Originally Posted by
late
Welcome to the club. With those long legs I suspect 175 may be your best bet.
I don't know what you have, but you could keep an eye on ebay for some used cranks in a size you want to try. Nashbar often has great prices on leftover cranks.
I'm 5'9" with a 35" inseam and I find 175mm cranks much more comfortable than anything shorter. I would like to try longer cranks, but they are hard to find.