Have I got a French threaded hub?

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daccordimark

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Hi,
I've got an old pair of wheels with Maillard Normandy large flange hubs which I want to use on my current project. However, when I screwed the Regina freewheel onto the rear one it seemed quite loose on the threads. The same freewheel is nice and tight on a Campag hub so is the Maillard hub French threaded? If my reading of Sheldon Brown is right it probably is French - can anyone confirm that for me?

Cheers,
Mark.
 
I think it's likely you have a French threaded hub.

The diameter of French threads is quite close to BSC, and Campag hubs can have Italian (35mm x 24tpi) threads, so the fact that a given freewheel is a snug fit on a Campag hub and a looser fit on your Maillard hub doesn't necessarily mean the Maillard hub is French threaded. You really need to measure the pitch to be certain.

If you don't have a thread guage, try eyeballing the Maillard hub's threads against a known 24tpi thread (e.g. a left hand BSC bottom bracket cup, or your Campag hub), and a known 1mm pitch metric thread (e.g. an M6 bolt). A mismatch will be fairly clear: the threads will fail to mesh together over a distance of ten threads or so.
 
The few times I have come across French hubs is when the freewheel goes on a few turns and then gets stuck!! The French hubs seem to have the threads more tightly together / finer.

Shaun
 
Midlife":q8h92w1k said:
The few times I have come across French hubs is when the freewheel goes on a few turns and then gets stuck!! The French hubs seem to have the threads more tightly together / finer.
Click to expand...
It's a few years since I've played with French-threaded hubs, but my recollection is that a BSC freewheel is loose on a French hub. The French metric pitch is a touch finer (25.4 tpi (1mm pitch) vs 24 tpi), but the small difference in diameter gives enough play that the fit feels notably sloppy.

Here's Sheldon (may his memory be blessed):

A French freewheel may start to thread onto an ISO/British/Italian hub but will soon bind. An ISO/British/Italian freewheel will skim the top of the threads of a French hub and will slip forward if an attempt is made to use it. Do not force a freewheel - you will ruin the hub.

http://sheldonbrown.com/freewheels.html#threading
 
Thanks guys, having done the eyeball test and run a BSC lockring over both hubs it's pretty obvious that the hub is French threaded.
In fact thinking about it the wheels came off a Gitane a very long time ago which was French everything apart from the pedal threads in the T.A. cranks.

Cheers,
Mark.
 
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