I picked up a free Motobecane at a garage sale.......
07-01-11, 11:31 PM
#1
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I picked up a free Motobecane at a garage sale.......
and am wondering if I can replace the old cotter crank and BB with a modern 68mm square taper. Will the threads match up? The frame indicates the bike was made in France so that makes me think it may have some strange/rare size. This will be my first attempt at working with such an old bike and going in blind, so I appreciate the help.
07-02-11, 05:49 AM
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Yes you can...if you find the correct size bottom bracket cups. I did it way back in 1978. You most likely will have either a Swiss or French threaded BB. FWIW I used Campy cups in mine, because that was what was available at the time.
Aaron
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Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
07-02-11, 05:50 AM
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JensonUSA seems to have a good supply of BB cartridges when you're ready to order...
https://www.jensonusa.com/store/sub/1...+Brackets.aspx
https://www.jensonusa.com/store/sub/1...+Brackets.aspx
07-02-11, 06:13 AM
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Unless there is a problem with the crank, changing to cotterless will degrade the looks and durability of the crank in exchange for a minor weight reduction and some grief/expense in finding a suitable spindle &/cups.
(PS- Pics or it didn't happen!)
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07-02-11, 11:55 AM
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If you decide to upgrade, you may be able find a spindle the right length and just replace that. If you have to buy a bottom bracket and crankset, the cost isn't worth it.
07-02-11, 12:29 PM
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I have done this a few times and I always used the cups that came with the bike, never had any problem.
07-02-11, 01:32 PM
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I don't know what's the hassle with cottered cranks? Loosen up the bolt but leave it on enough to cover up the threads(if you want to save them or sell them) and a few taps with a hammer or mallet. No need to deliver death blows just a few love taps and they always come right out.
07-02-11, 01:55 PM
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07-03-11, 11:21 PM
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After this discussion now I'm thinking maybe just clean it up as best I can and leave it as original as possible. New chain, cables/housing, brake pads, tires/tubes. The frame has some rust on the stays and rear wheel will need to be replaced, but I just happen to have one that will work. I'll have to check ebay and see if these are worth the fixing.....the frame is too large for me.
07-04-11, 05:37 AM
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I don't know what's the hassle with cottered cranks? Loosen up the bolt but leave it on enough to cover up the threads(if you want to save them or sell them) and a few taps with a hammer or mallet. No need to deliver death blows just a few love taps and they always come right out.
I have had to drill a couple out over the years, and that was after trying a cotter press and a large hammer. Not all cotters are going to gently tap out.
Aaron
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Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
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