I had some 165s and 170s and was fine ... but I had 175s on one bike and while I could barely feel any difference after the first minute ..... overall I Felt (no reason, no measurement) better with the 175s. So Now I have 175s on five of my six road bikes and I love it.

I cannot tell you if I spin faster or generate more torque or anything .... but I know some portion of my brain says "yes" more loudly on the longer cranks. I forget my cycling inseam, but I am a little over six feet and have ridiculously long legs for my height. I realize none of this really helps, sorry ...

But it is a lot more than height. leg strength, hip flexibility, lung and cardio capacity, slow to fast-twitch muscle proportions. ... all kinds of physiological uniquenesses determine what fits each of us best.

I say, get a set of 180s and see.Shop Ebay for used or take-offs or whatever, maybe .... if nothing else you can throw them back on EBay for a minimal hit and have important data.