Bit if a bump…at the recommendation of my fitter I’ve been using 165’s on the TT bike for a while with really amazing results. This week I moved off the 172.5’s to 165’s on a new road bike due to a hip impingement exposed by the new bikes geometry (I think). I don’t know how to explain it clearly but, coming over the top I was using muscles or rather muscles were firing and resisting the natural pedal stroke. Negative watts is a way to look at it. 7.5mm less length (and raising the saddle by close to the same amount) is enough to relieve the hip and am able to come over the top waay easier.
I hope to see the same improvements like I did with the TT bike which are a bit more 5 minute+ power and better economy (lower HR for the same effort). Sprinting doesn’t seem to be negatively affected. Maybe a little slower getting peak torque but, no way to prove and certainly not enough to say positive or negative either way.
Anyways, the point is, some can really benefit from shorter cranks while others not so much. Those who can’t raise the saddle much and hip impinged I seriously recommend seeing a fitter.