The Chainlink

Last fall I purchased a late 70's Mobobecane three-speed, wiith a step through frame and matching fenders.  It had been sitting in a suburban garage for 20 years and cost me $50.  I got it turned up and put new tires and a new seat on it, plus a frnt basket.

 

I then proceeded to ride it through the winter.  The bottom bracket and cottered cranks are now pretty much done for.  I recently got them tightened and they only lasted about 2 weeks before becoming completely loose.

 

My bike shop said that they could put a universal bottom bracket in there and a modern crankset...but this would be kind of pricey. 

 

At this point, I'm wondering if I should cannibalize the parts that I put into this onto a different frame, or if I should just put the money out for the bike.  I like it, but I wouldn't say that I'm in love with the bike, but I do like the step through frame and have had difficulty finding women's frames that are tall enough for me.

 

What should I take into consideratio when making this decision?

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Replies to This Discussion

I suggest that you have the Motobecane fixed, especially if you like the frame. That just seems like less of a hassle compared to finding a new bike and transferring all of the parts. You can buy a new french threaded bottom bracket for about $50 from Velo Orange and you'll probably never have to service it again.

Then again, i'm sure a number of people in this group have spare French BBs if you want a used one.
If it's only the BB cups that have come loose, it's not a big deal. French threaded fixed (drive side) cups (and some Italian-threaded) like to come loose from the bearing pressure against them. That can be remedied by using a dab of red Loctite or similar adhesive on the threads when reassembling them. Loose cottered crank arms merely need to have the cotterpins smacked back in with a hammer and their lock nuts tightened up -easy fix. For a loose adjustable (non-drive side) cup, make sure the cup/BB is adjusted and the lockring is tight and put a small dab of green Loctite on the lockring threads.

i used the Loctite solution on my 40 year-old Peugeot's fixed cup. Hasn't loosened up yet in over 5K kilometres.
If you decide to replace, be sure to verify whether or not the Moto actually has a French BB. From what I understand, some had Swiss BBs as well - that may be the case if your LBS recommended a threadless BB.

I did put one of those Velo Orange French BBs on a Peugeot U08, and it is smooth.

The other consideration I can foresee is - does the Moto 3-speed have a chainguard? If so you'll need cranks with a chainring of a similar tooth count in order to clear the chainguard and give similar gearing.

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