It's less of an issue for this device. The reason is that the motor is further from the axle than a hub motor would be. Thus, there's less force on the frame for a given amount of torque.

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mkl 2 hours ago | parent [-]

A lot of extra force when slowing down from faster speeds though, no matter where the motor is added.

	▲	happosai 2 hours ago \| parent [-]
		Not a lot of extra force. About 5% more weight you need to slow down (80kg rider + 10kg bike + 4kg motor + battery)