Originally Posted by
rccardr
Mmmm…my memory may be failing me at age 72, but seems to me the wrap on a 6600 is 37 only on the long cage.
Pretty sure the short cage wrap is the same as the 640x- somewhere in the high 20’s.
Most of these originally came with a 53/39 (14) and maybe a 12/26 (14) = 28. Although I can testify that either will happily shift a 48/34 (14) and 12/30 (18) =32.
Thanks! (and to
Kontact too) If I accidentally looked up the wrap of the 6600 GS (not SS) that explains my confusion here. High 20s official would make more sense for both, as you say, given the typical setups.
My wife's bike has 42/28 double crank with 11-30 cassette (the Shimano "road" rear derailers of 8/9/10 era usually worked with 30t large cog in practice).
I'll go with a 9-speed-era 105 medium-cage model, which will have more than enough wrap for this setup, unless it doesn't handle the large cog in which case I'll use a medium cage mtb derailer.