Tips & Guides Lubrication of Rear Hub Drive Motor – Important


Local time
8:39 PM
Nov 11, 2021
I live in Calgary and work internationally. At home in Calgary I have a Himiway Cruiser and at work I have a Trinx (popular in Asia brand) ebike. I went back to Calgary for 3 months. My Trinx was stored in a heated apartment with the battery out. It worked fine the last time I rode it. Last week I came back, charged up the battery and started to check it out. I had a few things I was going to do to it (new seat, rear view mirror, new rear brake light etc.). When I powered it up went to check how it ran, the rear wheel would not turn if I pushed the bike backwards. I could push the bike forward and also pedal it forward just fine. But if I tried to back the bike up, the rear wheel was locked up.

I brought it to the bike shop I bought it from. FYI, they are not a dedicated ebike bike shop. They sell about 90% standard drive bikes and 10% ebikes, so their knowledge about ebike electronics and electrical troubleshooting ebikes isn’t extensive. They recommended I bring it to another shop that deals exclusively with ebikes, electric wheelchairs, electric cargo dollys, just about any kind of smaller electric drive vehicle.

The tech guy there took apart the motor. He said it looks like the motor had been submerged in water or in a very high humidity environment. I rode in the rain a few times bit the bike was always stored inside, so it appeared to me that wasn’t really the cause.

See the attached. I’d say it appears the motor had been assembled with very little grease applied to the moving mechanical components, maybe even no grease at all. Then over the three months it was sitting in the apartment in +40C temperature for 1-2 months of that 3 months, whatever lube and other crap was inside the motor solidified up and stopped the motor from being able to run.

It's a Bafang motor so it’s a known and reputable brand motor.

I was expecting the worst from this experience but it turned out not so bad. The shop where it is now said they need to clean internals and gears, regrease everything and reassemble. The cost is going to be just the equivalent of $35.


Don't assume that just because something is new from the factory that it was 100% assembled perfectly in a quality controlled environment. Like I said, this is a Bafang motor, one of the most reputable brands.


  • WhatsApp Video 2023-01-12 at 14.55.09.mp4
    10.3 MB
People used to say i did un needed things when i bought kits....

I open them and make sure everything is lubed and sealed properly....better to be Sure than to have water ingress like old @ozzie21 motor there.
I've seen this happen with my own Bafang hub motors. Its a miserable experience cleaning all that rust out but its do-able. Here's how it usually happens:

All it takes is normal splashing from a ride in heavy rain. The cable ingress on a rear motor is directly thru the hollow axle ... and oftentimes there is zero waterproofing going down that channel and into the motor. Only a little water needs to work its way in, and in that environment that small amount spreads everywhere, and the not-stainless steel rusts like you see in that vid. Inside, the motor seems damp everywhere but on the ones I have had this happen to, there is no standing water inside.

Once you get the motor cleaned up, get some silicone sealant like you would use in the bathroom and inject it into that axle hole around the cable. Thats a permanent solution but make sure the motor has been open for a few days in a warm room and its TOTALLY dry, because you will be sealing moisture in if any is still there.
I got the bike back. It took less than 24 hours for the turn-around. The whole deal was just about $35 USD. The tech guy doing the work said he also had to re-shim the clearances between the motor and the drive gears because the motor was not properly assembled at the factory when first produced. It was nice dealing with someone who has some integrity and isn't trying to squeeze every cent out of you that they can.
Like I said earlier this is a Bafang motor. Bafang is one of, or possibly the biggest dog in the ebike powertrain drive world.
It's probably good that this happened the way it did because if I continued to ride it as it was I could have very well had a catastrophic failure of my motor which would have cost me a lot more than $35 USD. A new motor probably wold cost $400+/-, but I'm not sure.
Generally I avoid riding much in the rain. And the motor was never ever submerged in water. I did bring the Trinx to a car wash a couple of times but from owning motorcycles for over 40 years I never direct a high pressure spray wand anywhere there are such things as wheel bearings, steering head bearings etc., so that was not how this happened. I believe it was a combination of poor quality control on original assembly and also possibly poor design (bad seals or no seals where seals should be) permitting water to enter areas where it should not be was more likely.
I do all my own work at home on my Himiway, as well as all work on my three motorcycles. I also have an excellent BikeHand work stand and many ebike specific special tools, which I don't have at work. When I'm away at where I work I have only a small toolbox with basic simple tools so if this happened to be something complicated I didn't have the ability to do the work properly. But something like removing the rear wheel and servicing and greasing the motor and gear drive is something I can do going forward and if I need any special tools to do this, I'll get them but I don't think I'll need much more than I have now. I'll be checking this and re-greasing my motor at least before the beginning of every season.
I recommend that anyone with an ebike shouldn't neglect inspection and maintenance of their motor because the motor is the most critical and expensive component of your bike.
Anyway I've got it back and it's working right. So now while it's -25°C (-13°F) and chock full of snow outside I'll resume adding some doodads such as my Hafny bar end mirrors, a good wide Selle seat and a motion sensing combination rear light/brake light.
I've included a photo of the Trinx as it is now. The controller is turned sideways on the downtube because I bought an extra 52V x 20Ah battery and the 52v x 20Ah is slightly larger and interferes with the controller if I turn it straight ahead. The original battery was 48V x 13Ah so now if I think I might put a lot of kms on in a day I can use the larger battery or even bring both along with me. This bike is quite a bit lighter in weight than my Himiway and it's not a fat bike so I can get very good mileage from a battery. On my Himiway I'm running two batteries with a Fusion battery blender and I get an easy 200 kms.


  • Trinx January 2023.jpg
    Trinx January 2023.jpg
    159.3 KB · Views: 126