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Old 09-05-07, 11:41 AM   #1
int19
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Ashtabula crank, fixed gear

Hello all,

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:
http://cgi.ebay.com.au/Old-School-BMX-Chainwheel-Spider-Disc-Alloy-Red-1980's_W0QQitemZ330161715662QQcmdZViewItem

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?

Thanks,
Richard
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Old 09-05-07, 11:45 AM   #2
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Not sure if your ring has the material to do so, but what about turning it 180 degrees (or enough to clear the old hole) and drilling the proper size hole?
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Old 09-05-07, 12:24 PM   #3
int19
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Hmm... that's an idea... thanks!
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Originally Posted by I_bRAD View Post
Not sure if your ring has the material to do so, but what about turning it 180 degrees (or enough to clear the old hole) and drilling the proper size hole?
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Old 09-06-07, 09:56 PM   #4
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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.
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Old 09-24-09, 10:41 AM   #5
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iv got this problem too, on my se 08 that **** is getting more and more ****ed up, i wedge cardboard pieces into it with a edge of a knife, worked for about 10 minutes
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Old 09-24-09, 12:36 PM   #6
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If the spider is aluminum, you may have problems with wedges. Aluminum is simply too soft, unless you can devise a wedge that supports most, if not all of the hole.
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Old 09-24-09, 01:17 PM   #7
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Can you get a bolt with a conical head and counterbore the hole in the chainring to match?
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