Motor P2-B 48volts ( Brushless/Geared) : $300aud  plus $70aud freight to any country

There are some differences in the structure of this motor compared to motor P2-A as it is used at a higher voltage and there is quite a bit more  power/torque available for hill climbing. It also means a few differences in the motor structure to acommodate this extra power. Also its a brushless motor so it runs at very high efficiency meaning more distance for a given battery capacity.

 I've decided to go with the version that has no freewheel mechanism. One reason being  this motor has a fairly low resistance even without a freewheel mechanism (it doesn't use helical gears but the straight type of gear cut - sorry I don't know the correct name for it). The other reason is that not having a freewheel mechanism means that its possible to use a regenerative breaking type controller with this motor.

 Also having a geared motor running at 48volts and 18amps maximum current means there is alot of torque produced and I believe that the freewheel mechanism will most likely be the first part to wear out, so not having it will extend the life of the motor (the manufacturer had also suggested this was the case that a freewheel mechanism may wear out prematurely with this motor). A geared motor is going to have a shorter lifespan than a non-geared motor simply because it has gears and gears do wear down over time. Depending on frequency and type of use I would expect this motor to last between 3 to 5 years before the gears would need replacement . They can be replaced!!! Life of the motor will also depend on how frequently the gears are greased, probably once every 3 to 6 months would be suitable depending on use. Also this motor is extremely easy to take apart, the whole motor and gear mechanism simply comes out as a unit once you take off the hub plate cover.
Also the bearings are very easy to get to if they ever need replacing.

This motor  comes with two nylon and one metal planetary gear similar to the P2-A motors. Nylon gears , I was surprised to find, are very  durable and are used in some other well known hub motors such as the (rather expensive!) Heinzmann motors from Germany. 

 The kit comes with a regenerative type controller. The regenerative controller is quite a bit of electrical engineering  There are other regenerative controllers available such as that made by 4QD (www.4qd.co.uk  in England but they are very expensive indeed and are now also available commonly in wheel chair scooters but still very expensive).
{postscript: I think 4qd controllers may be only for brushed motors}

Presently I can only sell the motor kit NOT laced into a rim, I'm hoping that some time I might be able to offer with already laced into a rim. But at the moment not enough time to organise getting motors laced into a rim, but should be able to do that at some stage in the future.

DIMENSIONS:

Notes on dimensions: As the motor comes it has a thread on the left and right sides and is designed for mounting into the rear of a bicycle.
Using as the motor comes requires a rear dropout width of 15cm (wider than most standard bikes which are about 13.5cm, its designed for chinese bikes). Solution pull out rear frame to suit. Other solutions: 
1. cut off the left hand thread you can get motor width down to 13cm, but will offset the centre-line of the wheel by about 1cm to the left so brake pads will need to be adjusted to suit. Requires extending flat part of axle with grinder.
2. for use in the front forks you can cut off both threads which will give a width of 11.5cm (probably too wide for most bikes which are 10.5 cm across the forks).  Requires extending flat part of axle with grinder.




Weight: 4.4kg

What's inside the P2b 48v planetary geared motor:

The outer casing:
Outer casing is some type of alloy which is quite lightweight.

 



The Motor:
The motor is 48volts brushless type. It has neo-dymium magnets on the inner rotor which make it quite efficient, probably around 80% efficiency.
Hall sensors are located on a circuit board at rear of the motor.

 


Drive gear: Drive gear ratio is 4:1
Outer ring : 48teeth  ,  planetary gear: 18 teeth , sun gear 12 teeth
The driving gear is a metal toothed gear which rotates at the same speed as the rotor and is joined at one end of the rotor.
 

The planetary gears are located on a cage which is at one end of the motor. There are two nylon planetary gears and metal gear, this seems to be a common method used for reducing noise whilst giving low wear of the gears. The outer ring gear fixes into one of the face plates of the motor casing and the planetary gears are effectively driving the outer case (and wheel) via this outer ring.

 

The axle of the motor is in two parts, one on each side of the motor.


Below Torque Graph for P2b motor  tested on 48volts: (graph supplied by a testing company not associated with the maker of the motor).

A few results from the graph below:
1. Because the motor is brushless the efficiency is very high and quite surprising to be this high considering its  a geared motor . The peak efficiency was  82% which is the same as achieved by gearless motors. This also  seems to verify the low friction caused by the gears and thus not really needing to have a freewheel mechanism which allows the motor to be used with a regenerative type controller.
2. Maximum power output is quite high at 490watts. Maximum input power is 780watts.
3. Max. rpm (no load) for 26" rim is 270rpm. 



Graph shows a maximum torque of 57Nm but the company didn't tell me which size rim the test machine was calibrated for , so I cant give any details on torque values for different size rims. It sounds like perhaps tests were calibrated for an 18" rim as 57Nm is quite a   high value. I guess I will just have to get some results from test rides and put those up to see how the motor performs, should be some up by November 2006.


What comes in the kit:
1. Motor
2. Spokes to suit rim size
3. 48v brushless controller ( 48v brushless controller with regenerative braking )
4. Throttle with led lights for battery voltage (twist or thumb type throttle)
5. Brake handles with controller cut off switches.

There are two different motors depending on which rim size you have. The motor above was for a 26" rim, a 20" rim has a higher rpm motor in it but the gear ratio remains the same at about 4:1.

Still to put up installation instructions and road test results.

beware of spray ebike company: more info

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