I ride 180 mm cranks. On just about every bike I own. The only exceptions are my track bike (175 mm) and my single-speed/fixed-gear road bike (175 mm). Even our two tandems have 180 mm cranks in front and lately I'm getting pretty self conscious about this fact.
First some history.
Back in the day (read: the early 80s when Martin starting riding bicycles) everyone had 170s. It did not matter if you were 5' 6" or 6' 5", it's pretty much all there was. And no one cared about crank length, it was just a commodity that you needed to propel your bike forward.
Then someone I worked with suggested I try something longer. He thought longer cranks were cool and since I was 6' 2" I guess he felt a kinship of sorts and was compelled to impart this nugget of wisdom on the sponge-like disciple that was Martin. So when I purchased my first 'real' bike I got it with 172.5 mm cranks.
I know, I know, HUGE difference. In my head.
Time passes and I upgrade my components and the next time I got cranks I opted for 175 mm. Hey, it just seemed logical. By this time I was reading about pro riders and how some used longer cranks on their TT bikes and I was kinda tall after all so why not? I also worked in a bike shop so the parts did not cost so much given my employee discount.
Then I got my first custom bike. And what goes better with a new frame than all new components? Nothing, that was rhetorical. Say hello to 177.5 mm.
At this point the jump to 180 mm was almost incidental. I mean if a little longer is good then outrageously long must be better, right? Totally. At the time long stems were cool too. There were loads of juniors riding around with their arms totally straight because if they were bent they would not have been able to reach their handlebars. Peer pressure – or the mere appearance of it – is not to be underestimated.
Now I was far from being a junior... I started riding and racing when I was about 20 years old and by the time I fully submersed myself in bike culture complete with subscriptions to VeloNews (back when it was newsprint) and Cycle Sport magazine I was pretty advanced from my teens. But that mystique is strong. If you think something is cool or if you tell yourself it's cool long enough then by god it's cool and damn anyone show claims otherwise.
Plus I swore up and down that longer cranks were advantageous. Looking back now I vividly recall a study performed by Leonard "longer is better" Zinn where he had riders of various height ride up a hill at a constant heart rate with different length cranks. The riders did not know what length they were riding each time up the hill and they were asked to subjectively rate their effort. The results showed conclusively that each rider benefitted from longer cranks as the speed went up the longer you went while keeping the heart rate constant. There was even a tiny triathlete who was close to 5' tall and even she liked the 180s the best.
Hook, line and sinker.
Now I think I am relatively flexible – at least compared to the average Joe – and so the old adage of, "Go longer to increase your leverage until it affects your spin." was sort of my guide. And I never thought that my spin was being affected.
I had (of course) conveniently blocked out some experiences... like this one time a friend and I were riding up Hurricane Ridge. Climbing was no problem. Coming back down you have to pedal if you want to fly as the slope is just not that steep. What happened? Martin got dropped because he could not spin fast enough. And I was a reasonable descender! At the time I chalked it up to my saddle being too high and that might have been part of it but the other part might have been my crank length. You think?
Fast forward to the present. I'm having all kinds of issues with my back because I herniated a disk (or two) skiing when my core was ultra weak a few years ago. Unfortunately cycling is just about the worst thing for it. Straight spine = happy back, bent spine (especially for extended periods of time) = very, very unhappy back.
The problem with long crank arms is that when you round the top of the pedal stroke your hips get kicked up. As long as you are flexible and your core is strong it's manageable but as soon as you falter in either area like any time you don't religiously work on either or even just at the end of a long/hard race when your core is fatigued it causes more discomfort.
So what's my problem? Why not just stick 175 mm cranks on al my bikes and call it good?
Because I have so many! Upgrading them all to 180 was a huge financial investment and going back is quite daunting. Of course I could just buy arms for the bike I am riding right now and see how it goes...
I also honestly do not understand how a 15 mm range of sizes (165-180) an adequately meet the needs of people that vary in height from under 5' to well over 6'. If someone who is over a foot shorter than me AND has proportionally shorter legs than I do can comfortable ride 170s, why can't I ride 180s?
I guess the answer is just that we are not all the same in terms of what we can tolerate.
And I guess I have a mental block about switching. When some of your best rides and races and cycling experience were with one thing, it's hard to give that thing up.