I have a Sugino 75 170mm on my fixed, which I feel is a great compromise for road routes, and recently put a 172.5 on my SS for that added leverage on the slightly longer, hilly routes I cover with it. I recently read an article promoting the virtues of very short arms, like below 150, citing a supposed mechanical advantage with all kinds of anecdotal evidence utilized as supportive data. Seemed at least compelling.
To be honest, I rode with 165's for years but always felt they were too short and feel better with longer arms, but being the curious (and actually open minded…..sometimes…) sort that I am, I wanted to hear some of your perspectives on this issue. BTW, I'm 6 ft. with a fairly long 34 in. inseam, if that matters.