Summary: a central motor, inside the wheel, fixed to the frame. the wheel goes around the outside, but can also move up and down for suspension purposes. how best to transfer the drive?
I'm brainstorming how to make an electric motorbike, making as much use of the available space as possible to allow for as many batteries to be fitted as possible.
Batteries aren't relevant right now; my focus is on the final drive at the back of the bike.
To maximise space, I want to fit the motor inside the rear wheel - this seemed the sensible place for it, it's already round and it's where the drive needs to go. it also means one less chain / transmission to worry about, and can help make the overall look of the bike a lot cleaner.
That may not be a big deal for all users. Lots of us like to ride slowly. In developed areas, the bumps at curb cuts and sidewalk seams are an annoyance.And maybe the main issue would be the increased wheel weight and MOI, as opposed to unsprung weight. Accelerating that puppy is going to take some extra work!
Obvious issue with this design is the penalty in unsprung weight, it would seem...?
As for the unsprung weight it's quite the opposite, it's at its minimal value (the rim and tire).And maybe the main issue would be the increased wheel weight and MOI, as opposed to unsprung weight. Accelerating that puppy is going to take some extra work!
Now that's an interesting point. If they cycle and dissipate heat constantly, then it becomes more like an exercise bike.Also, the suspension components are cycling constantly due to vehicle weight, even when rolling on a flat surface. Sounds like a lot of extra wear and tear.
I think that it does change caster. When the suspension compresses, the effective radius of the wheel is reduced (assuming compression due to a bump at 6:00). The center of rotation (hub) and the center of curvature (wheel) aren't the same (until the suspension recovers).As for the unsprung weight it's quite the opposite, it's at its minimal value (the rim and tire).
But I didn't think about the MOI and that is certainly a negative factor.
What I find also interesting is that the suspension geometry affects only the vertical motion, which is what it is supposed to do (no toe, camber, caster change or tire scrub as it moves up & down). But it might also become problematic to handle lateral forces in extreme cases.