Originally Posted by
Ron Damon
Assuming a 50-406 tire/wheel, this is how I myself would play it: 42T x 11-36T, 10-speed with a stubby Shimano Zee M640 RD. Yeah, I know the spec sheet says 34T max cog and 9-speed, but I'd push it to 10-speed, 36T.
42T x 0.75 = 32T, 42T x 1.33 = 56T
Note the substantial gearing overlap.
FWIW, the gearing on the SDD3 is
0.73, 1.00 and 1.36, only marginally wider than the SA.
A Schlumpf mountain drive is 0.4 and 1.0.
I've always wondered if combining it with an 11 speed 12-28 would be practical. No overlapping gears, 583%, no efficiency loss at 1.0, and very close gear spacing with 22 unique steps, between 6.3-12% steps.