I'm converting my old steel Specialized MTB to singlespeed. I have a Surly singlespeed MTB rear wheel. I have Primo BMX cranks. I figured I would measure the chainline error and then buy a BB that would align them.
I figure I need a 148mm square taper BB to make the chainline perfect. I don't think such a thing exists. The longest Shimano BB I found was 127mm That would leave me over 1 cm offset between the chainring and freewheel.
Looks like I bought a crank and wheel which are not compatible in terms of chainline. Ooops.
1. Mount the chainwheel on the outside of the crank arm spider. Anyone do this? It fits better on the inside. There is a machined ledge there for it. The outside of the spider has countersunk holes that help allign the bolts. This option alone doesn't solve the problem, but it gets me closer.
2. Use a rear wheel with a narrower hub. This probably means a custom built wheel. Save the Surly wheel for another project.
3. Buy a set of MTB cranks. Save the Primo's for another project.
4. Get the longest BB I can find and don't worry about the allignment error.
What whould you do?