I asked Yosepower a while ago about the AKM95 motors that they supply. They said their 95RS 350w freewheel motor is 230rpm with 4.4 gear ratio. Their 95RX 350w cassette motor is 240rpm with 8.15 gear ratio. The 95RX 250w cassette motor is 205 rpm with 8.15 ratio.
From that I concluded that RX denotes lower gears.
If you look on the Aikema website, they're all listed as 27/32km/hr, so I don't think that's it. For some motors, they make different windings and different internal gears for the same motors, depending on the size of the wheel that you want to put them in. I would have thought the RS and RX are more likely to be something to do with the construction than the performance parameters. Both versions have 40/18T two-stage reduction gears. Both have sideplates fixed with screws, so it might be the windings that are different. The only differences I can see is that the RS is heavier and gives less torque from whichever test they do., which contradicts with actual experience on hill-climbs. We know that the ones that Yose sell have different speeds, but that doesn't tie up with what's on the Aikema website, so it's all a bit of a mystery.
Yose are correct in what they're saying. members have tested them. the 250w one is definitely slower, but has more torque for normal hill-climbing, which ties up with more turns in the windings. Yose sell a 20" kit that looks like it has one of the same motors, but that will need a 328 rpm version and they say it's 250w. The problem is that we can't say that any other supplier doesn't have different versions of those motors that are wound for different speeds.
I think I stick with my original statement that Yose fix the speed of the 250w kits to 15.5 mph and leave the others unrestricted, and the RS version of the motor with maybe more copper in it is more suited to lower speed grinding.
