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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 06-12-06, 10:23 AM   #1
olderlearner
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replacing Stronglight crank with Campy: Problems?

I'm a new poster here. I am restoring a 1973 motobecane grand record, and its looking pretty good. The chain slips off the largest gear of the freewheel, and I figure they just both need to be replaced. I got an old atom french thread freewheel on ebay, and I'll get a chain too. When I watch the largest gear wheel turn I can see that it does not turn in a perfectly flat plane, so it rubs the side of the front changer. I'm thinking the gear wheel is slightly bent. I'm wonding if I can stick a campy crank on the stronglight axle, or will the two have compatible angles or dimensions or something. Has anyone had any experience putting campy cranks on a stronglight axle? I know every other component on this bike has odd sizes, why should the axle be any different?
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Old 06-12-06, 06:30 PM   #2
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I'm a little confused about your terminology. The freewheel is attached to the rear hub. It has the 5 variously sized gear cogs on it. There is no French threading. The bottom bracket could be French threaded. The cranks attach to the bottom bracket spindle and the chain rings attach to the cranks (the crank spiders.) The axle is also part of the rear hub assembly. The cranks attach to the bottom bracket spindle.

With that terminology out of the way, it sounds like the problem you are describing is with the chain rings. If they are bent you can either straighten them or replace them. Just be sure you get chain rings that fit the crank spider. Measure the difference between two adjoining bolt holes center to center. That's the measurement you need. The brand doesn't matter as long as they fit the spider. Putting new cranks or cranks of another brand on an old bottom bracket may or may not work. No way to tell from your description. The guys in the Classics forum may know off the top of their heads. Finding a French threaded bottom bracket may be a challenge so you might want to restore what you have with new bearings etc if that is what is required.

I recently restored a 1980 Moto Mirage. I had to replace the rear wheel and freewheel. I was lucky in that I could simply clean and rebuild the bottom bracket and crankset. The bike rides just like it did 26 years ago. Good luck with the restoration.
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Old 06-12-06, 06:40 PM   #3
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Yes, you can replace the Stronglight crank with a Campy NR/SR and use the same bottom bracket. That's what I did on my PX10.

http://community.webshots.com/photo/...8014369GxvdEs#
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Old 06-13-06, 02:29 PM   #4
olderlearner
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I was referring to two seperate problems. The freewheel/chain are both worn. The freewheel is an atom and threads onto the rear hub and is removed by a freewheel puller that is specific to atoms, with 20 or so teeth that fit the inside of the freewheel. I suspect both the remover and the threads of the freewheel are specific to either French wheels or atom freewheels.

A seperate problem is the apparent bend in the chainring. I don't know which is bent, the chain ring or the spider arms. Thought I'd just replace both to be sure. There are a few campy french BB thread cups on ebay, but they are not cheap. There are a few stronglight cranks, with attached chain rings and spiders, which would be an easy swap. I might go that way. Its ridable right now, and its a head turner. Thanks for the comment.
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Old 06-13-06, 02:31 PM   #5
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Dirtdrop, that is beautiful. Now I have to have one. Thanks!
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