Cottered Chain Wheel into 1 Piece BB?

Nov 6, 2019
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I very much want to use this chain wheel. I dont think they came in chrome just SS. I want to have it chromed for my project bike. I would prefer if I could somehow get it to work within the standard 1 piece crank setup but may not be able to.
Can I switch to a 3pc setup in my bb and then use the cottered chain wheel?
Im unwilling to switch to cottered entirely.
Ive considered filing the drive pin until its narrow enough to drill a hole for it in one of the...bridge(idk term)
That seems a lil sketchy as far as strength.
Any ideas?

Any help is appreciated
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Starnger

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Well, one obvious way would be to check, if you can make the hole in the sprocket on the distance of the pin on the crank. If yes, then just detach it from the cottered crank, drill the hole and use it with OPC. If you can't drill a hole on the desired distance, for example if it interferes with the sprocket ornamentation, what you can do is to just cut the pin off an existing OPC and weld the sprocket on. When doing that it is important to align the elements perfectly to avoid runout, and to put your weld only to the outside, so the bearing race can be put on the inside tightly. You may as well need to extend the center hole of the sprocket, but for some reason i think it may be same standard diameter there.
 
Nov 6, 2019
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Ya visually it seems very close at least. I havent had it removed yet. From what I read about dealing with cc's whatever it will cost will be money well spent. Just holding that dogleg up to it seems like it should fit in terms of radius but it may need to need to be a bit narrower or I could be dealing with a total failure, I like the idea of welding too, in terms of a fix and aesthetically
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@Starnger

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May 20, 2009
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I would think the following....

IF you can remove the chainring from the cottered crank
and
IF the hole in the center is the same size (if it’s smaller, you could potentially enlarge it, although it could be rather difficult to keep things centered. If it’s larger, then you’ll need a washer/spacer between it and the crank or some sort of ‘ring’ to reduce the hole diameter, again, keeping things centered may prove difficult), remembering the chain line as you go too.

At that point, drilling a hole to support the one piece crank ‘stub’ would be easy.

I say, go for it! Nothing ventured, nothing gained.




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May 20, 2009
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Sorry to highjack your thread, but found this pic on eBay.

It looks like the hole may end up being a little small, you may be able to use a ‘step bit’ to enlarge it or even to separate it from the cottered crank....

Again, go for it!


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Nov 6, 2019
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I I've never seen one separated from the Crank arm does anyone know if they do separate or would it literally have to be ground out.

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Nov 6, 2019
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I dont know if you never see it because it's such a pain in the ... to deal with the pins that people just take off the one side they have to or if they are permanently attached. I do not know

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Apr 18, 2015
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You'll have to do some grinding where the ring is swaged in place, and find someone with a good sized lathe to enlarge the hole- concentricity is important. Probably "easier" to convert the bottom bracket to take a 3 piece set, but finding the right axle length can be a problem.
 
Nov 6, 2019
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Yeah that's great thanks guys it seems like a have several good options. The most low Tech way would be to drill a hole for the drive pin and Totally the way that makes the most sense Mechanically would be to convert to a 3 piece and use it with that. But as usual the most pain in the ... way is the one I think might be the coolest. Cuz if its welded on to use a 1 pc bb, I could use the old school dog leg crank which I like and has the vibe I want plus it would let me show off the chain wheel better by putting the crank arm on the opposite side of the lettering in the exact middle. Almost like the crank arm is the sign post for a chrome JC higgins sign. Instead of having the crank arm in some random spot where it may cover a little bit of the lettering. I'm not saying I'm gonna go that way Because while I think it would be the best way aesthetically, the extra difficulties and one off's neccessary to make it work might end up outweighing how much better I think it would look

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Nov 6, 2019
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Plus the fact that the 1st low Tech way is the only one that I would feel comfortable undertaking by myself either of the other 2 ways I would be out of my depths for sure. I've never owned a single 3 pc bb and I dont weld lol. Then again I cant do the lathe part either so I'd have to outsource some or all of it regardless

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Apr 24, 2007
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If you have a 15/16" drill bit and a drill press. Leave the arm on and use the existing axle hole as the centering guide and drill away. Drilling from the front would get it dead center but would mean drilling through an extra ~1 inch of material (the arm). Drilling from the back side might not get it exactly centered as the swaged bit is never exactly smooth and even. Drilling from the back would mean removing less material.

I have the same crank, still on the original frame. I got the bike in the later 1960s and rode it for years as a winter beater. It's rusted solid now from the salt.

rick