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Old 01-31-23, 04:36 AM
  #42  
PeteHski
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Originally Posted by beng1

A clydesdale rider like myself, who is well over six-feet tall and weighs over 200 pounds, can use longer pedal cranks if anyone can. I have tested a lot of bikes in a short period of time over an old level TT course for average speed and the fastest times always come from the bikes with the longest pedal cranks. With the long cranks a rider pedaling at their top cadence can either hold the same gear up a grade easier than with shorter cranks, or on the level can possible hold a gear higher than with shorter cranks for a longer period of time. Big, long heavy legs are just harder to spin higher cadence with, but the longer cranks will let a big and tall rider have more torque and the same power at a low cadence, as a small, lighter rider will at a higher crank rpm with short cranks. It is no different than getting power from an internal combustion engine where rpm x torque = power. If you can not get the rpm, a longer stroke can make the same power at a lower rpm.
The thing to remember with crank length vs cadence is that for longer cranks it is harder to maintain cadence as your foot speed will be higher for a given cadence (pedalling in a larger circumference). So the increased torque is cancelled out by the effective reduction in cadence. It's worth noting that Brad Wiggins ( who is 190 cm tall) set his hour record on 170 mm cranks after switching from 177.5 mm cranks. The 2016 men's Olympic GB track team used 165 mm cranks.

Crank length really comes down to personal preference based on your stroke length, but there is no inherent advantage to running longer cranks - especially on a multi-geared bike where you can manipulate torque vs cadence at will. However, there are several potential advantages to running shorter cranks e.g. allowing a more aerodynamic position and less demanding on your range of joint articulation. I've discussed this with two very experienced fitters and they both advocate relatively short cranks, even for tall riders.
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