube
fit lower seat stay connecting piece
braze lower SS connecting piece
tack braze to maintube
finish braze to maintube
cleanup

Fit brake bosses - 3 hours

make jig
mount bosses in jig
braze
cleanup

Fit cable guides - 4 hours

make helper clamp
plan out cable runs
locate and mark locations
clamp and braze for each
cleanup

That should be about it for the frame. There are a few other tasks like the seat mounting plates and the tops of the seat stays. Not to mention paint. But that gets me pretty much done with the steel work. Total estimate is 28.5 hours remaining. I should be able to get this done by around Christmas, which would be a good thing. I should have it on the road, weather and finances permitting, sometime in February.

Starting over...

2007-11-18T06:50:00.000-08:00

In an earlier post I mentioned how my unwise use of a dremel tool with a burr caused a few nicks in the tubing around the seat mounts. Initially I wasn't worried about this, but the more I thought about it, the more it bothered me. I'm worried about stress risers and the loss of strength caused by the thinning of the tube. I ran some numbers based on assuming that the rest of the bike was perfectly rigid (obviously false) and hitting a 2" bump at 50 mph. Granted this was not an FEA approach or anything so sophisticated but it should give a nice upper bound.

I found that the maximum stress was right at the seat mount (no big shock there) and with the full wall thickness I was right at the limit of 4130 steel. Thinning the wall by .005" increased the stress by close to 200MPa which is WAY over the limit. Now I realize that these numbers are way high since it assumes that the rest of the bike is totally rigid, when in fact the tires take up a lot, the fork flexes, the wheel deforms slightly, etc. All of the above dramatically reduce the maximum stress. What the numbers do tell me is how much relative strength is lost by thinning the walls at that location.

Because of this I decided to put that frame aside and start on a new piece of tubing. Realistically the original would probably never fail, but this is my first frame and I just don't have the experience to make that call. I might finish the original frame yet for someone lighter and/or less aggressive than me. 50mph downhills are an everyday part of my commute.

The good thing about all of this is that I still have several pieces of tubing left and the only thing I needed to re-order was the headtube. I took the day off work on Friday and spent some time working on the bike. I am basically back up to my stopping point on the first frame. I'll go over the details in future posts.

Head Tube and Rear Fork progress

2007-11-13T16:10:00.000-08:00

I made a lot more progress in the last week. Again time has been short, but I got another good day in last weekend and have been getting more efficient otherwise. Overall I'm getting pretty good at joint cleanup and metal shaping. The head tube joint is VERY good, no wiggle at all. The BB is quite tight. It's perfectly parallel with the maintube and within about a degree on rotation just on the initial fitting. I'll sort out the rotation error when I do the final fit, but that's remarkably good for a first effort IMHO.

The thing I need the most work on is brazing. The joints are turning out ok, but not stellar. I roasted the headtube a bit. Note the charred flux. I'm pretty happy with the rear dropout brazing actually. I got really good penetration. I ran a larger tip on the torch and that helped quite a bit. I definitely ran it hotter than the previous joints, but it went MUCH faster, so I'm satisfied with the results. I'm not worried about the HT brazing since it's such an inherently strong configuration. I probably could have tacked it and it would have been more than strong enough.

I had a really cool setup for aligning and brazing the rear dropouts but the camera batteries were dead that day so I didn't get any photos. The Breezer dropouts I used were harder to use than I had thought. They look like they are cylindrical in cross section but they are actually slightly conical. I fitted them by clamping both legs to a board so that the ends were close together and filing them evenly. But I had to do a lot of dremel work to fit the conical section of the dropouts.

To align the rearfork, I first made a false axle supported between two wood blocks. I used a 3/8" rod for the false axle and carefully aligned it perpendicular to the maintube with the fixed nuts set at 135mm apart. I then made wood offset blocks to hold up the maintube at a fixed dimension (2.707") above the plane of the jig. I used a scrap of 2.5" AL tubing to center the ends of the rearfork on the maintube. To miter them, I'm going to use either a laser or just a pencil to scribe around the maintube onto the rearfork arms. I'll need to mount the maintube temporarily behind the rearfork connection to scribe the back. I still need to clamp everything in place. These pics are just a preliminary fit.

I should explain the piece of 5/8" tube running through the headtube. It's held in place with press-fit wood spacers that I turned on the metal-lathe to keep it centered. The cylinder on the end is turned to the same diameter as the width of the BB shell. I will also turn one that is 2" diameter the same as the maintube. By mounting this and then squaring it to the jig, I can ensure that the headtube is perpendicular to the rearfork within good tolerances. I can also use the 68mm one to ensure that the BB is square. I'll post more pics of the technique as I get to it.

Progress!

2007-11-05T05:02:00.001-08:00

I've made a lot of progress in the last couple days. I did nothing for over a week but I got a good day of work in on Sunday. I have more than just this post, but I need to take more pictures so I'll post them up soon.

In short, I laid out everything on the maintube, cut all the holes, and brazed in the seat mounting nuts.

Laying out the maintube

I printed out the cutting templates I created with my little DeltaCad macro. I first scribed a line on the maintube. Then I put on the BB template carefully aligned on the scribe. I then measured off an offset from a mark on the template and scribed a mark on the longitudinal scribe line to align my HT template with. Wash, rinse repeat.

I should note that I forgot to make a template at first for the end cutoff and the angled cut at the bottom of the BB, so I had to retrofit those later working from the existing marks.

Head Tube cutout marked with center punch

To mark the cut lines, I used an automatic center punch through the paper templates, and then cut the templates off. This proved to work VERY well. The marks are easy to see and follow, and give visible feedback as you file/grind the finished miters. As you approach the punch mark, you can see little divots growing on the filed edge. it proved to be easy to get a PERFECT fit for the headtube.

Bottom Bracket

I marked out the BB hole the same way as the head tube. Here you can really see the utility of a marking template. Because the BB is off center, the hole doesn't look like a slightly elongated circle, but rather a figure 8. I didn't think of adding in the lower angled cut portion of the cut to this template, so after this was marked, I made a new template that just had the angled line on it, cut it carefully to the line, put the template on, and slid it up the tube until it was tangent with the front marks of the BB cut. This worked very well. The finished cut, which I'll post later, looks a bit like a boar's mouth with tusks.

Seat mounting nut

For the seat mounting I am using a brazed in nut and slotted plate arrangement a la Volae. The nuts I'm using are weld nuts from McMaster Carr. They have 6mm threading and are 14mm long. The OD of the barrel is about 7.5mm. After I center punched the holes for the weld nuts, I drilled the holes out on the drill press first using a small bit, and then a 5/16" (I think) bit. I then used a countersink to chamfer the holes since the weld nuts have a slightly rounded transition. The nuts were a tight fit in the holes, which is a good thing.

To hold them in place while brazing I used a piece of 6mm stainless steel threaded rod run from left to right through both nuts. The rod was removed between brazes, but you get the idea. This worked well except for the 3rd braze where the rod got stuck in the nut. I suspect some flux got in the threads. I tore a few threads off the end of the rod, but was fortunately able to save the nut by drilling and tapping it. If I had to do it again, I'd run the rod in from below, and put a bolt in from above to keep the threads clean before fluxing. Brass doesn't stick to stainless so that should be safe (and is how I did it for the 4th nut)

To clean up the brazes I started with a flat file, but that wasn't real great. I tried using a dental burr which seemed to work well but made my hand numb after a while. I also realized that I had nicked the tube in a few spots, you can see these in the last pic. They aren't as bad as they look in the pic but they are bad enough I can't sand them out easily. I don't think they will be a structural concern but they annoy me. Ah well, it's my first frame, live and learn. I later switched to using a small but aggressive cutting half round file for cleanup. I like it much better.

Tube Miter Software

2007-10-31T08:01:00.000-07:00

Giles Puckett wrote a nice little windows app some years ago called tubemiter that will plot out a curve on a piece of paper that you then wrap around a tube to act as a cutting guide. This is a great idea, only his application is limited because A) it doesn't allow for tubes that meet with an offset (i.e. the center axis of the two cylinders don't intersect). And B) it only prints the end miter, it's up to you to figure out how to align it.

I'd like to extend his application by adding more reference lines, an offset parameter, and possibly even the ability to put multiple miters on a single printout to minimize compounding errors from measurement. If I could plot out both my headtube and BB intersections, and print it on an 11x17 piece of paper, that would be awesome.

Instead of using a standalone windows application, I decided that the best bang for the buck would come by writing a script for my favored CAD program, DeltaCad. By using a CAD program rather than a standalone app, I can dimension and draw in other references as needed. I can also plot multiple intersections and cut and paste them onto my final drawing. The only drawback to this approach is that the macro runner is a bit flaky when run out of wine under linux, such is life I suppose.

I should point out that modifying the script to work with elliptical tubing would be pretty trivial. If anyone is interested I'd be happy to make the changes.

You can download a demo copy of DeltaCad from the website, and a copy of my script here. To run it, go to the macro tab. Click "Edit macro list" and add the tubemiter file to the list. Then select it from the pulldown and select run macro.

Stuff I need to Order

2007-10-25T10:04:00.000-07:00

This is a list of stuff I need to order to actually continue to make any progress on the bike. Hard to make things when you don't have the materials...

From Nova:

Head Tube
BB shell
10x cable stops
breezer dropouts (with boss)
MTB fork blades (29er)
4 Pinch bolts
canti bosses (max offset)

From Atom:

Seat

From Online Metals:

20ga flat sheet
Square tube (for idler mount)
6" 5/8" x .065" tubing
2' 1.125" x .065" Aluminum 6061 -T6

From McMaster-Carr:

Weld nuts (90563A640)
silver brazing alloy (??) (76955A72)
silver flux (black, white?)
6mm SS bolt (for fixturing) (92000A450)
6mm SS socket head bolt (91292A141)
8mm SS socket head bolt (for idler axle) (92290A461)
8x10mm bushing for idler bearing holder (6679K13) (might need 10mm version)

To-Do List

2007-10-24T12:08:00.000-07:00

I find it helpful to write down all the things I need to accomplish from time to time just to wrap my head around what's coming and to sort out the places I need to understand better. This includes what needs done, as well as any points on how to do it that I've thought of.

Things I need to do in order to get the maintube, HT, and BB brazed up. (I'll do rear fork and finishing steps, seat mounting, sprint stays, etc. later)

Level jig on saw horses
Decide if I am brazing FD mount along with everything else or later separately, and what size tubing I'm using for it.

machine appropriate spacer blocks
figure out how to miter the thing.

Prepare jig

Draw out maintube, head tube and BB locations on jig (FD mount?)
mount spacer blocks
machine wooden square blocks for angle alignment brackets and mount
Drill and prepare for BB fixing bolt

Mark out maintube

Mark 90 deg longitudinal lines on maintube

Mark intersections for headtube, BB, and seat mounting penetrations
Print out tube miters for HT and BB penetrations, align with longitudinal lines, transfer to tube with centerpunch and marker.

Prepare HT

Use cutoff tool on lathe to cut partway through tube to mark accurate square cutoff for cutting to length later with hacksaw/file (post brazing)
drill breather holes
mark intersection with maintube for positioning purposes

Cut maintube

Cut out headtube penetration.

start with dremel
clean up to marked line with 1" drum in die grinder
Test fit in jig, wash rinse repeat

Cut out BB penetration

hacksaw lower bevel & rough out
finish with 10" half round file and 1" drum
Test fit

Cut and fit plate for lower bevel under BB
Cut and fit FD mount
Drill holes for seat mount

This is important to do before any brazing since I am doing it on the mill and any brazing material could throw it off depending on exactly how I mount it

Mount HT, BB, lower bevel plate in jig.
spot braze LH side of headtube, and Top and Bottom of BB (braze both LBP and BB )
Take frame out of jig and flip over
remount (if this is hard, something warped)
braze RH side of ht
take frame out of jig, mount in frame stand and finish braze all joints.
aligning and brazing seat mounts: (assuming working on LH side)

start by running a SS bolt all the way through from the RH side of the frame so that the nuts are tight but it only contacts the first couple threads on the LH nut
mount a piece of AL flat stock to the LH nut using a short bolt
sight along the maintube and ensure that the flat stock is parallel with HT, also measure with square.
adjust as needed
carefully remove flat stock without shifting nut
braze in nut
repeat for other side

Steering Geometry

2007-10-21T05:55:00.000-07:00

In spite of the fact that the modern bicycle has been around for considerably over a century and even the recumbent bicycle for over 80 years, understanding bicycle steering is a persistently difficult problem in dynamics.

Contrary to popular belief, gyroscopic forces play only a minimal role in determining 2 wheel vehicle stability. Check out this site for a whole bunch of interesting experiments with counter spinning wheels and interesting steering geometries.

Another bit of required reading is David Jones' classic treatise on bicycle stability in which he attempts to build unridable bikes.

For this subject and just about everything else related to bicycle technology, check out Bicycling Science.

Finally for a good, relatively concise writeup on the dynamics of 2 wheel vehicles , check out this wikipedia article.

Boiling down the above, there are really 3 variables that we can vary with our design.

Fork Rake
Head Tube Angle
Wheel Diameter

The combination of the above give us:

The difference between mechanical trail and trail seems subtle, and in fact it is, but Jim Papadopoulos makes the case in bicycling science that MT is a more relevant measurement of how the bike actually handles. It represents the lever arm through which the perpendicular component of the vertical support force acts. In other words it is the lever length that forces the wheel to turn in the direction of a turn when you lean the bike. It's also interesting to note that two bicycles which have the same T may have a very different MT due to differences in head tube angle.

Having said all that, increasing T and MT all other things being equal will cause the bike to be more stable. Stability is a bit of a loaded term since it is usually used in the above mentioned documentations to discuss the ridabilty of a bicycle hands-free. For my purposes however I'm considering a more subjective view. A "stable" bike is one that feels like it is "on rails" and wants to hold it's line. An unstable bike is one that is lively feeling and handles quickly. The best handling bikes are compromises between the two. It would be easy to make a bike so stable that it was practically impossible to knock over once at speed. Unfortunately it would also be so stable that swerving to avoid that car or pothole would be equally impossible.

For my particular design I'm starting with an existing fork. It's a kinesis 650C Aluminum Tri fork. It's light, good quality, and fits the 559 wheel size adequately with either long reach brakes or some creativity. I measured the rake on this fork to be 34.54mm, and it's axle to crown length is 340.36mm. I'm also decided on using 559 rims with 25mm tires for the purposes of this design. If I ever want to use wider tires (for touring for example) I'll need to make a new fork anyway since this one won't clear wide tires. At that point I'll simply optimize it's rake for the new wheel size.

Since I have 2 of my variables fixed already by deciding on a fork and a wheel size, I need only to decide on head tube angle. The first thing I did on my drawing was to draw in the fork rake by drawing a circle with radius 34.54 centered on the front axle. Then for the heck of it I drew in case where the headtube was simply perpendicular to the maintube. This is the maroon line. This gives me a headtube angle of about 71.3, T of 68.61 and MT of 65. These T and MT numbers are very high. The highest MT listed in a table of common values in Bicycling Science (Table 8.1, p274 of Third ed) is 58.5, and the highest T's are 76.2 and 69.8, but both are found on track bikes. This does however put it close to the Bacchetta Aero, which is obviously a successful design.

I am still uncomfortable with the very high MT and T numbers so I decided to see what I would get if I fixed the trail at 60mm. This is a good common number for a stable touring (or similar) bike. This is the blue line. I get a HTA of 72.8 and a MT of 57.32. These are still on the stable end of normal, but they are much more inline with what is out there in the upright world. This also puts my trail nicely between the 70's of the Aero and the 50mm of the Volae Team.

Drawing the Frame in CAD

2007-10-19T11:30:00.000-07:00

We now have all the info we need to draw up the frame in CAD. To recap we are going to use the following values: (SR = seat reference mark)

SR above ground = 609.6mm (24")
C of G behind SR = 39.7mm
BB center above SR = 228.6mm (9")
BB center in front of SR = 783mm
Heel Clearance = 75mm

FYI the CAD program I'm using is a nice shareware program called DeltaCAD. It's pretty easy to use and I've gotten used to it's quirks. There are more featured apps out there, but familiarity is worth more than features in this case. It's a windows app but runs well under wine on linux.

Step 1:
Draw a horizontal line that is 2000mm long. Then in the center draw a vertical line that is 1000mm tall. The horizontal line is the groundline and the vertical line is the center of gravity.

Step 2:
Draw a vertical line that is 609.6mm tall, 39.7mm in front of the C of G. This represents the SR. Then draw a second vertical line that is 609.60 + 228.6 = 838.20 mm tall, 783mm in front of the SR. This is the BB center.

Step 3:

Now we need to know the wheel dimensions. We are going to use conventional 26" mtb wheels, but with narrow, 25mm tires. To get the outer diameter of the finished wheel, you take the bead seat diameter of the wheel, 559mm for us. Add 13mm for the bead height, then divide by 2 to get the radius and add the tire dimension (25mm). So we get (559+13)/2 + 25 = 311mm.

Draw a horizontal line 311 mm above the ground line.

We now need to find the front axle location. To do this we will need the heel clearance dimension which is 75mm. I've defined this as the distance between the arc defined by a 175mm crank and the top of the tire. But in this case we really want to find the distance that is 175mm + heel clearance + wheel radius = 175 + 75+ 311 = 561mm away from the BB center. Draw a circle with this radius and mark on the axle line where it intersects. This is the front axle location.

Step 4:

Draw in the wheel and measure the distance from the c of g line. In this case it is 630.92mm. We will use this in the next step.

Step 5:

Now that we have the front axle distance from the c of g, we can find the location of the rear axle. But first we need to decide on the weight distribution. I said previously I want between 45 and 50% on the front wheel. So I'm arbitrarily deciding on 48%. Now we need to solve for the wheelbase. 630.92 = (100%-48%)*wheelbase. Wheelbase = 1213.31. Mark out the rear axle location 1213.31mm from the front axle and draw in the wheel.

Step 6:

We are going to braze in the BB for this bike off center so that the top edge of the BB shell is a the same level as the top of the maintube. This give us better front derailleur clearance. So I took a look at Nova cycles and found this BB shell. It has an OD of 31.8mm so we draw a circle of that diameter centered on the BB center.

We then need to ensure that the maintube clears the seat. Conveniently we used the low point of the seat for the SR, so we just need to account for the thickness of the seat and a little extra. The seat I am considering is wood, and is ~3/8" thick. So I gave 15mm of clearance. I draw a circle with r=15 centered on the SR.

Then draw a line that is tangent to both circles and ends at the rear tire (we'll shorten it later). This is the top edge of the maintube.

Step 7:

Finally draw a parallel line that is 50.8mm below the top line of the maintube, then draw a longer parallel line that is halfway between them that extends to the rear axle. Mark the offset from the axle.

So far so good! The wheelbase looks good as does the rear axle offset. Next time I'll talk about steering geometry.

BB to Seat Distance Measurement

2007-10-19T09:50:00.000-07:00

This is pretty simple. I again took my mockup seat and this time just placed it facing the wall. I put a mark on the wall with masking tape that is the right height above the seat base to represent the pedal when the crank arm is horizontal. In my case, as discussed previously, this would be 9" above the seat reference.

I then put on my cycling shoes, sat in the seat, put my heels on the mark and pushed myself backwards. Then fine tuned it a hair to get the leg bend that seemed right when my cleats were on the mark. For me the distance from the wall to my seat reference was 96.3cm. I use Time ATAC pedals which have a stack height of about 1cm (not including the cleat here). And I'll probably be using 170mm cranks. So my actual BB center is 96.3 - 17 - 1 = 78.3cm in front of my seat reference.

Interestingly when I get my new, real, seat I can use this same method to figure out where the seat reference is. I'll prop the seat up at 28 deg from horizontal and push away from the wall the right distance, measure 96.3cm, draw my mark, and there we go.

Weight Distribution

2007-10-19T09:23:00.001-07:00

As I discussed in the last post, I am trying to optimize weight distribution for this bike. To that end I need to know where my center of gravity is when in riding position, or at least where a vertical line that passes through my C of G is. I'm not going to worry about the weight distribution of the bike itself since that would add a huge amount of complexity to the process (without actually having the bike yet) and really it would only change the result by a pound or 2 in either direction which isn't enough to matter.

To do this I basically took a mockup bent seat I built previously that is set at 28deg from horizontal when sitting on a flat surface. I put it on a pair of 2x4's that were supported at the ends by a bathroom scale on one end and some scrap on the other to make it level. I put it roughly in the middle but just marked it so it's position is known. I then took 3 sets of readings 1 each with me on the contraption and with me off of it. I then swapped the scale to the other end and did another set of readings. Here is a link to my raw data.

As you can see I had some help with this. Also the living room is not really as much of a disaster as it looks in the pics. I swear!

Looking at the data. We take the average of the loaded measurements and subtract off the average of the unloaded measurements for both front and back respectively. This gives us 102.33 lbs on the front and 81.66 lbs on the back. So 55.62% of the weight was on the front. The 2x4's were 206cm between the measurement points. So to calculate the c of g, we take (100%-55.62%) * 206cm = 91.42cm which is the distance the c of g is from the front of the 2x4. We also know that the seat reference mark was 87.45cm from the front. So my C of G is 91.42-87.45 = 3.97cm behind the seat reference mark. Good to know!

Factors in Frame Design

2007-10-19T07:09:00.000-07:00

The type of frame I am building is pretty simple, but there are still a number of factors to consider. Many of these techniques would be applicable to building any recumbent. Some of the factors will be inputs into the design and some will be outputs. Because I am building my first frame, I am considering the existing work that is out there, particularly from Volae and Bacchetta, with the expectation that if I am near them in terms of geometry, I'll have something that works. Having said that I am designing this frame from scratch and thinking about all the trade offs.

Lets look at the factors in detail:

Weight Distribution: I'd like to design this bike so that between 45 and 50% of the total weight is carried on the front wheel. Equal weight distribution is rumored to be nearly optimal in terms of handling. I don't know this from experience but it sure sounds good on paper so I'll go with it as a design criteria. In order to figure this out we need to find our center of gravity, which is dependent on several other things.

Seat Angle: I need to consider seat angle in order to calculate my center of gravity. I've fixed this for the purposes of this process at 28 deg from horizontal. I built a mockup seat that I could change the angle of and found that to be a comfortable angle for me. Using the same seat that will ultimately be used on the bike would be better, but I don't have it yet.

Seat Reference: The next thing to consider is where we are measuring the seat from. I decided to use the lowest point of the seat as my reference. I will be able to transfer this to the final seat I use later.

Bottom Bracket Height: This is calculated relative to seat height and it's something I don't have a good way to calculate. I could let it be an output of the process and optimize some other variables... but I decided it's easier to just pick a number and design around it. In this case I just copied the bacchetta aero dimension of ~9"

Wheelbase: This will be an output of the process in my case. I'm not going in with any preconceived notions of what it should be other than to say it should be in the same ballpark as the common highracers on the market. For reference the Aero is in the range of 1240mm and the Volae Team is around 1195mm.

Seat Height: I wish I could say that I arrived at this through some clever method, but really I just looked at what is out there and picked 24". That's in between the Bacchetta Aero which is around 23" and the Volae Expedition which is around 25".

Distance from BB to Seat Reference: AKA leg length. This was determined experimentally using a method I'll describe in a later post. It's a very important measure if I want to optimize weight distribution since I'm going with a sliding seat type of build. Using an adjustable boom would make this less important but would be more complex in other areas.

Steering Geometry: This really deserves a whole post of it's own so I'll pretty much say that what I'm going for is something between the Aero and the Volae bikes in terms of geometry. The trail is the most meaningful number when describing different geometries (all other things being similar). For reference the Aero has a trail of 71.5mm and the Volae Team has a trail of 50mm. Taken in a vacuum this would suggest that the Aero is more stable almost to the point of being dead while the Volae is a bit quicker steering. Overall I'd favor stability but I'll probably bring the trail in a little in my design. I'm going to let this mostly be an output however as long as it's within "normal" ranges.

Heel Clearance: I've defined this as the distance between the arc defined by the pedal spindle on a 175mm crank and the top of the front tire. This is not a standard definition AFAIK but it's easy to measure from pictures and works well for designing in CAD. For reference the Aero has a HC of 60mm and the Team of 86mm. I split the difference and rounded up a little and decided to go with 75mm. Again, this is something that only experience will tell me what works well, and I don't have experience so I'll just guess but keep it within established ranges.

Frame jig construction

2007-10-19T06:28:00.000-07:00

This is pretty simple. It's a piece of 2cm MDF with stiffeners screwed and glued to the underside.

The whole thing is about 6.5' long x 16" wide. It's within about .005" of flat (according to my level) Good enough. I used one of the factory edges of the MDF as a routing guide with a pattern bit to straighten the long stiffener pieces. I cut out the cross pieces on the mill, but the same router technique could have been used there.

Brazing Experiments

2007-10-18T16:09:00.000-07:00

Last weekend I finally got the oxygen bottle to go with the torch I picked up on ebay some weeks ago. I am using propane driven with an acetlyene regulator after some reading on the framebuilders list that this is a safe and reasonable option. The whole kit cost me only about $180 including shipping but not including the propane since I already had the bottle on my grill.

I had also ordered some 1" x .035" wall tubing from Aircraft Spruce to practice on. Overall I'm very happy with the results. Even my first braze had reasonable penetration and draw through the joint. I brazed up my second and third joints in a sort of drunken H and tried to break them and was unable to. I twisted and mashed the tubing all to hell and even bent the heavy wall 3/4" steel pipe I was using to try to bend it with, but the joints didn't budge.

I also cut apart my 1st and 4th attempts to look at the penetration and overall fillet quality. I'm not saying I'm anything like a pro yet, but what I did on my first few attempts would have easily held a bike together and even looked reasonably good with a bit of cleanup. That's good enough for me for this project.

Recumbent project

2007-10-18T14:47:00.000-07:00

For several years now I've been wanting to build a recumbent bike. Perhaps it's my inner geek showing through, but they just strike me as an inherently better platform for long distance, on-road touring and endurance riding. Recently I've been having upper back problems which have further encouraged the idea.

The style I'm interested in is a high-racer in the Volae or Bacchetta model. To my inexperienced eyes this type of bike has several advantages overall and several specific to the home builder.

Highracers use common sizes of wheels and thus gearing which makes finding parts easier, particularly out in the middle of nowhere. I can pick up MTB wheels at nearly any bike shop in the world. Other sizes may be more hit or miss. They have an aerodynamic position which is superior to most unfaired bikes of any stripe with the exception of low racers. However they put your head height near that of most cars which is better for riding in heavy traffic. They are also more "normal" looking somehow. Due to the higher rider height, they play nicer with riders on conventional diamond frame bikes than most recumbents.

Specific to the homebuilder, the main frame is nothing more than a straight piece of .035" wall 2" diameter cromoly tubing. The rear fork is comprised of common MTB fork blades. The rest of the frame is all common frame builder parts. There is no tube bending required or other complex techniques. The jigging for the frame can be quite simple. The fork presents a slight problem in that you are restricted to either tight clearance 650C tri forks which limit tire choice, or MTB forks which are way overkill on clearances. There are other choices, but the two I listed are the most common and cheapest.

Material is something I pondered for a long time. Carbon fiber is a reasonable option and a number of homebuilders have used it to make beautiful bikes. Jim Scozzafava has made some bikes that are the equal of many production bikes costing many thousands of dollars. I also tossed around the idea of an Aluminum carbon hybrid with AL tubes and wrapped carbon lugs. But in the end I settled on fillet brazed steel. I thought about using my mig welder, but I wasn't able to get good enough welds on the thin tubing to satisfy my inner perfectionist.

Steel has a few advantages. First it's relatively cheap and commonly available. It's also reasonably forgiving of mistakes. The biggest factor to me is that I am reasonably sure I can make a durable and long lasting bike from steel. I am not as sure with any of the other materials. There are also a lot of frame parts readily available for steel frames. The same cannot be said for carbon. This isn't a huge issue, but each little thing I need to make myself adds time and effort.

Seats, mounting, stay construction, idlers, steering mast and handlebars, etc are all things I've thought about a lot, but those will have to wait for later posts.

First Post

2007-10-17T18:43:00.001-07:00

My goal for this blog is to be a repository for all the bikish stuff I do. Building, riding, whatever. Not much of a mission statement I guess, but it's all I got.