French bicycles are often of very high quality, but they have their own idiosyncracies and interchangeability problems. This article tries to point out the pitfalls that you may run into in maintaining or upgrading a French bicycle, and offers solutions to common problems.

In the great bike boom of the early-mid '70's, French bicycles were sold in the U.S. in very large numbers, mostly low-end ten speeds with mild steel frames, steel rims and cottered cranks. These low-end models are generally not worth putting any money into, unless you have a strong sentimental attachment to one. Such a bike can be suitable for use as a "beater" to ride short distances, perhaps to the train station where you can lock it up without worrying about theft.

[A note from John Allen: I think that Sheldon overgeneralizes here. Some of the low-end models make for a very nice ride if customized with better components. I'm not the only cyclist who praises the excellent handling qualities of the UO-8, Peugeot's bottom-of-the-line 1970s 10-speed. There are probably other low-grade French bicycles as good. The UO-8 frame has unusually long chainstays, for ample heel clearance when carrying rear panniers. The plain-gauge steel frame tubing is a bit heavier than fancier butted tubing, but the added stiffness is welcome when carrying a touring load, and plain-gauge tubing doesn't dent easily like thin-walled butted tubing. A UO-8 is my favorite touring bike. So there!]

Higher quality French bicycles, with cotterless cranks and aluminum rims are usually worth restoring or upgrading. These bicycles are also often a good choice for conversion for fixed-gear use. Unfortunately, some of the dimensions and thread standards used on older French bicycles can make it difficult to find suitable parts for repair or upgrading.

[Also in connection with this article, see Sheldon's article on upgrading...John Allen]

French stems differ both in the size that fits into the steerer, and the size of the part that clamps on to the handlebar. Thus, if you want to replace the handlebars on a French bicycle, you will probably also need to replace the stem.

French stems are 0.2mm narrower than others where they fit into the steering column. A standard 7/8" / 22.2mm stem won't usually fit. In many cases, the limiting factor for fitting the stem in will be the headset locknut, rather than the steerer itself. Try removing the locknut before sanding down a stem. If the headset locknut is slightly tighter than the steerer, it can be enlarged easily with a small grinding wheel.

In cases where the stem really won't fit into the steerer, a few minutes' work on the stem with sandpaper will usually do the trick. Wrap the sandpaper around the stem, grip it with your hand, and turn the stem round and round until it fits. You only need to remove 0.1 mm, which is 1/250", not much at all! [This needs to be a quill-type stem, which inserts into the steerer tube, and an aluminum alloy stem, not a steel one -- from which you would be removing chrome plating, leaving it vulnerable to rust. Another approach is to replace the fork and the headset with ones with standard British/ISO dimensions. This is possible, as French head tube bearing race dimensions are 30.2mm, the same as British. You could use a standard 22.2 mm quill stem, or a threadless headset and a 1-inch Aheadset-type stem. Also, an adapter is available as of 2014 to fit a 1 1/8" Aheadset-type stem to a French fork.-- John Allen]

If you convert from a French stem to a standard one, you will also need to replace the handlebars, which are a different diameter.

French headsets use a different type of keyed washer than others. Instead of having a groove machined in the threads, the rear part of the threads is filed flat. French headsets commonly used a serrated keyed washer, with matching serrations on the threaded bearing race. This makes French headsets slightly harder to adjust, but once they are adjusted, they hold their adjustment better than conventional designs.

French bottom bracket cups usually have thinner walls than Japanese ones, so the bearing ridges on the spindles are farther apart. If you use a standard Japanese spindle, the adjustable cup won't be able to screw in far enough to snug up the bearings, or if it does, it will sink into the bottom bracket shell so that you won't be able to install the lockring.

The good news is that a Japanese spindle made for an Italian size (70 mm) bottom bracket will usually fit! In the J.I.S. marking system, these are the spindles that are marked with a "5" code. Spindles for 68 mm bbs have codes beginning with 3. This trick often makes it possible to upgrade an older bike from cottered to cotterless cranks, at a reasonable cost, or replace a worn French cotterless spindle that is no longer available -- but see warning below about French crank extractors.

Few cartridge bottom brackets are available in French thread, but Phil Wood retaining rings are available in French size. They work with Phil Wood bottom brackets and Shimano UN72 units. Velo Orange makes a cartridge bottom bracket which uses expanding sleeves instead of threads, and also will work in a French-threaded frame.

French-thread bottom brackets, like Italian, use regular right threading on both sides. This means that the fixed cup will have a tendency to loosen up in use. The best prevention is to make sure it is really tight. In some cases, a thread adhesive may even be called for.

Some French bicycles, notably many Motobécane models, used Swiss thread bottom brackets. These have the same thread and diameter as French, but use a left thread for the fixed cup. This makes life interesting when you need to remove the fixed cup and don't know which way to turn it. Good luck. Phil Wood and velo Orange offer the same options as with French bottom brackets.

Newer French bicycles commonly use Italian or British/I.S.O. bottom brackets.

See the selection of French bottom brackets and parts at Harris Cyclery.

Older TA and Stronglight cranks each had their own unique thread for for the crank extractor, and you will need to get the correct puller for the crank you are working on. TA used a 23 mm extractor, Stronglight used 23.35 mm until 1982, when it converted to the standard 22mm diameter. You must use the correct crank extractor. Be especially careful not to use a TA extractor on a Stronglight crank. It will thread in, but it may strip the threads in the crank.

Some J.I.S. Japanese spindles have studs on the ends threaded for nuts to hold the cranks in place, instead of bolts that thread into ends of the spindle. Many TA or Stronglight crank extractors do not work with a stud-end spindle, because the plunger can not be retracted far enough. You could use a gear puller (sold at auto parts stores) to remove a crank if you don't have an extractor that will work. Next time, use a bolt-type spindle!

Older Stronglight cranks used bolts with a 16 mm head. The common Park crank bolt wrench [unfortunately no longer made] will turn these, but most other socket wrenches will not fit inside the extractor hole. Use only bolts with a 14 or 15 mm head in a crank with a smaller extractor thread diameter.

The vast majority of French bicycles imported into the U.S. used standard 9/16" x 20 tpi crank threading, but if you find an older bicycle that was bought in France, you may run into this problem. The French-thread cranks can be tapped out to 9/16". This is much easier (and more worth the trouble) with aluminum cranks. Start the taps from the inside of the cranks, so any possible thread damage occurs where it doesn't matter. French pedals will often be marked "G" (Gauche=left) and "D" (Droite=right).

French-thread freewheels used a smaller diameter attachment to the hub. Neither the freewheels nor the hubs are interchangeable with anything else. Fortunately, they are quite rare: virtually all French bicycles sold in the U.S. had standard British/I.S.O. freewheel threads. In any case, unless you are restoring a collector's item, you will do well to spread the rear dropouts, and upgrade to a modern rear wheel with a cassette hub and index shifting -- see my article on frame spacing.

Both hub flanges were 1mm farther to the left than those of a normal hub, causing increased dish in the rear wheel, and persistent spoke breakage problems. Many loyal Helicomatic fans tout the ease with which the cassette may be removed for spoke replacement as a great virtue, but if the hub were better designed, it wouldn't break so many spokes!

These hubs were prone to bearing problems as well. Due to clearance requirements, they couldn't fit the normal 9 1/4" bearing balls, so they used 13 5/32" balls on the right side. These didn't hold up well. The cones tended to wear rapidly, and replacement cones are no longer available to fit these hubs.

The better models, those with Reynolds 531 or other high quality tubing, commonly featured Simplex forged fork ends, with built in Simplex-type derailer hangers. These are not the same as the Campagnolo- and Shimano-type hangers used on modern bicycles. It is possible, however, to modify Simplex hangers. They have an unthreaded mounting hole, which may easily be tapped out to the standard 10 mm x 1 mm thread used by modern derailers. Standard derailer hangers also have a step at the bottom edge which limits the forward swing of the derailer. This can usually be supplied by judicious use of a file. Its angle may differ depending on the derailer. If the derailer hanger can't be made to work, you might remove it and braze on one that does, or use an adapter claw.

• U.S./British 14 gauge (.080", 2 mm) is the same as French 13 gauge
• U.S./British 13 gauge (.092, 2.3 mm) is the same as French 15 gauge

Fortunately, though, the thickness of most spokes is by now labeled in millimeters. When in doubt, measure! Spoke threading also may differ, so always get new spoke nipples to go with new spokes.

Bicycles built for the French market and informally imported generally use one of 3 tire sizes:

• Sport bikes would use either tubulars or 622 mm (700 C) clinchers.
• Utility bikes, loaded tourers and tandems would generally come with the 584 mm size commonly known as 650 B or "demi-ballon." This latter size has traditionally been quite difficult to find in the U.S., and is an endangered species in France. Schwinn used this size on a few MTB models. In Schwinn nomenclature, it is called "26 x 1 1/2".

  The 584 mm (650 B) size is recently making a bit of a comeback! See my article on 584 mm/650 B wheels.

  There is a French organization dedicated to preserving this size: La Confrérie des 650B

• Some French folding bikes use 490 mm (22 X 1 3/8") tires. There are also several other specific French sizes used mainly on juvenile bikes.