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-   -   convert a chainring? (https://www.bikeforums.net/classic-vintage/469340-convert-chainring.html)

PDXaero 09-24-08 02:30 AM

convert a chainring?
 
I'm looking at getting a cruiser chainring for an old peugeot build-up but would rather not put cottered cranks on my reynolds frame.
SO
is it possible to convert this cruiser chainring to be mounted with cotterless cranks?
I have never heard of a cotterless crank that threads at the center rather than having studs to mount the ring.
Any advice would be of great help.
Here is my proposed chainring
http://www.bikecult.com/works/chainring/chrgpeugeot.jpghttp://i9.ebayimg.com/02/i/001/0e/13/6c5c_1.JPG

stronglight 09-24-08 06:36 AM

If that's an old steel 1/8" Peugeot chainring, it probably weighs a ton already... so I suppose you could weld a steel disc with a narrower diameter opening (40 mm.) into the center, and then drill it for use with an old TA 5-pin or Stronglight 49-d crankset before you have it re-plated in chrome or nickel...

I'd be careful to drill it so the crank arm would exit at one of the points where the arrows meet at the edge of the chainring. With a threaded cottered cranks (like the one shown at the left) this could not be easily done because the threads just stopped the crank arm when it could tighten no more.

infinityeye 09-24-08 10:36 AM

maybe just zip tie it on there?

rhm 09-24-08 11:17 AM

That is a really cool chain ring. I, personally, would be happy to have a cottered crank with that chain ring on a 531 frame; cottered cranks are old school, but they're reliable, and the weight difference isn't as much as you'd think, especially if the arms are comparatively thin.

If you're set on going cotterless, though, I like Stronglight's suggestion you get a pair of TA or similar crank arms (Stronglight 49-d; there's also a Nervar version, something similar by SR or Sugino, and even Lambert / Viscount). With that, you can either (1) have a good machinist make you an adapter that bolts to the crank arm at the inside and threads to your chain ring at the outside, or (2) make such an adapter out of a chain ring that already fits onto the TA &c arms; you'll have to drill some holes through your lions, though, and if you don't do it really well, you'll end up with something like infinityeye's suggestion.

You know, it might be cheaper just to get a 94 BCD crank and have a custom chainring made for it, modeled on your old Peugeot ring.

nlerner 09-24-08 12:19 PM

Hey, if cottered steel cranks were good enough the Raleigh RRA, the Clubman, the Lentons and other 531 frames, why not for yours?! Very cool chainring, btw.

Neal

manofsteel 09-24-08 12:58 PM

Yeah, I'm with Neal... I would get some nice vintage, steel, chromed, fluted crank arms, get your lovely lions chromed to match, and go cottered. What's your reason for not wanting to use cottered?

PDXaero 09-24-08 03:20 PM

I like many others have had bad times with cotters, this may be an indoor and dry weather only bike though so i shouldn't fear the same problems. Maybe people will see cotters and assume its a $50 bike (theft deterrent)

ogbigbird 09-24-08 04:12 PM

yeah, i too have had more bad luck with cottered than good luck. and being ocd that i am, its kinda easy to get them "oblonged", meaning the two crank arms are not exactly "up/down" or even. but if you do have a good set of cottered cranks and access to more keys, goo for it.

Grand Bois 09-24-08 04:22 PM

Just get one of these and you'll have no more problems with cottered cranks. You may actually learn to enjoy working with them. I did.

http://bikesmithdesign.com/CotterPress/index.html

If you don't have the crank that goes with that chainring, I don't think it will be easy to find one.


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