Originally Posted by
pierce
this crank apparently has no published specs, at least I can't find anything from the manufacturer, and there was nothing in or on the package.
http://www.origin-8.com/?page_id=91&...+ARMS+%26+SETS
no hub changes, either, same wheel, cassette etc. 135mm nut-to-nut, with a 8 speed cassette.
soooo. I didnt measure the original chainline but
Shimano says my old FC-M191 crankset is intended for a 47.5mm chainline using a 122.5mm wide bottom bracket.
new crank installed on old BB measures 54mm wide, so I want to take 54-47.5 == 6.5mm off each side, or 13mm total off my BB axle length, right? so instead of the 122.5, I want a 109.5, basically 110mm should be close enough, right?
Without seeing it, your math seems OK. Be sure to check chainstay clearances for both crank arms, and at the chainrings before buying.
Also check the right land left spindle lengths. Most spindles aren't symmetrical, so you want to confirm that you're taking 7mm or so off the right side. The left has more latitude, so check the crank/chainstay clearance there and shop accordingly