Originally Posted by
Paramount1973
With all due respect, your reply does not make sense to me. The study ran riders of various heights though a progressions of crank sizes from quite short to long and found a very small difference in pedaling efficiency. There may be other reasons to select a specific crank length, such as alleviating knee pain, but this study indicates pedaling efficiency is not one of them. Moreover, it states that one can pick a favorite crank length without concern for losing too much pedaling efficiency.
If you look at the study, you will see large gaps in the crank arm sizes, enough for the ideal length for a particular rider to be skipped over. 'Hasty Generalization' is a logical fallacy (the use of any logical fallacy in an argument indicates a good bet that the conclusion is erroneous) wherein the sample size is too limited to be meaningful.
The difference between the right crank and the wrong one will not be a large value- it may well be only about 3-5%. But in bicycles, that can be a pretty large figure, given how little differences there are in the performance of many components. It can certainly make a difference in a race. More:
http://http://bikesmithdesign.com/Short_Cranks/rom.html
https://www.powercranks.com/