Hub motor bounce

I was wondering what would cause a rear hub to bounce? I put my bike upside down and hit the throttle and the entire bike shakes. Looking from above, the wheel seems pretty true, but I'm assuming it's not? Is that likely the problem?

You've got a serious problem if it's not the tire or rim.

It's usually the tire or rim!

Dumsterdave said:

I put my bike upside down and hit the throttle and the entire bike shakes. Looking from above, the wheel seems pretty true, but I'm assuming it's not? Is that likely the problem?

Click to expand...

Wheel is unbalanced. That can be caused by a lot of problems, including poor lacing.

Usually the reflector.
I use 0 reflectors or 2. 2 reflectors, properly positioned can balance any bicycle wheel.
Sometimes "Slime" filled tube (or fix a flat) will cause a nasty imbalance?

Dumsterdave said:

I was wondering what would cause a rear hub to bounce? I put my bike upside down and hit the throttle and the entire bike shakes. Looking from above, the wheel seems pretty true, but I'm assuming it's not? Is that likely the problem?

Click to expand...

I am pretty sure that your wheel needs to be balanced, tensioning the nipples correct to resolve your issue.

You probably need a bicycle shop do that for you to do it professionally.
Check this video: https://youtu.be/Jw25tqAcn_4?t=342

Your wheel doesn’t only need to be straight, it also need to be round. :wink:

Run at very low throttle to test for roundness.
Any up-down fluctuations?

If only up\down movement at high rpm then problem is weight-balance.
Remove reflector if present >> test again.

While bouncing, put chalk near tread to mark while "bouncing". Place reflector exactly opposite, test again.

Fine tune with 2 reflectors. Place opposite the chalk mark, equidistant, near opposite end for bad imbalance, back towards center line for slight imbalance.