Rag joint on 72-spoke wheels

jl_sparks said:

I'm having a very difficult time installing the rag joint on my 72-spoke wheel with a coaster brake. The brake arm is off and therefore out of the way entirely. I just can't get all 9 bolt holes to line up with a gap between the spokes at the same time. Anyone else had this problem? Maybe seeing a few pictures of a 72-spoke wheel with the rag joint installed (from the opposite side of the wheel from the sprocket) would help. This is my first build, by the way.

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I'm not sure it's possible but you can purchase a sprocket and adapter from Manic Mechanic as long as the hub is not conical or tapered....and what's so cool about that product is it drives the hub...not the spokes and also only uses three bolts to fit the sprocket on the adapter and more'n enough room for the brake arm.....the site is here on the forum to the left.....

Good luck,
Salty

jl_sparks said:

I'm going to try everything I can to make this work with the rag joint. I actually like the look of it, I already have it so no more money needs to be spent, and I'm not even sure those 3 hub adapter bolt holes would line up and fit between my spokes either.

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Rock and a hard place huh ?.....if you do figure it out and it works post some snaps for us....I'd love to learn how ......

Salty

i dont even like the rag joint on a 40 sprock.....good luck ....jim can save you alot of headache.

As far as Jims sprocket adapter goes....I don't think it's possible to get the clamshell inside the spokes without removing a few. "I Think" that he can make a sprocket that bolts directly to the flange. Contact him...

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.