Continuing a thread, Mark Bulgier wrote:
Gran Turismo and Rally both say the following: 13-36 -- 36-54 That looks suspiciously like a freewheel range followed by a chainring range, no? And the Gran Sport says "Da 14 a 26 Denti", clearly referring to the freewheel. <snip>
FWIW, here are other data points: Campagnolo Gran Sport (the one before the "steel" Record: "DA 14 A 26 Denti" Campagnolo Sport (single jockey pulley, sprung from hanger): "DA 16 A 22 Denti"
Mark wrote further: "Still seems illogical to give the minimum tooth size for the rear - what would keep them from shifting to a 12?"
I tried real hard in the Good Old Days to get the GS to cover a 13-21 block, with a close split up front. It always skipped on the 13. I attribute this to the major design difference between the GS and the early Record: The GS has pivot for the jockey pulley cage exactly centered between the pulley centers, so the upper pulley doesn't track too well. In contrast, the "steel" record has the pivot asymetric, offset in front of the line between the pulley centers, and offset toward the upper pulley. This lets the upper pulley get closer to the 13 th cog.
Your mileage may vary... harvey sachs mcLean VA
Oh well, these eccentricities are
part of the charm I guess.
Mark Bulgier
Seattle, Wa
USA