Bicycle Mechanics - French BB Questions.

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EpicSchwinn
10-13-11, 03:16 PM
Hi!
I'm helping a friend a bit with his first fixed gear conversion and the frame he decided to use is an old Peugeot. I feel a bit like the blind leading the blind here because his bike has a french threaded bottom bracket. He bought a new french BB and is now looking for a single speed crankset. Will this unique/obsolete bb affect what kind of cranks he can use? This is the crankset that would meet his needs best as far as price and features go. (http://www.cyclingcloseouts.com/Products/EighthInch-Crankset-in-White__Eighthinch_Crankset_White.aspx) Would it be usable?

http://www.eighthinch.com/images/products/500h/813315010027-01.jpg
http://www.understandfrance.org/Images/FrenchFlag2.jpg

JohnDThompson
10-13-11, 05:36 PM
No worries.

If the original cups are still usable, all you need is the proper spindle for your chosen crank. If not, Velo-Orange (https://store.velo-orange.com/index.php/components/bottom-brackets.html?bb_threading=31) offers a modern cartridge bottom bracket with French threads.

They also offer a French thread headset (https://store.velo-orange.com/index.php/components/headsets/vo-french-thread-headset.html), should that need replacement as well.
76Crescent
10-14-11, 07:44 PM
The cranks will work. The real question is spindle length. The spindle length effects chain line, and is very important of a fixed gear so the chain will stay on. Most single speed cranks need somewhere in the range of 109 to 111mm spindle lengths. You can usually be off by a mm with little to no effect, so a 110 is usually a good bet. Check with the crankest manufacture for what spindle length they recommend.