Rear Wheel Vibration

cansat

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Joined
May 11, 2022
Messages
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Hi Folks,

Long time luker of this website - I finally ended up getting an ebike kit about a month back. I bought a 29" 350w Green Pedel kit from a local(ish) supplier. So far, I have been absolutely loving it! Coming from a Jetson Bolt Pro, its been an absolute treat!

However, today I noticed that the bike had a bit of an unusual vibration. It seems to be coming from the rear of the bike, most noticeable when just rolling it across my apartment (as the floors are nice and flush). I cant figure out what the heck is causing it. So far ive done the following:
- Checked the brakes - they are fine, no rubbing
- Nothing it rubbing or hitting the tire
- Chain seems fine, vibration happens when the chain is not moving
- Tried rolling back and forth with motor off, on, and on in 'walk' mode - vibration always present
- Checked tire for flat spots, rim bulges, cracks - nothing out of the ordinary
- deflated and inflated the tire/reseated the tube
- spokes are all tight

Its really throwing me for a loop. No noise is present, just the vibration. I am thinking that maybe its something inside the actual motor, but I am not technical enough to diagnose something like that.

I appreciate any insight!
 
Are the tires knobby types? Or smooth tread?

Does the bike still operate normally?

If so, does the vibration happen more when you manually spin the wheel forward or when you do it backward?

Does the vibration feel "faster" the faster the wheel is spun?


If the bike does not operate normally, perhaps the phase wires for the motor (if it's a DD hubmotor) are damaged and shorting together, or FETs have failed (shorted) inside the controller.

Disconnect the motor from the controller, and retest; if vibration is gone the probelm is on the controller side of the connector. If still present it's on the motor side of it.
 
amberwolf said:
Are the tires knobby types? Or smooth tread?

Does the bike still operate normally?

If so, does the vibration happen more when you manually spin the wheel forward or when you do it backward?

Does the vibration feel "faster" the faster the wheel is spun?


If the bike does not operate normally, perhaps the phase wires for the motor (if it's a DD hubmotor) are damaged and shorting together, or FETs have failed (shorted) inside the controller.

Disconnect the motor from the controller, and retest; if vibration is gone the probelm is on the controller side of the connector. If still present it's on the motor side of it.

Hi there,

The tires are knobby (Michelin Country R).

The bike works fine and most of the vibrations are at low speeds. If I move the bike a bit faster it does vibrate a bit more.

When going backwards it's at its worst.

If I flip the bike upside down, it doesn't vibrate.

I did disconnect the motor and battery yesterday and the same thing persisted.
 
cansat said:
The tires are knobby (Michelin Country R).

The bike works fine and most of the vibrations are at low speeds. If I move the bike a bit faster it does vibrate a bit more.

When going backwards it's at its worst.

If I flip the bike upside down, it doesn't vibrate.

I did disconnect the motor and battery yesterday and the same thing persisted.

The two bolded statements make it sound like it's the tires, since if you have knobby tires rolling on the ground they do make some "vibration", and it will make more of that the faster it rolls. You don't usually feel this when riding on it, but when just rolling it along beside you, you might.

If the problem only happens when the tires are in contact with a surface and rolling on it, then that is a possibility.


If it is worse going backwards than forwards, and it's not the tires, then if it is a geared hubmotor, you may be feeling the gears inside the motor running (they'll be pushed backwards against the motor's magnetic resistance when rolling the wheel backwards, but not when rolling the wheel by hand forwards, so you'd get this only on a backwards rotation).

But you shouldn't feel any of the gearing rolling forward without motor power (you could with it running); ther'es a "clutch" or "freewheel" inside that disconnects the gears from the wheel in a geared hubmotor, when rolling forward (but not backwards).
 
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