ink1373

so i'm about to move most of my setup over to a new frame, and i need to find out what BB spindle length i should go for. i've been trying to decipher sheldon brown's chainline pages, and i'm still afluster.

he says that IRO hubs (which is what i'll be using) have a 36.0 "chainline center to shoulder". the frame i'll be using has 120 spacing. given this information, can anyone help me figure out which BB length is most appropriate? i get the feeling that i'm missing another number, but hey, you guys are helpful.

-n

arcellus

might not be the help you're looking for, but you could always root thru the old parts bin at your LBS and try a few.. they should buy back the ones you don't need. and then if you really want a brand new one you can measure it and a get a shiny one in the correct length.

RobbieIG

You are only half the way through. You also need to know how your crankset will work with what BB. Also, you take the hub chainlin center to shoulder, add your cog offset to it, and that's your chain line. The cog offsets are listed above the hub offsets on Sheldon's site. Match your chainline of the hub + cog to your BB + Crankset, and adjust BB as needed. You can get a few mm one way or the other by changing the cog you're using.