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Old 01-25-2010, 03:38 AM
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Maxvision Maxvision is offline
Motorized Bicycle Elite Member
Join Date: Jun 2009
Location: San Diego, CA
Posts: 551
Default Re: Rag joint on 72-spoke wheels

I had the same problem with a 68 spoke rims I used once. Was a MAJOR effort to overcome the problem but it's do-able.

The bolt holes on your sproket have to be redrilled further out from center. I don't know if a 72 spoke wheel will allow you to use the original bolt holes as guides and just move the holes out further. I wasn't able to on my 68 spoke wheel as all the bolts would go in but the last hole still had a spoke in the way.

So here's what I did:

I used Photoshop to draw my hub and spokes to scale and figured the bolt holes from that. They ended up having to be drilled further away from center. I had to re-space all the holes and even at that they were all spaced evenly except for 2 that needed a little wider distance between them then all the rest.

Had to make 2 new half round clamp plates for the other side of the sprocket too (side with the bolt nuts). I bought a 1/4" aluminum plate, turned it down on a metal lathe, drilled the holes then cut it in half to make 2 half round plates.

Also had to buy some thicker reinforced rubber (3/4 in.) to use as the spacers on the spokes so the sprocket would fit far enough outside the wheel without the chain rubbing the tire. I was lucky enough to find a sheet of it at an industrial salvage yard. I drilled the bolt holes on a drill press and had to cut the spacers out with a band saw. That reinforced rubber is TOUGH stuff, don't even bother trying to cutting them out with a knife.

My brake bar wouldn't fit inside the axel hole of the sprocket either. It might have been possible to just grind down the edges of the brake bar on a grinder but I had the metal lathe so I turned the rear sprocket to make the axel hole larger. Also had to bend the brake bar just a tad so the heads of the sprocket bolts wouldn't hit it.

So, unless you have or know a friend who has Cad software, a metal lathe, bandsaw and drill press you might want to dump your 72 spoke wheels for some 36 spoke ones.

Last edited by Maxvision; 01-25-2010 at 04:14 AM.
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