Since just about everything else on the French bicycle is different, why not the cranks?  Why not indeed!  They, too, have some issues to contend with, but nothing nearly insurmountable.

There are two crank types, or styles, in need of mention - cottered and tapered.

The cottered crank is of Old School design and is secured to the bottom bracket spindle through the use of a cotter pin.  Well two actually, one for each side.  This is hardly unusual for cottered cranks from just about every country sports a cotter pin for each crank arm.  However, it is the size of the cotter pin that bears inspection.

French cotter pins, those that fit the French crank/spindle combination, are smaller than most others by a full half millimetre.  A half millimetre is a lot when one considers the size of the pin itself.  Standard pins are 9.5mm in diameter, while French ones are dead on 9mm.  Needless to say, one will not fit the others application.

The second issue with French cranks applies to both the cottered and, more modern, taper spindle models.  The difference this time is pedal threading.  Yup, the French pedal threads are different from any others.

Standard pedal threads are 9/16" x 20tpi (9/16" is approximately 14.29mm) while French pedal threads are defined in metric terms at 14mm x 1.25mm.  Fourteen millimetres is approximately 0.55 inches, considerably smaller than the 9/16" diameter of the British, Italian, Asian... competitors.  This can, believe it or not create a dangerous situation.

It is impossible (well, not quite) to thread a non-French pedal into a French crank set unless great torque force is used.  Even then, it might not go, and will most likely be very hard to remove.  But it is easy to thread a French pedal into a non-French crank.  The problem is the fit will be very loose.

The fit, to the untrained or uninformed, might seem OK at the time of assembly.  But the fit will prove too loose once the bicycle is ridden.  In fact and in short order, the pedal will loosen off completely, and fall out of its fit into the crank.  This can cause a crash, not to mention the permanently damaged threads that might now be part of the cranks assembly.

It is very common for enthusiasts to have the French cranks rethreaded to the more universal 9/16" x 20tpi pedal thread pattern.  Special metal cutting taps are available however; since the job is, usually, a one time thing, it might be best to just take the cranks to a local bicycle shop, and ask them to do the work.  Once done, most pedals, be they Old School or newer clip in units, will work just fine.

In addition to the pedal thread situation, the threads for the tapered crank extractor are different, also.  A standard extractor diameter is 22mm.  Some French cranks (TA only) sport a 23mm diameter, and some (Stronglight) 23.35mm until 1982.  Great care must be taken when selecting the correct extractor.  The unpractised mechanic might try a 23mm in a 23.35mm fit, only to find the loose fitting extractor will slip, and rip the threads right out of the crank.

Additionally, some French crank bolts, which might be considered part of the bottom bracket assembly, have a 16mm hex head, rather than the standard 15mm, presented by the rest of the Velo world.  The larger bolt head size, on some French crank sets, the Stronglight 49d being a prime example, it is difficult to find a socket that will fit, both the bolt head and into the extractor fit of the crank.  A standard 16mm socket can be ground down to fit into the crank cavity, however, this modified socket will be weakened and should be set aside for crank bolt use only.

As one moves further and further into the unusual restoration challenges presented by French bicycles, one can only wonder why anyone would bother?  Of course, the answer is that French bikes are pretty decent, sometimes.

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