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Old 06-12-08, 05:56 PM   #1
goldmotobecane
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threads are no good on my bottom bracket, but i must save this bike

I have a used Motobecane from the late 70s, i think. it has been riding well for three years, but after a small accident the bottom bracket has become very loose. I took it to the shop and they cannot seem to find a new bracket that will screw in tight enough... the frame looked like it could be re tapped to fit a new bracket, or just held in by some jb weld...the loosness wasnt that bad really and I could still ride around on it alright.

this is worth fixing to me, bc i cant afford a new frame right now, and because i like this frame a lot. and the bike just means a lot to me

so my question is... how can i hold this bracket in place?
will it be safe?

already tried teflon tape...
23" frame...
beautiful gorgeous gold frame, with lots of miles and memories...

thanks for any help
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Old 06-12-08, 06:20 PM   #2
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They can't find a bracket 'cause it's probably french threaded. French threads are very slightly larger diameter than a "standard" british threaded BB and are a finer thread.

Your options are either to find a french BB (35mmX1mm) or get a BB that screws into itself.

http://www.sheldonbrown.com/bbsize.html
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Old 06-12-08, 06:35 PM   #3
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I doubt it is french, since the drive side cup on a french bike is screwed in the oposite direction as a british bike. Maybe swiss?
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Old 06-12-08, 06:36 PM   #4
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might have to go with Italian threading.
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Old 06-12-08, 07:06 PM   #5
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or get a BB that screws into itself.

http://www.sheldonbrown.com/bbsize.html
For exmaple the YST "Threadless" bb, this will save your bike, but the bb is of ultra **** quality. No jokes.
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Old 06-12-08, 07:19 PM   #6
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My old French frame was retapped Italian and I use a 2mm spacer for the extra width.
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Old 06-12-08, 08:44 PM   #7
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I think that a late 70's Motobecane will have Swiss BB threads and I'll bet that someone used British cups. A Phil Wood BB and Swiss rings will save it, but figure about $140. You can watch eBay for a set of Swiss cups and maybe get them for $50. Swiss bottom brackets are the rarest of them all. You can find a shop that will retap the shell to Italian size and use an Italian BB with a 2mm spacer. I have no idea what that would cost.

You have to decide if it's worth it:
http://cgi.ebay.com/Vintage-Campagno...d=p3286.c0.m14

Last edited by Grand Bois; 06-12-08 at 08:52 PM.
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Old 06-13-08, 02:29 AM   #8
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I think that a late 70's Motobecane will have Swiss BB threads and I'll bet that someone used British cups. A Phil Wood BB and Swiss rings will save it, but figure about $140. You can watch eBay for a set of Swiss cups and maybe get them for $50. Swiss bottom brackets are the rarest of them all. You can find a shop that will retap the shell to Italian size and use an Italian BB with a 2mm spacer. I have no idea what that would cost.

You have to decide if it's worth it:
http://cgi.ebay.com/Vintage-Campagno...d=p3286.c0.m14
I'd just retap to italian, it couldn't cost more than $50 to do it at your LBS and now you have a world of options in italian bb's.
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Old 06-13-08, 07:15 AM   #9
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Ill get some estimates and try to have it re tapped at another shop
thanks for all the help
ill let you know how it goes
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Old 06-13-08, 07:28 AM   #10
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one other thing... will my crank and pedals fit onto an italian bracket? I believe they're stock...
if not, is there a way to modify them to fit?
thanks again
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Old 06-13-08, 07:37 AM   #11
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one other thing... will my crank and pedals fit onto an italian bracket? I believe they're stock...
if not, is there a way to modify them to fit?
thanks again
crank will fit - basically it doesn't care about the BB shell threading. But you will have to find a new BB with the correct spindle length. You'll need to measure the length of the one you have now.
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Old 06-13-08, 03:10 PM   #12
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I think that a late 70's Motobecane will have Swiss BB threads and I'll bet that someone used British cups.

I don't know about that. My 1979 Team Champion is French threaded. Will the re-threading to Italian work with French threads, or is that just a recommendation based on the assumption that the threads are Swiss?
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