Q: The hub motor makes a noise once every turn and it gets stuck (or at least much more friction) at the same angle. It feels like it could be some magnetic effect but more likely it´s some mechanical contact that´s disturbing the rotation.

A: The noise comes from some metal impurity on the magnet.

Solve: Disconnect hub and remove it

Other answer 1.
Take rotor out of the magnet hub isn’t easy.Be careful your hands.Need two guys to do this.One guy press the hub,the other draws the rotor.

Other answer 2.
No other way to solve it,except disconnect hub motor.
Do it as the instruction.Be careful.

Other answer 3.
Magnet is easy to magnetize metal matter.Assembly hub motors should have a clean work environment.

Other answer 4.
There is no any room between rotor and magnet.See picture.Metal scrap may be inside the winding.Test motor before shipment,I think can’t find this problem.But after long distance to ship,it will be magnetized by magnet.

Other answer 5.
Small problem,it’s easy to repair.I disconnected two hub motors,one is old motor,the other is new one,and exchanged the rotor to different hub.That changed motor’s performance. Interesting job.I think you will like to repair it.

How to disconnect hub motor?
Disconnect it as below:

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New ULTRA powerful and efficient Gearless motor custom made with higher grade laminations, wider magnet stack, high speed NSK bearings, Honey well hall sensors, more copper fill, and all out higher performance. We went through all the stops to make this motor the absolute best hub motor on the market.

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Detail:
Size: 14″, 16″, 18″, 20″, 24″, 26″, 700c and 28″ hub motor wheel
Rim: 14″, 16″, 18″, 20″, 24″, 26″, 700c and 28″ double wall alloy
Spoke: 12 gauge × 36 pcs
Motor Type: brushless gearless dc motor with hall sensor
Voltage: 48V
Power: 1000W
Efficiency: 90.5%
Max speed: 731RPM
Mechanical brake: Disk or V
Cable location: shaft end , right
Cable length:100cm(front) — 150cm(rear)
Install: spacing of 100mm front — 135mm rear fork
Noise: < 60 db Surface: Black painted Net weight: 6.5Kg / 14.4 lbs Compare below performance data.You will find leaf newest motor saving 10% of electricity, improve the efficiency of 8% With The Newest Materials Steel Rotor. How to count speed as RPM? For example: 20 inch hub motor,max speed:731RPM * ONE cycle= 3.14 × 20inch × 2.54( 1 inch = 2.54 cm) = 159.5cm ÷ 100 = 1.6 m( 100 cm=1 m ) * 1.6 m × 730RPM = 1168 m ( ONE minute ) * 1168 × 60 = 70080 m =70 km ( 1000m = 70 km) * 70 ÷ 1.667 = 42 mph