[Duncan]

Hi Ripperton
My tuppence worth
The motor is very close to the pivot point so the effect of it's mass on the suspension is minimised

Also because the motor is on the swing arm throttle/suspension effects are minimised - both the effects of the motor torque on the suspension and the effects of bumps on wheel torque

Overall I would think it would be pretty good

 

[Duncan]

Hi Rip
Re the torque reaction - yes you will get a torque reaction with the motor on the swingarm
BUT you will also get a torque reaction with the motor on the frame

That bike looks as if the rear swing arm is about half the length of the whole bike - tire contact point to tire contact point

So with the motor on the swing arm you will get about twice the effect of having it on the motor
As the effect is reversed you will get about the same amount of movement - but in the opposite sense!

So basically much the same movement

The advantage is that wheel movement (from bumps) will not put any torque into the drivetrain

 

[Duncan]

The motor torque will not transfer to the frame except from the wheel which Is always the case no matter where the motor is mounted. Having it on the swing arm eliminates need for chain tension issues. If the motor is mounted too far out on swing arm it can cause issues with too much mass on the end of the fulcrum especially when off roading which is a common problem with hub motors. But by the looks of it I see no relation, as long as you are OK with your motor swinging up and down with your tire and not your frame

Nope the motor torque is ALWAYS reacted out through the frame ALWAYS - Physics 101

 

[Duncan]

The wheel torque is reacted to by the frame through the swingarm. Physics 101.

The motor is invisible to the frame if it's centered on the swingarm pivot. All forces are purely between the motor and wheel and the reaction to the motor torque is by the swingarm lever acting on the axle pin. Not the swingarm pivot. The torque of the motor is translated to the wheel. You coupd argue that the motor is pulling on the chain which lifts the frame at the swingarm pivot, but that is defined as wheel torque.

So, he was correct.

No he was wrong the torque is reacted to the FRAME through the pin and pivot

 

[Duncan]

...by the WHEEL

To the frame - AND to the wheel - as Newton said opposite and equal

 

[Duncan]

Almost equal.

Newton didn't burn rubber obviously 😂

Nope all wrong - just think about it - with the motor at the pivot point and the wheel locked I energise the motor - what happens? the motor torque causes the swinging arm to MOVE

If the wheel is not locked you get the same effect -