the bottom bracket that you have right now is sized for a double chainring and it will most likely give you a crap chainline. This is bad. Get a new bottom bracket that corresponds with the crank that you are buying. The IRO drivetrain kit includes a botom bracket, cranks, chainring, chainring bolts, chain, cog, lockring, etc for 135. after that all that you need are wheels, a saddle that fits you, and a front brake and you are golden. should come to around 335 for low end stuff, up to 5 or 6 hundred for upper/mid range stuff.