MXUS XF15F hub

gcincanton

Just Joined
Oct 22, 2023
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My wife has a Magnum ui5 ebike with a failing Bafang 36V 350W rear hub motor. (BFSWX02). Will a MXUS XF15F rear hub motor (also 36V 350W) fit her bike? Is it a reasonably reliable motor or should I buy a complete replacement wheel with hub from Magnum for more than double the price of the Bafang motor? TIA
 

saneagle

Esteemed Pedelecer
Oct 10, 2010
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My wife has a Magnum ui5 ebike with a failing Bafang 36V 350W rear hub motor. (BFSWX02). Will a MXUS XF15F rear hub motor (also 36V 350W) fit her bike? Is it a reasonably reliable motor or should I buy a complete replacement wheel with hub from Magnum for more than double the price of the Bafang motor? TIA
You can fit any motor you want, but you have to change the spokes.

How's your Bafang motor failing? They normally work or not. Anything else is easier to fix than replace the motor.
 

gcincanton

Just Joined
Oct 22, 2023
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I'm not proficient in electric bike repair The motor "whines" quite loudly when spinning, both with the motor engaged or not engaged. The "volume" of the whine doesn't change much with changing rps, but the pitch of it does. I have a video of it, but apparently cannot upload videos here, just photos.
 

saneagle

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Oct 10, 2010
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There isn't much in the motor that can make a whine - only the bearings, and they're pretty easy to replace.

Are you sure that the mudguard or something like that isn't causing it? the last whine we had was a screw in the newly fitted rack was too long. Also the brake disc can whine if the brake isn't adjusted properly. If you have a disc brake, take the caliper off and see if the whine goes.

How did the whine start? Did it just invent itself one day or did it start very very quiet and get loader over a long time? Or did you buy a whiming bike? Spill the beanz.
 

gcincanton

Just Joined
Oct 22, 2023
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There isn't much in the motor that can make a whine - only the bearings, and they're pretty easy to replace.

Are you sure that the mudguard or something like that isn't causing it? the last whine we had was a screw in the newly fitted rack was too long. Also the brake disc can whine if the brake isn't adjusted properly. If you have a disc brake, take the caliper off and see if the whine goes.

How did the whine start? Did it just invent itself one day or did it start very very quiet and get loader over a long time? Or did you buy a whiming bike? Spill the beanz.

- Not mudgard / fender
- Not disc brake ( I pulled the caliper and tested, same whine continued)
- Whine began while we were on a tour of national parks earlier this month. It does seam to be getting progressivly worse.
- Sorry for my lack of knowledge on the subject: when you say it could be the "bearings", is that the same as the nylon gears? I'm planning on taking the hub apart today to see if I can identify whether the nylon planitary gears are worn / damaged.
 

saneagle

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Oct 10, 2010
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- Not mudgard / fender
- Not disc brake ( I pulled the caliper and tested, same whine continued)
- Whine began while we were on a tour of national parks earlier this month. It does seam to be getting progressivly worse.
- Sorry for my lack of knowledge on the subject: when you say it could be the "bearings", is that the same as the nylon gears? I'm planning on taking the hub apart today to see if I can identify whether the nylon planitary gears are worn / damaged.
Bearings are between the motor case and the axle. You can feel whether the bearings are OK if you take the chain and disc caliper off, then turm the motor.

Anothe cause is when people take the wheel off and put the washers and other axle stuff back on the wrong positions. Did it start after you fixed a puncture?

Nylon gears don't normally wine. They should last for 30,000 miles unless you did something to damage the motor, like jumped or hit a massive object. Even then, the damage would be localised, so it would make a repetitive npise as the wheel rotated.
 

Giocast

Finding my (electric) wheels
Sep 14, 2020
15
0
This thread is of great interest to me as just developed an intermittent vibration/whine that is not easy to find. If the wheel is allowed to spin with no load then it disappears. I have two Oxygen bikes with Bafang bfswx02 rear hub drives (250W/36V) and they have been faultless for 3K plus miles until now. Most common first mechanical fail is one or more of the permanent magnets deciding to walk around a little and then becoming dislodged enough to start making contact with the "armature". You can't miss the sound it makes and it's easy to confirm once stripped because of the witness marks. Providing no water has got in, all the bearings are more than man enough for the job on the 250W motor and i could detect no play or wear in any of mine, ditto for the nylon planet gears providing they have not become totally dry of grease. I can see no reason why I shouldn't add another 3K plus miles to the one i stripped after inspecting everything, but this has made the mystery even harder to solve due to no sign of anything wrong mechanically. If anyone picks this post up with any experience of similar, then would be very grateful to hear. I might try swapping the controller just to rule it out, but can't think how anything electrical could create this audible problem, maybe the Hall sensors shorting out/arguing with each other? - they do look really vulnerable when you strip the motor casing but mine were undamaged.
 

Sturmey

Esteemed Pedelecer
Jan 26, 2018
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Hi. I have a mxus xf15R (rear freewheel) and they are a little noisy I think by design. They use a 5:1 straight cut planetary gears which I think are by design noisy compared to helical gears. Other than that, its a good motor. There are other complaints on line about this if you google 'mxus xf15 noisy' e.g. below. But of course, there could also be an electrical problem in your case making matters worst. (e.g. poor phase connection will cause the motor to go out of balance/noisy)
PS One of my bike has steel mudguards that resonate every now and again when the motor is under load at a certain pitch and are noisy. I also had a spoke nipple that came loose lately and fell into the wheel cavity, making a lot of noise.
 
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saneagle

Esteemed Pedelecer
Oct 10, 2010
4,407
2,165
Telford
This thread is of great interest to me as just developed an intermittent vibration/whine that is not easy to find. If the wheel is allowed to spin with no load then it disappears. I have two Oxygen bikes with Bafang bfswx02 rear hub drives (250W/36V) and they have been faultless for 3K plus miles until now. Most common first mechanical fail is one or more of the permanent magnets deciding to walk around a little and then becoming dislodged enough to start making contact with the "armature". You can't miss the sound it makes and it's easy to confirm once stripped because of the witness marks. Providing no water has got in, all the bearings are more than man enough for the job on the 250W motor and i could detect no play or wear in any of mine, ditto for the nylon planet gears providing they have not become totally dry of grease. I can see no reason why I shouldn't add another 3K plus miles to the one i stripped after inspecting everything, but this has made the mystery even harder to solve due to no sign of anything wrong mechanically. If anyone picks this post up with any experience of similar, then would be very grateful to hear. I might try swapping the controller just to rule it out, but can't think how anything electrical could create this audible problem, maybe the Hall sensors shorting out/arguing with each other? - they do look really vulnerable when you strip the motor casing but mine were undamaged.
It's probably commutation pulses. Did you increase the power from when it was quieter?Get yourself a KT sine wave controller and the noise will go away.
 

Giocast

Finding my (electric) wheels
Sep 14, 2020
15
0
Hi. I have a mxus xf15R (rear freewheel) and they are a little noisy I think by design. They use a 5:1 straight cut planetary gears which I think are by design noisy compared to helical gears. Other than that, its a good motor. There are other complaints on line about this if you google 'mxus xf15 noisy' e.g. below. But of course, there could also be an electrical problem in your case making matters worst. (e.g. poor phase connection will cause the motor to go out of balance/noisy)
PS One of my bike has steel mudguards that resonate every now and again when the motor is under load at a certain pitch and are noisy. I also had a spoke nipple that came loose lately and fell into the wheel cavity, making a lot of noise.
After 4000 miles covered i had hoped you might credit me with the ability to recognise a serious motor noise by now Sturmey ;) This is nothing easy or obvious hence me posting - I was hoping someone might have had an identical experience and be able to shed some light but I realised that it would be a long shot.
 

Giocast

Finding my (electric) wheels
Sep 14, 2020
15
0
It's probably commutation pulses. Did you increase the power from when it was quieter?Get yourself a KT sine wave controller and the noise will go away.
This is the only sort of thing that makes any sense now, i noticed one of the longer of the 9 connector pins to the motor was dark and dull rather than bright brass yellow like the others but it's clean now. No, I haven't changed anything from std. As said, it is intermittent, i think i will check all connector blocks next.
 

Giocast

Finding my (electric) wheels
Sep 14, 2020
15
0
Just a quick note - after the first "glitch" on short test run, it didn't re-occur and bike was fine (and much faster) for 14 miles. It looks as though a clean and re-grease of planet gears has paid dividends. Has to be electrical problem now I feel sure, but gone for now, Thanks for posting replies.