Tuesday, March 4, 2008

Bottom Bracket Fun and Games

Took the Gitane frame, fork, headset, bottom bracket and crank into my LBS to start putting it back together. Mechanic Mark was dubious about the compatibility of the crank (Stronglight Impact compact double 48/34) and the bottom bracket (Sugino 113mm square taper asymmetrical spindle, old, French cups). He was right. There is "old" square taper (the spindle) and modern square taper (any Shimano compatible square taper bb).

"Get a new spindle". Right. It needed to be 110mm and symmetrical. And the proper generation of square taper. French-threaded bottom bracket, remember? Can't just plop a standard cartridge bb in there.

The easiest, and most expensive solution is to get a Phil Wood bottom bracket, with French cups. I could leave that to my grandchildren in my will.

After much searching on the internet, I started seeing references to Shimano cartridge bottom brackets and the Phil Wood French cups. There exists a generation of bottom brackets with both cups removable, not like the current ones.

A tense time on eBay, and the Shimano UN-72 bottom bracket is mine. The spindle is perfectly compatible with the crank:

And wikipedia, (Section 3.3) as well as other sites list this bottom bracket as one with removable cups.

The Gitane forum guys recommend this method as well.

I'm sure there will be other surprises and challenges to work though.

Stay tuned. This bike may be rideable by sometime in April at this rate.

1 comment:

Tv wall brackets said...

I want to purchase one of these wondering if it's compatible with the Campagnolo 10
drivetrain? Also if the taper of the Stronglight Crank will fit the square
taper of a Campagnolo 111 bb? what do you think? I think it might but i dont want to invest in something that wont be perfect you know what i mean?

Great post!