My first 10-speed was a gold-tone 1963 Schwinn Sierra (15-speed Continental) that I bought used for $15 in 1975 while in grad school in Ann Arbor. It had a bent (Ashtabula) crank, so I bought a 10-speed Continental crank, and overhauled the bike, installing new tires, new rings, new chain. Huret Allvit RD if I remember correctly (Huret anyway). I rode it with great pleasure until I bought a new R531 frameset and built myself a "racing" bike in 1985, with more exotic gear. I gave the Schwinn to a friend; haven't seen him in awhile, so I don't know if he still has it.