Rear hub motor grinding


New Member
United Kingdom
Private land use only
I wondered if anyone could help me .
I was going to build my own bike but due to work and my kids I didn't have time .

I bought a pstandard electric bike from a UK store .it was a ncm moscow plus . I was offered it cheaper than what it was worth as it had been a display and used.

I believe as uk limits to 15mph and 250 watt motor .

The bike is 48v with a 15 or 16 amp controller .
So I figured the peak performance of the motor is actually higher than 250 watt.

I have seen people , Buy a different display and have it derestricted up to 28 mph . A lot of these people aren't from eu so they have the 500 watt rated motor . But someone from the UK has it derestricted and his bike was from the UK and he's pretty sure he has the 250watt branded motor

I have tried this display and when I hit 20 mph the das kit rear hub motor Makes a terrible grinding noise and all motor assistance stops at 20. .

I was wondering . Is the the motor reaching its capabilities and cutting out ?

Or have I bought a bike with something wrong with the motor ?

I figured the peak performance of motor would actually be higher than 250 Watts considereting the voltage and ampage of controller . So I'm worrying it is a fault with the notor it's self?

Thanks in advance
Does it grind and make a racket if you rev up the motor with the wheel off the ground?
No its fine if I have bike upside down .throttle will take it to 18 mph. Im not sure of the speed when peddaling with wheel raised but there is No noise . Only when riding.
I have checked all wires and brakes gears, cassete etc in case it was something silly rubbing against something, it seems , what im hearing sounds like the motor as it stops giving assist .. when riding at 20mph.
I didn't think the motor would make a noise like that when it gets to its max rpm though.
Could the controller possibly have a speed limit compared to the u.s models ?
The motor works fine with no abnormal noise up to this speed though.


Does it grind and make a racket if you rev up the motor with the wheel off the ground?
I haven't taken the wheel off yet to inspect or taken pictures or video of the sound which doesn't help lol
This all started when you put on a new display?

The reason I asked if it made noises with the wheel off the ground was to find out if the load on the motor was making it grind. I have heard two of my bike motors make a growling sound as the speed went up while riding. They didn't do it for very long. About ten minutes later the motor didn't work at all and I was pedalling home w/o power. Bad controllers. Water got inside. The second time it happened, I knew what was going to happen.
OK I rode it again this morning and it doesn't sound like a grind anymore.. more like disc brake rubbing if that makes sense. But definitely isn't the disc or anything else ,because as soon as I pedal without the motor or stop using throttle its fine, if I was to pedal down hill without motor it wouldn't make the noise.
Do you reckon a 500 watt motor will give it that extra speed ?

I assume British motors and u.s versions of the same bike were the same but just branded differently . To get around the law.