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With respect to dating -

Verot's model nr. 80 does not appear in their catalogue of 1982 yet the model 99 is still there. So it seems reasonable to figure its launch was after that year. If you wished to employ a Verot product with the 86mm BCD it would seem more correct to go with one ot the 99 iterations.

Also a note of background information - for readers who like the 86mm BCD but also like the "olde tyme" look of the 50.4mm five-pin sets Verot began offering an adaptor chainwheel in 1977 which permits one to fit 86mm BCD chainwheels to five-pin sets.
It is part of a set called model "49Tn" and is part nr. 490T:



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