I bought a 1500w motor & supposedly compatible controller from ebay. I put it together, and it worked good!

I let it sit a few weeks. Hub is now FROZEN. it has ~2" of free roll then hard stop. I CANNOT turn the wheel past this point.

  • I unplugged everything from the hub. It remains frozen.
  • The hub itself was outside but under a tarp during hurricane Ida. I set the controller up AFTER that. Worked good over a week of testing. It has seen a little rain since, but it lives in a carport.
  • A friend suggested that the motor might actually be a 1kW not a 1.5kW, and the controller toasted it? Seems iffy, because it was fine on the last ride.
  • With ~20 lbs of torque the wheel will not spin at all. I am hesitant to push harder.

I'm stuck! Do you got any ideas? Thanks!

There will be no technical support from the seller, it came from a Chinese seller via Ebay.

Are there any rust marks visible on the outside?
Yes - the spring-wire-protector-thingy at the axle shows some corrosion.

Can you roll the motor backward at all past the 2" window or is it a hard clonk at both limits?
Hard lock in both directions, but no resistance till it locks.

  • There are at least a half-dozen possible causes of this. Need to narrow it down. Oct 16, 2021 at 2:17
  • 4
    "I got a 1500w motor from ebay" -- there's your problem. Buying a 250w mid-drive motor from a reputable manufacturer like Bosch or Shimano would have been a better plan. (Except I understand that they are mainly sold in already assembled bikes and it isn't easy to find frames that accept these motors sold separately.)
    – juhist
    Oct 16, 2021 at 8:01
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    “i unplugged everything from the hub. It remains frozen.” This pretty much makes it a mechanical problem. Sometimes these motors have a built-in freewheel mechanism. It’s conceivable that the pawls or some other part got stuck (maybe because the grease went hard or bad). Is there any way to open it?
    – Michael
    Oct 16, 2021 at 8:28
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    @TrassVasston You can also take photos when you get stuck, and post a new question here or in Bicycles Chat. We'll try and help, but ebike motors internals are kind-of getting toward the electrics SE site's areas.
    – Criggie
    Oct 16, 2021 at 9:13
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    @juhist excellent point on the wattage. In some parts of the world, an ebike is limited by power. I could have up to 300W of assist, but if the motor is over that then legally it becomes an electric motorbike and needs registration, plates, rider needs a motorbike licence, WOF, etc.
    – Criggie
    Oct 16, 2021 at 9:15

1 Answer 1


If I had this bike, I'd contemplate selling it (or the kit) as a $1 no-reserve auction. It is going to be a continuous stream of problems, and you're heading for the sunk-cost fallacy.

In the short term, take the motor off the bike, and restore it to normal operation so you can still ride.

Your fixing option is to start with exploratory surgery into the motor, and see what you see. If you're really lucky you might find some documentation on the web to assist, otherwise you're going to have to take it apart one piece at a time.

Remember to take photos as you go, to help with the reassembly process. I started listing tools you might need, but it got very long and useless.

Based on the description, it is a 3 phase AC motor in the wheel's hub, with a separate controller at the handlebars and a separate battery on the frame or on a rear rack. There would be two DC power wires from battery to controller, and three power wires from controller to the motor, and possibly smaller sensor wires coming back the other way from motor to controller. There's a handlebar "dashboard" and possibly a throttle.

So you won't see much by putting a DC multimeter on the motor wires - its potentially a 90V AC wave at up to 400 Hz (many combinations have been used) DON'T GET HURT you could do yourself an injury if the system is energised.
So take the batteries out, hold the throttle open to completely discharge all capacitors. Extra safety, leave the whole bike unplugged overnight and work on it the next day.

The problem described suggests that "something" has moved into the wrong place and is blocking "something else" My first thought is a planetary gear has somehow moved and is blocking the ring/pinion gear from moving, or a bearing ball/needle has fallen into the wrong place.

It's also possible you've had a shaft fail and the debris is blocking something in the gearing.

A good hard shake of the motor in several orientations might be useful. You should not hear things rattling around inside - if you do, they have to come out.

So - if you're competent with your hands and with tools, then this could be a good project. However if you're not confident with tools, perhaps let this motor-kit go and consider buying something better next time.

  • 1
    We've decided to see about returning it, and if their policy so allows, we will keep the motor and attempt to fix it then. I am marking this as the answer, as it is in line with the top comments from other forums. Oct 18, 2021 at 22:27

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