Hillhater said:
Which ever way you cut it, a 250w dd hub motor will not haul you up a 10 -15% hill !
That's not what was suggested. But it is a myth that a "drive through the bike gears" system is cost efficient or superior in terms of energy efficiency. When a low torque $200 hub motor (whether DD like the 9c or geared like the small Bafang or Cute) does not suffice, it is often wiser to plunk $3-400 into BMC (for most cases) or $400 into RC/leftside drive (for really steep hills/demanding use) than a mechanically complex drive-though-the-bike-gears. These incur inefficiencies by first gearing down the motor to pedal speed, then gearing up again, and these inefficiencies are always there, not just at peak load like the electrical inefficiency of a single gear motor at high loads. An electrical motor does not need 27 or even 8 gears. One is usually enough and two would practically always suffice.
The way manufacturers view this is that a simple low power hub motor satisfies likely 90% of people's eBike needs, (just like a small car is enough to take you to work), a higher power hub motor is likely good enough for another 9%, and the remaining 1% isn't really of interest for volume manufacturers.
That's why 9C is sold by multiple vendors here and worldwide.
BMC by a few in smaller volumes
Stokemonkey is a niche product
Cyclone likely has decent sales, but still a drop in the sea compared to all hub motors.
That is not to say that gearing is not good. A 2 stage 2 speed planetary that would match e.g. Astro motors would be nice. Could have a 5:1 first stage and an dis-engagable 2:1 or 3:1 second stage, then a chain or belt drive to a rear wheel sprocket separate from the pedaling gears. Such a setup would be much more complex and expensive than say a BMC hub motor though. One also has to think about the tradeoffs: Does the addition of cost and weight for the hear stacks make sense, when one could instead just put that money in a bigger motor. (a 2:1 selectable downgear might be 1" wide or more and weigh 1lbs. That weight and size could instead be used to double the width of the motor stator and rotor, which also gains exactly a factor 2 in torque, and additionally gains a factor 2 in power.