Originally Posted by
fietsbob
High tempo , spinner, might favor shorter cranks, slow tempo, often standing, may advantage leverage of longer ones,..
Maybe, but I found that riding my old MTB that came with 175mm cranks to be harder on my knees when climbing out of the saddle and have less of an issue with 170mm cranks. A key biomechanical factor is the angle of the knee bend when you start the power stroke and less is more. Though it may be that this factor was actually playing out a lot while I was in the saddle and just noticed it more out of the saddle.
Otto