I have a Bianchi fixed gear conversion. I had a worhtless crank on that i bought for $25 because i was so short on cash. I just got a stronglight crankset a few weeks ago. I got the crank on but I can't seem to get the chainring to fly stright thus my chain falls off after about a block of riding. If i spin my crankset without a chainring on it, it spins straight. Once I put the chainring on, it doesn't spin straight. What pattern am I supposed to tighted the bolts on my chainring? I think that's the problem, if it isn't does anyone else know what I'm supposed to do?