------ Thus sayeth Brother Harvey....
>
> I know two series of Nervar alloy chainrings. One type used
> the 50.5 (?) mm 5-pin circle like the Stronglight 49,
> Williams, TA, etc. These sound like the other type, the
> Nervar Star 5-arm. You will want to note that these use a
> unique bolt circle that doesn't interchange with
> anything else known to mankind. Close to Stronglight 63/93,
> if I recall correctly, but no cigar. However, with a little
> time with a rat-tail file, I was able to adapt them to fit
> something else, back in the day. Worked fine, on a kid-back
> tandem I set up. I'll check the BCD when I get home.
Now... here is the incredible truth about the bolt circles used on Nervar cranks. Many of you will not believe some of what follows, but - if necessary - I can provide photographs :-)
In any event, when selling Nervar chainrings, I believe it is imperative to measure the bolt circle and then specify it when you list them for sale. The late, great Sheldon Brown shows you how to do it:
http://www.sheldonbrown.com/
So here is the sordid truth about Nervar rings. There are actually THREE different bolt patterns. In the snipet above, Harvey mentions two: - 50.5 (?) mm 5-pin, which interchanges with many "old style" 5 pin cranksets such as T.A., Stronlight 49d and Williams. This is what you have on the 5 PIN style Nervar Star cranks.
- 128mm 5 bolt, which is the "classic" Nervar 5 bolt pattern, and which is unique to Nervar. This is what you see on the 5 BOLT style Nervar Star cranks.
There is another pattern, used on the last of the Nervar cranks: - 122mm 5 bolt, which is the same as Stronglight. These are found on some of the "aero" style Nervar cranks that appeared on numerous early 1980s Peugeot and Motobecane bicycles. (Maybe on some Gitanes, too?)
I discovered this after purchasing an entire Peugeot bicycle merely to acquire the chainring set. I was truly surprised when the rings did not fit my Nervar Star cranks. Then I measured the cranks on my old Peugeot PGN-10 and discovered that it too used these 122mm rings.
Anyway, the most astounding part of all this situation is that Nervar adopted the 122mm pattern after Stronglight had abandoned it. (Perhaps "adopted" is too strong a word, as it is possible that this last style of Nervar cranks were made for both 122mm and 128mm, depending on the date of manufacture.)
In conclusion, the important thing with Nervar chainrings is to measure the bolt circle.
Au revoir,
Fred Rednor - dans sa maison a Arlington, Virginia (USA)