My everyday beater bike is a 1994 Specialized Hardrock that's pretty much stock.
The original crankset is 28-38-48.
The original cassette is 12-28 (7-speed Shimano HG)
The original rear derailleur (still installed) is Shimano Alivio.
I recently replaced the 12-28 with 12-32 (7-speed) SRAM cassette.
The capacity of the present-day Alivio rear derail is 34 teeth. I'm hoping it was the same back in '94 when this was new.
If upper pulley contacts gear wheel, tighten down on the "B" screw until proper gap.
My problem: I've tightened down all the way on the B screw and there's still contact/vibration/noise when I'm in the small chainring/largest gearring combination.
Interestingly, there is no such contact when I am in the middle or large chainring.
I installed a new chain when I installed the new cassette. I sized the chain according to Sheldonbrown; but the only thing I can think of is that the chain is too loose. When I am in the small cr/largest gr combo, if I pull on the chain (same affect as a shorter chain), the pulley separates from the gear ring. So it's obvious that the derail has the capacity for this 32-tooth gear ring. Could the spring (s) have lost their zing over the years?