Originally Posted by
Polaris OBark
After reading this thread, I ordered a 165mm crankset. It will be interesting to compare it to my 172.5mm one that is otherwise identical.
One thing has me a bit worried: Presumably I will need to raise the seat-post by 7.5 mm. The bike was custom-build around my sizing and presumably with the 172.5mm crankset in mind. I wonder if the bike will handle any differently. Presumably the saddle to bar drop will be the most significant change.
This experiment is primarily motivated by pedal strikes off-road with my 650b wheels (which also presumably alter the original intended geometry of the framebuilder).
That's the intuitive view, but it depends how you currently set up your saddle height. In the article I linked to above, the fitter actually suggests starting with the same saddle height as you previously had with longer cranks. This reduces both leg extension at the bottom and hip closure / knee bend at the top by equal amounts i.e. the centre of rotation remains the same, with reduced extension and compression. Depending on your functional range of flexibility, either one or both of these reductions could be beneficial. Once you get a feel for the change you can then tweak the saddle height to optimise. But remember that the main benefits of a shorter crank are the reduced extension and compression angles throughout the pedal stroke. It is of particular benefit to anyone with limited flexibility in one or more joints i.e. most people!