I'm in the process of ordering new cranks, chain, BB, headset and front break for frame that was just painted. Paint looks HOT out in the sun. The bike's last previous life included life included fixed gear with 170mm cranks and 27" wheels that I'm keeping for at least a few months. I don't recall ever hitting the ground with these cranks, but I also never really rode it all that hard.
Is there a calculation or specific frame dimensions for deciding correct crank length?