Electric scooter makes noise when accelerating

Hi everyone! Hope you can help me out with a problem with my ST2.

I bought it back in 2017, and it has been working fine until this summer. Now, I have a reocurring problem which seems to be happening when the engine is starting to work harder, from light performance up to moderate and high - uphill, accelerating, high speeds...

• it starts with a noise, from back wheel, sounds as if something was stuck between wheel and fender.

• The power from the engine is at the same time reduced, as if I was braking lightly.

• The noise disappears the moment I stop pedalling, even if the bike is still rolling.

• If I continue pedalling lightly then the engine still helps me without the noise, but as soon as I'm tempted to increase speed/power, this noise and light braking effect returns.

Does anyone have an idea what the problem could be? Suggestions for what I can try to fix this?

Few possible scenarios:

1. There might be something between the fender and the tire.
2. Rack or some other part touching the tire
3. Something to do with the crank or the rear axle. Make sure the rear axle is seated correctly.

Hi, thanks for answering me!

1 or 2 is not the case, since the noise is not present when pedalling lightly, or just rolling.

3: I also doubt it has anything to do with this, since the problem seems to be so connected to situations where the engine is expected to power the bike away with full speed...

I have also checked the rear axle, which seems to be as it should be.

Feels like the bike tries to prevent the engine from accelerating...

Hi, thanks for answering me!

1 or 2 is not the case, since the noise is not present when pedalling lightly, or just rolling.

3: I also doubt it has anything to do with this, since the problem seems to be so connected to situations where the engine is expected to power the bike away with full speed...

I have also checked the rear axle, which seems to be as it should be.

Feels like the bike tries to prevent the engine from accelerating...

Have you accidentally turned on regen?

Take a video of the noise, one of us might be able to recognize what it is.

I'll see if I am able to take a video of this and share it, thx for advice.
Not regen btw

A very similar problem for me. ST-2. During my ride yesterday the bike/motor started stuttering on acceleration. Debug attempted so far:
1. System reboot via battery removal
2. Settings reset to factory via menu
3. Removed and reset rear wheel In case of bad connection.
4.Since the stutter also happens on brake regen, I played with settings to set Braking Level to zero. This eliminated stutter from motor on braking.
5. It seems like the stutter happens just on acceleration, so I played with the torque sensor settings. Even if I change to zero the problem persists.

Any help would be appreciated. The shop I purchased the bike from here in Dallas went out of business. It’s not clear how in the world I can get this serviced.

Found this thread that seems relevant.

ST2 Motor "Judder"

So I got my ST2 last Friday. I have 105 miles on it so far, and until today was thrilled beyond belief with everything about it. On a ride this afternoon I came to a short, steep hill. I downshifted. I was going about 10 MPH and the bike began vibrating. There was a distinct loss of power...

A very similar problem for me. ST-2. During my ride yesterday the bike/motor started stuttering on acceleration. Debug attempted so far:
1. System reboot via battery removal
2. Settings reset to factory via menu
3. Removed and reset rear wheel In case of bad connection.
4.Since the stutter also happens on brake regen, I played with settings to set Braking Level to zero. This eliminated stutter from motor on braking.
5. It seems like the stutter happens just on acceleration, so I played with the torque sensor settings. Even if I change to zero the problem persists.

Any help would be appreciated. The shop I purchased the bike from here in Dallas went out of business. It’s not clear how in the world I can get this serviced.

Update: With help from Small Planet e-bikes in Longmont, CO I was able to diagnose a controller failure. They gave me a good deal on a replacement controller that was pretty easy to install for someone with experience and the right size Allen sockets/wrenches. First full ride after fix today and everything works flawlessly. Mostly rode level 1 to get exercise but 2 and 3 when needed. 5 year old bike with over 4K miles and I only used 30% battery to travel 28 miles. This is a rock solid bike that’s a blast to ride!

Is the sound you’re referring to a Loud vibrating that turns into a louder whine when peddling harder? I’m experiencing That sound when either applying more and more force to the pedals to accelerate, and also when braking as well.
The shop put a new controller and cable in when testing the problem, as well as tested it with a new motor (from another bike), and it worked fine with all my original parts put back in.
But it started again the day after.
Used to be intermittent, but happening constantly now. Hesitant to take it back without any ideas on what to assess at $80/hour labor...while also bearing in mind that they said it may be the motor that needs replacing, which seems like it'd cost at least four digits. :s
4,781 miles on it.
cant seem to upload a video of it as a comment.

The power cable to the motor has been known to cause vibration on acceleration