GrasB said:
Could be done with a double at the front but difficult due to 1:1 being the lowest ratio.
true but that starts to defeat the simplicity aspect of a hub gear. It really does depend on how low you want the range to go. As the gear steps are in %ages it can tend to bunch too many similar gears together at the bottom of a range. In this respect SA had a reasonable idea but could have done with another big step, or two, at the bottom, currently it goes:-
28% then 5 at 13% then a final jump at 28% again - so you could have a range of 34 to 103 inches but the middle six would be 43 to 80. I'm not sure how the planetary gears work in the SA but a better spread would be given by 28% twice at the bottom and then climbing in 15% increments after that.
This is where I find the Rohloff disappointing, it's 14 equally spaced gears. the most useable setups seem to end up with too many close gears at the bottom. If you avoid this then you end up with too high a low and a top that's silly big.
I'm looking forward to seeing how the Shimano Alfine 11 speed stacks up, it should have a coup,e of graded %age steps to avoid the Rohloff style bunching, as does the current I-9. It has 11 gears covering 409%, compared to Rohloff 14 over 526%, SRAM I-9 9 over 340% and the 8 speed offerings over approx 305%.