BB to Seat Distance Measurement

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.