MY "TEN SPEEDS"

 

 

MY "TEN SPEEDS"

 

 

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MY "TEN SPEEDS"  

FRENCH PROBLEMS - INTRO

SIMPLEX PLASTIC

FRENCH TUBING SIZE

STEM & HEAD SETS

BOTTOM BRACKETS

FRENCH CRANKS

WHEEL HUBS

PROBLEMS - SUMMARY

 

BICYCLES OF FRANCE

 

 

FRENCH POST AND STEM DIAMETERS

Since the outside diameters of French bicycle tubing is different from others, are there inside diameter concerns, also?  The simple answer is yes and, once again, the differences being considered are very difficult to see, even with a trained eye.

The two inside diameters that can easily be confused are the steering tube of the fork and the seat tube, accepting the steering stem and seat post, respectively.  There are also French threading issues associated with the steering tube and head set, that one should be aware of, before making a mistake, or worse.

The steering tube of the fork has an outside diameter of 22mm. which is just .2mm less that most others.  Though a very small amount, that extra diameter will, more often than not, prevent the steering stem from entering a French steering tube - properly.  The fit will be just too tight.

It is possible to sand down the 22.2mm steering stem to fit a French steering tube and takes little time to do so.  The question is, would you want to destroy an original, and getting to be hard to find, component just for the sake of convenience?

There is one more thing to consider when considering French stems - the AVA Death Stem, a nick name given to a component prone to catastrophic failure.  The AVA stem was known to snap in half, leaving the rider with absolutely no control over the bicycle.

The second stem issue is handlebar related.  The French stem will accept two handlebar diameters - 23.5mm and 25mm, while other stems support slightly larger diameters - 25.4mm and 26mm.  Once again, it is easy for the uninformed to get into trouble.

Finally, one last and very important French stem issue, however; this issue targets one stem only.  That stem, the AVA alloy unit sometimes referred to as the "Death Stem".  That stem was know to catastrophically fail, snapping in half, and creating what was an interesting situation for the rider, every time it happened.  Interesting?  Crashing would be a better way to put it.

Seat tube inside diameters are also different but so too are many other tube sets from other countries.  Fortunately, there are many different sizes of seat posts to choose from and a decent fit is not all that hard to find at the time of this writing.  However...

The French Peugeot, at least some models, presents its own unique problem.  The seat post fits into a spacer, or shim, which then fits into the seat tube cavity.  Loose the seat post shim and start looking for another one or a reasonable facsimile that will do the job.  Best to not loose the original.

The second issue with some Peugeot seat posts is that they are straight tubes, not shrunk down at one end.  The lack of an reduced end makes it possible for a seat clamp to slip down the seat post, allowing the post to press against the saddle and one's butt.  Not a terribly comfortable situation, to say the least.

Aside from the need for proper threads on the steering stem and head set, the problems are somewhat minor.  Restoration will rarely come to a halt because of not being able to find a steering stem that works.  And, generally with the exception of some Peugeots, fitting a saddle to an appropriate seat post will not be all that difficult to do.

All that said, sizes are still different even though those differences are very small.  Threading is different but so close that the uninformed can, and usually will, get into difficulties.  And those difficulties could well end up damaging the fine threads on the steering stem permanently.

STEERING STEMS & HANDLEBARS
ITEM OTHERS FRENCH
STEM RISER DIAMETER 22.2mm 22mm
STEM HANDLE BAR CLAMP 25.4mm or 26mm 23.5mm or 25mm
FORK STEERING TUBE DIA 26.4mm or 27mm 26.5 or 27mm
HEAD SET THREADING 25.4 tpi x 1.058 mm 25 tpi x 1mm

The next threading issue that does present problems belongs to the bottom bracket.  French bottom brackets have different threading from most, if not all, others.

NEXT - THE FRENCH BOTTOM BRACKET

 

 

 

 

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