I believe that the earlier rings for the 49 crankarms were model #13, and had 7mm non-counter-bored holes for mounting the inner ring and used a hex head bolt with a 7mm shoulder (rather than the later 10mm recessed hex-socket bolt). I have some of the later mode #490 Stronglight rings with the 50.4 and 122 BDC holes, and they have 10mm counter-bored 122 BCD holes and 7mm non-counter-bored 50.4 BCD holes. Don't know and won't speculate on other Stronglight iterations.
Wayne
-- Wayne Bingham Velo Classique PO Box 2069 Purcellville, VA 20134 USA 540-338-8376 http://www.veloclassique.com
Jerry Moos wrote: I guess I learn something every day. I thought the model 49D had 10 mm holes to attach the inner ring, and that the 10 mm bolts carried over to mods 57, 63 and 93. But evidently not. Can anyone confirm that early mod 49s had 7 mm bolts for the inner ring? I always wondered how, if at all, mod 57 and 63 rings were different from mod 93. It seems the mod 57 at least had smaller holes. What about mod 63?
Regards,
Inresponse to Ted Baer:
WTB/WTT: I am in need of one Stronglight 57 Super Competition Chainring.
Prefer size 52--but 51 or 50 would also be suitable. The BCD of this ring
is 122mm. Chainring bolt hole diameter is the early 7mm size. I am looking
for NOS or excellent condition.
Would prefer to pay you cash via PayPal or Money Order, but if you are in
need of a specific item, I may have it for trade.