Author Topic: French cottered cranks -I owe Brucey an apology  (Read 357 times)

French cottered cranks -I owe Brucey an apology
« on: July 24, 2020, 11:36:05 pm »
This post is about historic stuff so if it's not your thing don't bother to read on.

A while back on an unrelated thread IIRC we had differing views on the dimensions of french bb spindles, me saying that they would not fit english cranks and Brucey saying the opposite. Yesterday evening I decided to have a look at my "vintage " machine which had a lot of radial play on the ds of the bb. This bike has an old Stronglight racing cottered chainset, complete with hollow spindle. The nds has the correct cup, the ds has to work with the original in the frame since I haven't yet resorted to extreme sanctions to remove it (and I don't have the octagonal form spanner to do the job properly).
While I had the cranks off I decided to try them on an english spindle - just for the fun! Surprise, they fit. Another one, same thing. Oops, sorry Brucey. I shouldn't have doubted you! For the record I suspect that the fit wasn't quite as close as I remember an english crank should have been but don't have one to check.
Obvious question - what happens with one of those french spindles that I reckoned would not take an english crank? I have a suitable spindle - well what do you know, it won't go!

So the moral is if  you are working on an old (probably up to 70's) french bicyclette that might have found its way to UK (most likely cases would have been folders and 550A small framed "kids" bikes) take care when mixing and matching bb components. My old stuff is probably pre-1960 but I am not sure when things changed.
How like the french to have two spindle diameters at the same time! Must check the cotterpin diameters.

LittleWheelsandBig

  • Whimsy Rider
Re: French cottered cranks -I owe Brucey an apology
« Reply #1 on: July 25, 2020, 08:52:45 am »
Most cotterpins are 9.5mm. French and Italian are usually 9.0, sometimes 8.5.
Wheel meet again, don't know where, don't know when...

Re: French cottered cranks -I owe Brucey an apology
« Reply #2 on: July 25, 2020, 12:37:36 pm »
FWIW maybe it is premature senility on my part, but  I don't remember saying that, not quite!

  IME French and British spindles are usually slightly different diameters, such that you can use a mixed combination in some cases, provided you are happy to tolerate a poor quality fit between the parts (which you shouldn't be unless desperate). I suppose that slightly worn parts might go together in the other combination too, and of course cranks can have been made differently or modified after manufacture too.

Strictly speaking BS cotter pins are 3/8" dia (9.525mm) I think but 9.5mm is close enough bearing in mind that any you can find to buy new are such lousy quality.... 9mm cotter pins in most French stuff.  I've heard tell of 8.5mm cotter pins but have not had the 'pleasure' in person as it were.

BTW if you take an old French BB, often the shoulder distance on the spindle is smaller than many other BBs, such that most BB spindles won't work with the original cups. However it turns out the shoulder distance is quite close to that found in 'Neco' three-piece BBs, which often allows you to fit a cotterless chainset to a French-threaded frame, using the original BB cups with a Neco spindle.

cheers

LittleWheelsandBig

  • Whimsy Rider
Re: French cottered cranks -I owe Brucey an apology
« Reply #3 on: August 02, 2020, 09:25:25 am »
There are a few decent cotter pins out there. http://www.bikesmithdesign.com/CotterPress/cotters.html suggests that the French still produce nice cotter pins but I have only ever bought them via the USA, along with a press.
Wheel meet again, don't know where, don't know when...