Bicycle Mechanics - Can I Replace the Spindle in a French Bottom Bracket and Use the Same Cups?

I bought a bike off CL for $30, I think it's a Motobecane. It is completely unmarked except for the chrome winged W at the top of the fork. I don't know if it's a French or Swiss bottom bracket, I guess i should know if I want to take it off.

Anyway, this bike I think was never ridden. The teeth of the freewheel are unmarked. Most of the steel components have lots of little rust spots, I guess just from sitting for so long, but the chainring teeth look unused also. The bottom bracket feels OK, not completely smooth, but definitely usable. From the lack of wear on the bike I'm guessing that when I take it off there will be no wear on the cups, just no grease. It's probably completely dried up.

I don't like cottered cranks. Also the big chainring is a little bent. I would like to replace them with some Shimano 105 cranks I have laying around. Can I stick an Octalink spindle in there while still using the original cups? How about a regular square taper spindle? what length would it need to be?

I don't think this is a particularly great bike, considering the lack of lugs everywhere except for the front, and the cottered cranks. But it's pretty lightweight for a beater and with the brake arm clearance will let me put on some knobby tires for snow riding.

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If you dont have a problem with the size of the bearings I dont see why you can't.

Oh... correction, missed the octalink part... HIllrider is right.

No, you can't use an Octalink or any other cartridge bottom bracket with the original cups. Almost all cartridge bb's have the threads on the cartridge itself or the loose cups have a specific inside diameter to fit the cartridge.

However, you can find complete cartridges with French or Swiss threading. Velo Orange sells them in French threading and a threadless version that will work in a Swiss threaded shell, all square taper in a variety of length and, I believe JIS taper. Phil Wood sells square taper cartridge bottom brackets in a huge range of spindle length and tapers and offers every cup threading known to man. The VO cartridges are pretty reasonably priced and the Phil Woods are premium priced but a long term purchase.

As to plain spindles, you may be able to find one that works with your existing cups but good luck finding one. Harris Cyclery, the bastion of the odd and obsolete, no longer offers them. Loose Screws still has a Suguino Maxi that should work but in 124 mm length only which is probably too long for most newer square taper cranks.

http://www.loosescrews.com/index.cgi?d=single&c=Bottom%20Bracket&sc=Spindles&tc=&item_id=SU-3S&id=581072525467

thanks. what makes that spindle different from any other with a 52mm center? why would this fit an english or french bb, but other ones that fit english, wont fit french?

thats pretty cheap. i am converting this to single speed. so it doesnt really matter how long it is on the right side, actually it just might save me the trouble of dishing the rear wheel

thanks. what makes that spindle different from any other with a 52mm center? why would this fit an english or french bb, but other ones that fit english, wont fit french?
I don't know why other plain spindles intended for a 68 mm shell won't work except some cups are thicker than others and that may be the problem. LS says this works with any cup. The 124 mm overall length may give you chain line problems with a newer crank which is particularly an issue with ss/fixie gears.

Edit: If you were referring to the other spindles shown by Loose Screws, they are for 73 mm or 70 mm bb shells, not the 68 you have.

gotcha. i'll send LS an email and see what they have to say about it. thanks again for the link.

The winged W's on the folks are really M's and thus the folk is a Motobecane. Likely the rest of the frame is also. It is a decent bike overall. Many folks have a lot of problems with the cottered cranksets. If your intent is not to restore back to vintage original, then you could be money ahead to just get a modern French threat BB and a decent crankset off Amazon and pedal on more reliably. I have heard of French bikes with non-French BB's so be sure to confirm facts before investing in parts. I can't help much with carbon dating the bike, but I can add that I have a Sprint Tour model from early 70's that came with a modern square taper aluminum crank several years newer than a cottered crank.

Velo-Orange has made threadless bottom brackets for some time, also has French (Sheldon carries them). There are now other brands as well, and they would be the affordable option if you have Swiss threading (vs. the pricey Phil Wood option). A Google search will yield at least 3 different brands.

loose screws told me that any spindle with a 52mm center dimension should work with the existing cups. i'm gonna try it!

loose screws told me that any spindle with a 52mm center dimension should work with the existing cups. i'm gonna try it!
Buy it soon. The owners of LS are retiring and closing down their business so what they have in stock is available but nothing more will be ordered.