French Bicycles Posted on 21 Jan 08:00 , 0 comments
From the name of our shop, you can guess we have an affection for French bikes. Until the 70’s the French were renowned for the manufacture of elegant, if quirky cycles. By the 70’s they were more mainstream and exporting millions of their machines, all over Europe and the USA. Peugeot were the major protagonists but Motobecane, Lejeune, Gitane and many others were popular as well as many smaller “lightweight” builders producing racing bikes.
The French always like to do things their own way and their bikes were no exception. At the beginning of the cycling boom in the late part of the 19th and early part of the 20th centuries, different countries and different manufacturers had their own standards for cycle components. However, by the 1930s, standardization was emerging, based principally around the imperial BSA standard screw threads and sizes. There were exceptions of course: Raleigh the world’s largest manufacturer, who at that time made pretty much every part of a bicycle in their own factory, saw no reason to abandon their own unique standards. The French of course stuck steadfastly to their own Metric interpretation of the standards, until the early 80’s when they gradually adopted the British BSA standard for most components. The major exception is French tyre sizes which are now dominant in most parts of the world. 700C and 650B are old French standards of course.
So what is different about these French machines that is likely to trip you up? Mainly it is the screwthreads used on pedals, headsets, freewheels and bottom brackets. The French used a 1mm thread pitch (i.e. 25.4 threads per inch) rather than the (now ISO) standard 24 tpi. Similarly the diameters were metric equivalents. For example a bottom bracket shell is 35mm rather than 1 3/8”. Close enough to confuse the uninitiated and to enable standard ISO components to be fitted with application of force.
French pedals are so similar to standard ones that they can be forced into a French crank, like a T.A. , Stronglight or Nervar. This is often successful, but I have seen cranks that have been split open by doing this. There is an easy solution to this: French threaded cranks can be easily re-tapped to English standards by any bike shop. French pedals are unavailable now so this is a necessary upgrade when your pedals need replacing.
The French thread standard for screw-on freewheels is so close that a standard freewheel can usually by screwed on without much difficulty. Very occasionally this will result in the freewheel thread being stripped, but I have only ever heard of 2 examples of this. You can’t get new French threaded freewheels so it is worth a try – otherwise a new hub is called for.
French headsets very nearly the same size as ISO, except for the screw thread. The good news is that Velo Orange now manufacture a French threaded headset at a very reasonable price. If you have a French tandem, the news may not be so good but there are solutions, please visit my peugeottandem.com website for answers.
In theory standard 1” (22.2mm dia) stems won’t fit in a French threaded fork steerer. In practice they do, so this is not a problem.
(see my Bottom Bracket blog post)
This is the big difference. Apart from the metric thread, both cups on a French threaded bottom bracket are Right Handed threaded and the locknut is on the right hand side. The only solution to this is to fit a Velo Orange French Threaded Bottom Bracket
The French had their own wheel and tyre sizes, the most common on surviving bikes are 700C, 650B, 650A and 650C. Rims and tyres are available in these sizes and 700C is now the standard for road bikes and some MTBs (otherwise known as 29’ers). 650B is enjoying a resurgeance as 27.5” on some MTBs. 650A is the same as the old British 26x1 3/8” standard used on most utility bikes of the 50s, 60s and 70s. 650C is used widely in triathlon bikes.
There are also other minor differences with French bikes e.g. mudguard attachments etc., but these are easily overcome with a little ingenuity.
Enjoy your lovely French bike!