I am looking into buying the parts to convert my bike to fixed gear. My bicycle has 126mm spacing in the rear dropouts, and i believe requires a 68mm shell for the BB. I would like to purchase the bulletproof cranks. In order to get a straight chain line what spindle length should i get the BB in? would 107mm be ok? also, will the bulletproof cranks fit any taperd square bb, (for instance the one made by IRO) without any type of conversions etc? And for the final question- I live in san francisco, ride long distances and of course there are lots of hills, whats is good gearing for an area like this?
1. Chainline depends on the hub, BB spindle, and crank. You need at least two nailed down in order to determine what you need for the third. And it may take some adjustment/trial and error.
2. Bulletproof cranks AFAIK take the standard shimano taper, which is more than likely what the IRO BB is. Though you can probably find a shimano UN53 or UN73 BB for the same price, and in a variety of spindle lengths. Campy taper is the only other type that I know of, and that's restricted to the more exotic manufacturers like Campy (duh) and Miche.
3. Gear ratios are all over the place. You'll probably hear that a 44/16 or thereabouts is pretty good. Try it, and if you don't like it see if you can trade your cog or chainring with somebody.
Originally Posted by Dr Irwin Goldstein
Men should never ride bicycles. Riding should be banned and outlawed. It is
the most irrational form of exercise I could ever bring to discussion.