If you are using the same motor at 250W (which is capable of 500W), it makes sense to hide the controller inside the motor-shell to reduce wiring clutter. However, both the motor and controller generate heat. So if you find that on your particular commute generates enough heat that the internal heat protection shuts down your power, the best option is to use the 650W-rated or larger kit, which has a separate and external controller.
Since this style of system allows the motor to use the bikes gears, the 24V, 36V, and 48V versions are each wound with a different diameter of wire to change the motors Kv, which ends up with all three versions spinning at the same RPM.
http://endless-sphere.com/forums/viewto ... 8#p1024211
AFT and several other vendors make aluminum fins that can be attached to the outer shell of the motor to assist in heat-shedding when under heavy-duty use. I have included certain key pictures, but there are many more in the link.The "500 watt" motor has a Kv of approximately 125 rpm/v. As I recall the "350 watt" motor has a slightly higher Kv, maybe around 135 or 140.
phase 1: 68 mOhm
phase 2: 67 mOhm
phase 3: 67 mOhm
phase 1: 73 mOhm
phase 2: 71 mOhm
phase 3: 76 mOhm
Paco of Cyclone Taiwan told me once that the Cyclone motors are Wye wound
http://mrbill.homeip.net/albums/cyclone ... index.html
Here's the planetary reduction gear. It uses steel teeth, so it will be very long-lasting and can take higher power. However, it is very loud.
The driving sun gear has 9 teeth, each planet-gear has 33T, and the outer ring gear has 75T.The reduction ratio is 9.33:1
This is the stock 500W controller. At 24V, it should provide a maximum of 20A
This is a brushless, 3-phase, radial-flux, 12-pole / 8-magnet, inrunner. The two yellow wires near the top are for a temperature sensor.