Re: [CR]New French-thread cartridge BB for Motobecane?

(Example: Framebuilders:Masi)

In-Reply-To: <8595-44BEC987-352@storefull-3272.bay.webtv.net>
References: <8595-44BEC987-352@storefull-3272.bay.webtv.net>
Date: Wed, 19 Jul 2006 23:06:14 -0400
To: theonetrueBob@webtv.net (Bob Hanson), classicrendezvous@bikelist.org
From: "Sheldon Brown" <CaptBike@sheldonbrown.com>
Subject: Re: [CR]New French-thread cartridge BB for Motobecane?
cc: r4959l@msn.com

Richard Long was quoted in part:
>"... I consulted the Harris section on French bikes and found the truth
>of the bracket. French!!

You sure? Most Motobécanes have the even scarcer Swiss threading on their bottom brackets.
>Since the crank is already Japanese (SR) I thought I might use
>a Shimano 600 I have collecting dust.

That will very likely work, only question is whether the chainline will be acceptable.
>I need help with this one,

Try it! What have you got to lose?

Bob Hanson wrote:
>
>Although I know Stronglight (and Speidel) DID make some French threaded
>cartridge bearing sets by the late '70s / early 80s these are tough to
>find, and very expensive, and would likely NOT fit a Japanese crankset.
>I'm afraid that French threaded bottom bracket cups (for the most part)
>have not been produced for almost 25 years.
>HOWEVER, you can still buy a beautiful new Phil Woods cartridge bottom
>bracket and can specify French threaded lock rings for it - Sheldon
>Brown has these available at Harris Cyclery.

Thanks! By the way, there's only _one_ Phil Wood.
>
>Unfortunately, it's not a cheap way to go. Figure maybe $100 - PLUS the
>cost of the pair of the French thread lock rings, PLUS cost of a pair of
>the Phil's unique splined lock-ring tools - which are similar to
>Shimano's splined BB socket tools... uh... only different.

Actually, it's the other way 'round...Phil was making cartridge bottom brackets at least a decade before Shimano got into the act. It was Shimano who chose to use a different spline.
>And, to use your dust-gathering 600 crankset, Sheldon would probably
>have to know EXACTLY which model this is, as the spindle length (as with
>the Japanese specific tapers) for a specific Phil Wood BBs would depend
>on this.

The only issue is chainline and clearance. The way to proceed is to install the crank, measure the chainline and check the clearances. If they're OK, all is well. If not, it's easy to determine how much longer or spindle a replacement spindle would need to be.

See: http://sheldonbrown.com/chainline

and: http://sheldonbrown.com/bbsize
>
>If you're really wanting to replace the BB anyway, you might just want
>to consider a Phil Wood BB... AND, a "different" completely new
>crankset. Perhaps something really Kool, and one best suited to both
>the bike and to the type of riding you'll be doing on it.

Might be worthwhile depending on the model of the bike. I'm afraid I didn't see the original posting, 'cause Bob apparently broke the thread by changing the Subject heading...maybe that mentioned which model Motobécane it is...
>~ Other alternatives would be [and, I'm sorry, but I can't remember now
>whether you'd initially said that your original BB was totally shot] :
>
>1.) Have your frames BB shell re-threaded to accept a more common BB.
>It can be done by a competent framebuilder or a top notch bike shop,...
>BUT, would you really want to mess with this now on a newly re-painted
>frameset?

This doesn't actually require great skill, but does require expensive tools. Also, older bikes with pressed steel BB shells may not have thick enough walls to do this. (The usual way to go is to machine it out to take an Italian thread bb, a husky 36 mm vs the 35 mm used on French and Swiss.)
>
>2.) Keep the existing BB and see if the Shimano 600 crankset will fit
>"adequately" on this, for now.

That would be my first choice.
>3.) Use the original BB and the original crankset - until the
>questionable crank finally just busts apart.

Might be reasonable, as far as I can tell from Richard's description.
>4.) If necessary, buy a new "TA" French threaded NON-cartridge set ~
>again, from Sheldon.
>
>5.) You can often find NOS vintage French-threaded BBs on eBay, ... or
>perhaps also from other List Members, as well.

6.) Keep the existing BB _cups_ and replace the spindle.

By the way, many folks don't know what "Motobécane" means...

The company manufactured both motorcycles and bicycles.

The French word "moto" translates as "bike" referring to a motorcycle.

The French word "bécane" translates as "bike" referring to a bicycle.

Sheldon "Bikebike" Brown +------------------------------------+ | France, France...if not for you, | | the world would be alone! | | --Victor Hugo | +------------------------------------+ --
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