I have a few somewhat earlier 49D chainrings which were bored with 7mm. holes for connecting the rings at the 122mm bolt circle with hex head bolts. Later, the rings were bored 10mm and rings were connected with more modern (like Campagnolo) hollow nuts which tightened with an allen wrench. Apart from this, the chainrings are essentially identical - the outer rings all having the same familiar star pattern.
I know that the Model 63 "Super Competition" cranks (c.1963) were Stronglight's first to use the new-style fittings. However, I suspect it was quite some time before the company eventually would have exhausted their old stock and/or would have decided to re-tool for the newer type mod.49 chainrings.
Does anyone know exactly what year the change in bolts had finally trickled down to the mod.49 chainrings?
Thanks!
Bob Hanson, Albuquerque, New Mexico, USA