Yesterday, I did an other trip to go to work : 23 km in the day. I was very often at top speed, and pedaled less than the first day for the hills. Conclusion : 11.3 Wh/km and 32.1 km/h average. I modified the sandow, and now the motor doesn't touches the tire in free wheel, nickel !
But when there are bumbs on the road, the motor rotates and comes to touch the tire.
adrian_sm wrote:As for tire wear it could be a few different things:
1) too high power. Your tire can only take so much torque before it shears the rubber apart
Maybe, I don't know : the max power is about 1 kW, during the hills.
adrian_sm wrote:2) initial contact angle of motor and tire. Needs to climb the motor and not slip on first contact. Simple test put the rear brake on, light hold the motor on the tire, then try to turn the motor. In one direction it will slip, the other should climb the tire. If it slips in both directions, then you need to have a more perpendicular contact angle.
I verified, and it is ok, the motor climbs and doesn't slip.
adrian_sm wrote:3) amount of tire/motor engagement. Not enough slips at high torque, too much and it distorts the tires across the motor causing additional tire wear.
I modified the stops : now the motor can engage more in the tire, and I have the impress that the tire is less wearing down than before. But I have to test it longer to see if it is really efficient. Riding for a total of 55 km, I have already lost the middle of the tire rubber thickness
adrian_sm wrote:4) drive angular alignment. The motor shaft may not be parallel to the tires rear hub, this will cause the motor to shear tire side ways. Have a close look at the rear tire as you engage the motor under power, and make sure it is not pulling the tire to the left or right, if it is rotate the drive on the seat tube and check again.
I will try it, but I need to use the camera, otherwise I can't see because of the frame of the bike.
adrian_sm wrote:5) acceleration rate of the motor. If it ramps up too quickly it can rip through the tire too.
Tha acceleration rate is slow, thanks to the Hobbycity ramp module. But there is inevitably slip when I am in freewheel and I start the motor : the tangential speed of the motor and the tangentail speed of the tire are not the same.
adrian_sm wrote:6) Tire pressure may have some impact, but I have done enough testing to understand it properly yet.
The tire pressure is 3 bars, do you think it is ok?
adrian_sm wrote:As for my interface, it is so close now. It will eliminate all the non-alignment issues mentioned above.
I don't undestand, why do you say it will eliminate the non-alignment issues. These non-alignment issues are due to "mechanical " problems, isn't it? How could you solve them with an electronic interface?