What no one isn't taking into consideration is factors like the bike frame and saddle height, it's all relative. Of course, I'll agree too that: longer leverage = easier climb. But that's just the physics book theory.
When I had 172.5 cranks, my knees would go a bit too high for my comfort (my inseam is 30 inch by the way). Now that I switched to 170s, I feel spinning with far more ease on the climbs, giving more torque to the pedals, but again that's just me, with my particular frame size and saddle height. To anybody else, there are a lot of variables. The best is to experiment with your own particular, current frame and saddle height and different crank lengths.
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