Lesser gear count SA put the direct 1:1 in the middle,
so the reduction gear is in the hub
chainring /cog look not so curious ..

actually the inverse of the overdrive gear. 3/4 & 4/3, for AW3.
Recent S3X is the middle and 2 low gears of the 5 speed.

torque limits are recommended on the low side, not on the higher end,
sticking a huge chainring on and trying to go fast against the wind on the flats,
is just not that hard on the internals, though it may fatigue you.


I have an AW3 hub in my Brompton, folding bike, I got a Schlumpf Mountain
drive 2 speed planetary gear crankset, a 2.5 reduction gear..
a 50t chainring acts like a 20t in low, as the crankarms
turn faster than the chainring then,
and the lowest gear in the hub becomes 4th,
3rd is high gear in the hub, low range in the crank.

A Rohloff hub in a similar manner, uses its 7 speed planetaria
twice, 7 is high in low range, 8 is low in direct gear/high range,
#11 is the 1:1 gear of the chainring/cog/wheel diameter.

so they limit to 2,4 , a 16/38 in a 26" wheel is an excellent gear range
for normal hilly riding ..

Though, in a tandem they use a 16/42 as the minimum.