going shorter crank length - any regrets

[benb]

Originally Posted by Mark McM

One note here is that if cranks scaled in proportion as riders got bigger and smaller. then joint range of motion would be same for bigger and smaller cyclists. But cranks often don't scale in proportion*. For example, A 150cm tall cyclist on 150mm cranks would have the same joint angles as a 190cm tall cyclist on 190mm cranks, if the two cyclists had the exact same ratios of proportions. But most models of cranks don't come in that range of lengths, so smaller cyclists tend to ride with proportionally long cranks and with the accompanying larger range of joint angles, while taller cyclists tend to ride with proportionally short cranks andwith the accompanying smaller range of joint angles.. Perhaps the recent move to shorter cranks is simply a "correction" for people at the lower end of the height/leg length scale.


*This is part of the bike industry's mantra about bike fit - "Fit the bike to the cyclist, not the cyclist to the bike - unless it's not convenient or it cuts into profits, then fit the cyclist to the bike."

This is ignoring whether shorter and taller riders even have the same proportions as well, which is of course convenient for keeping manufacturing costs down.

I think it's commonly accepted taller riders have longer legs proportionally but I've never heard anything about whether femur to tib/fib ratio changes as height increases.

Foot size also increases in a non-linear fashion as well.

For yet more anecdotal evidence:

185cm tall
88cm inseam IIRC
Have had recommended saddle heights from different fitters all the way from 77-81cm although the 81cm was definitely an outlier. Most between 77-78.5cm.

Always happiest on 175, but I had one bike built up with 172.5 for a year and had a fixie with something really small like 160 or 165. All were fine.

Shorter cranks also effect your setback as far as I can tell. In my case I really feel like this has an important effect on my fit as I tend to be reach limited on stock frames and if a shorter crank requires me to push the saddle back on the rails that can impact other parts of the bike fit. Pushing the saddle back also closes the hip angle which brings back some of the same problems at the top of the pedal stroke as excessively long cranks AFAICT.

I've never tried a 180, even if it was just taking someone else's bike for a little spin I would jump at the chance.