I'm building a fixed gear on a bike with a one piece crank, and I have an aluminum chainring on a bmx spider like this one:
However, the hole for the pin on the spider is larger than the pin on the crank causing the pin to move back and forth in the hole when pedaling backwards and forwards. Is there some simple fix for this or do I need to upgrade the bottom bracket to support a standard crankset? If so, can you help me pick the offset that will preserve the straight chainline I have now?
I had this problem on a Varsity that I fixed. I cut out a small piece of metal and wedged it in the space between the problem pieces. It worked well. I also was considering some way to maybe swage, or mushroom , the end of the little bar to fit exactly in the hole, but I never got around to it.