Originally Posted by
Ron Damon
I used to have a similar setup -- SRAM Dual Drive 3 with a 10-speed 11-36T cogset with a single chainring -- but it was simply too much gearing, 19-120 gear-inches or something crazy like that. I got rid of it because it was plainly excess gearing at the expense of weight and complexity. Your friend is even worse with a double crank and FD. Just because you can doesn't mean you should. There's a lot of aspirational, Walter-Mitty-esque gearing going around.
Btw, the Sram DD3 hub has a torque limit. You can't run a big cog and too small a chainring with it without busting it.
For me, I agree, I don't need a racer-high. Some folks do. What's more useless is just slicing the ratios into ever smaller steps.
DD3 torque limit: Now you got me curious. I can't find exact value online, just says avoid small chainrings. I wonder if applies to everything, or is more critical in low range, middle range (direct drive, so I think it's a dog-clutch that bypasses the gears), or high range? Digging deeper, AI references the torque limit for the cassette lockring, not a value for the hub. Just curiosity. The value is probably based on large wheels, so 20" wheels, providing the same ground thrust at lower hub torque, might be fine.
If I need a lower-low that a cassette won't solve, I've seen folks on here doing over 20T jump on 2X chainrings (since I can't fit a 3X on mine), between that and a bigger cassette, that would get me there, and kept simple.