Lastly, shorter cranks improve cadence/enable higher sustained cadence as the reduction in leg movement/reduced angles of leg movement inadvertently causes less oxygen uptake to the blood for the same RPM of cadence compared to standard/longer cranks (170mm) therefore when riding the body attempts to compensate for this decrease in oxygen uptake from the shorter cranks by increasing cadence (a higher speed of leg movement with a smaller pedal-turning circle instead of an otherwise lower cadence with a larger pedal-turning circle - with 170mm cranks) in order to get the same amount of oxygen circulating as before, on longer cranks. For this reason shorter cranks are also quite popular for those cyclists training for competitive events in order to improve the sustained cadence they are capable of (but obviously they switch back to longer cranks when the time comes for actually competing in the event they have been training for, in order to not be down on torque versus their rivals). Shorter cranks are basically a win-win for road cyclists especially non-competitive ones. For MTB on the other hand, even non-competitive MTB, it's not so clear cut as every bit of torque can be quite important, for traction as well as acceleration. Thanks for reading and sorry for the multiple posts, needed to raise my post count. Good luck once again and season's greetings!