Keeping your vintage French bicycle alive in the non French sized world of bicycle parts
Most French bikes used their own standards for the sizing of handlebar stems, bottom brackets, headsets and some seaposts. This became a problem when these unusual size parts became unavailable in the late 1980's.
This makes them a challenge to work on when parts wear out or even worse brake due to fatigue failure. Here at B&L Bicycles we've been creating solutions that allow these bicycles to keep rolling.
Some common vintage brands that used French threads were Peugeot, Astra, Motobecane and Mercier. (There are some modern inexpensively Chinese made bikes with these names on them but they use modern parts and are not made by the original French manufacturers like Gitane, Jeunet, Stella, etc.
French sized Stems
Stems are one of the big problems people run in to, as the stem quill size on most older French bikes used a 22.0 mm size while other bikes used a 22.2 mm size. The 22.0 size is no longer being made which makes it very difficult if one finds oneself in need of a new one for some reason.
We have come up with a solution to this problem. We machine quill adapters down to the 22.0 size. These adapters will work with the modern threadless stems. Since these are so prevalent you can get a stem in pretty much any size and rise you want.
A few notes.
1. The clamping area for the stem on the adapter is 40mm, most stms fit this (some larger clamp designs may hang over a bit, as long as both bolts are clamping over the quill, you are fine.
2. Stems have a minimum amount of the quill that needs to be inside the fork. The quill needs to be insert 70mm into the fork.
3. Most French stems that we have measured were actually made to 21.8mm diameter which allowed them to fit into the forks, as the variances in the production tolerances of the bicycles manufactures at that time often would mean some forks were 21.9 and other 22.0. We have chosen to match the 21.8 size, which we have found on most of the stems we have measured.
4. Always grease the quill when you insert it into the steer tube of the fork.
5. If you have shifters mounted on the quill part of your stem, then you may need a less bulky ahead stem so that the levers don't run into the bolts on the new stem. (See Below)
7. If you wish to purchase the reverse clamp single bolt stem with the French stem quill adapter, (shown in the photo with the Peugeot. This works much better for shifters mounted onto the quill as it is less obtrusive and is less likely to interfer with the shifters) let us know, price is $50.00 and we will cover the shipping.
French Bicycles used different size threads on the frame for the bottom brackets, they were 35 X 1 while English threads are 1.370 x 24 TPI. There are a few high end square taper bottom bracket options like Phil Wood which can be special ordered.
We also have an inexpensive solution if your French bike needs a bottom bracket. We have access to an inexpensive square taper cartridge bearing bottom bracket which are threadless and can be made to work on any frame including ones that have damaged threads. These sell for $26.99. It is best to have the crank and frame here so that we can get an accurate fit. A newer square taper bottom bracket is a good choice for those bottom brackets as many older cranksets used different spindle tapers than what is common today.
French bicycles used many different sizes, some are common and some are very unusual. We make custom seat post adapters to allow for the use of a 22.2 post in frames designed for 24.0, 24.6 and others. Yellow Jersey bicycle shop in Madison, Wisconsin has a custom batch of 24.0 sized seatposts that can be used.