E-Bike System

[Thomas]

I went with a 9C direct drive BL hub motor and 40 A controller from Grin Technologies in Canada (ebikes.ca). Their customer service has been great and the cycle analyst is very useful (low voltage limit, speed limit, Wh/km etc.).
Picture of the completed bike:
https://twitter.com/webetho/status/2.../photo/1/large

Attached is a picture of my torque arm, which is waterjet cut from 6 mm stainless steel, the slot milled to fit the axle and then mounted to the bike frame with an M4 screw. I have one on each side.

I was testing 18s lipo yesterday and reached 63 km/h with max power of 2.5 kW. My drive battery of made of 6s 5 Ah lipo packs. I'm using a seperate 2s A123 battery to power to bike's lights. To avoid sparks when connecting the battery, I split up the positive to an additional connector with a 250 Ohm precharge resistor.

Is it normal that the motor vibrates enough to make a loud noise and I can feel it on the saddle?