[remy_martian]

The two wheels can't be turning at different speeds unless one is slipping.

On a street motorcycle, if the front wheel is slipping you are in deep doodoo.

One or both are slipping and if traction is regained, the rider gets to taunt death with "high siding" off the bike (think of the bike as a catapult).

So, no, you don't average speeds...you pick one.

On motorcycles, OEMs use the front (not the rear as suggested) wheel for the speedometer.

As an aside, I'm curious about the make and model of hub motors you're using, and the power rating of each.

I suspect you have an electric bicycle you've overpowered legally to fall into motorcycle regulations, but it's not a motorcycle per se.

 

[remy_martian]

^ Maybe you should reread - rotational rate is not rotational speed. You can't change the context of your post, or mine. I was answering OP, not you.

Speed is distance over time. Rotational rate is either radians, or revolutions, per unit time. Tires are rated at max speed, not RPM....one of the main reasons for speed limiters on production vehicles.

We're also talking about motorcycles, not cars, in this topic. The treatise on different rotational SPEED of the front/rear wheel are irrelevant. Averaging the two, as proposed, is unnecessary, given the mice-nuts difference (zero if no slip)...let alone your going around corners, lol.

One tire, of known circumference, and its rotational rate can be used to derive a speedometer. In a motorcycle, every one I've seen is off the front wheel - whether electronic or mechanical.