250 watt motor and 18max current controller?

[RunForTheHills]

Torque arms are recommended. Grin torque arms are the gold standard. This is the torque arm they sell for the Bafang G311 motor that you have: https://ebikes.ca/shop/electric-bicycle-parts/torque-arms/torqarm-311.html

 

[harryS]

Self learning usually works. If you have a voltmeter, measure the throttle voltage to make sure it's increasing smoothly from about .70 v to a max around 4.3 V when you rotate it. Maybe it's jumping from 0 to 4V.

 

[PCeBiker]

Lithium grease for example right?

There's better grease to use.
I bought Corn Head grease, and Mobile 28 before I found out that Mobile SHC100 was better.

I used the Mobile 28.

Re-greasing the Ultra motor...is it time?

The Ultra motor is my UC Pro is getting louder and louder, so I think it may be time to re-grease the gears. This is the first time I've done this, so any tips would be appreciated. I've watched a handful of videos on this topic, using Corn Head grease, and it looks to be a straightforward...

forums.electricbikereview.com

 

[PCeBiker]

See vid.

You may have actually had your phase wires correct and the controller knew that the wheel was over revving so it kept shutting down the power?

That's just a guess, but try revving up your wheel slowly and see if it pulses.

The wheel spinning in the air behaves differently than a wheel under load.

The controller may be trying to protect the motor?

 

[PCeBiker]

,.. Do you think it will do the job. I ordered the one called 10x14x5: https://www.aliexpress.com/item/100...o.order_list.order_list_main.5.21ef1802dBjObF

I bought two of these that I didn't end up using.
They've got a better design than your link, but the Grin version is only a few dollars more, and worth the extra money.


I just found this on AliExpress:
C$16.58 | M12/M14/M16 Electric Bike Torque Arm Accessory for Front Rear E-bike 250W-8000W Motor Ebike Torque Washers Motor Safety Parts

https://a.aliexpress.com/_m0tdKNB

 

[Electricmover]

Torque arms are recommended. Grin torque arms are the gold standard. This is the torque arm they sell for the Bafang G311 motor that you have: https://ebikes.ca/shop/electric-bicycle-parts/torque-arms/torqarm-311.html

Hmm not sure if it would work since the axle on this weid motor is basically round and 10mm. M10 I think(?).

ow's Video - Jan 2, 2026

www.veed.io

Look how the screw there is basically round from the pic below. Also do you know if grin has a European office or ship to Europe, or inside the EU, without the extra fees? That was often the problem a few years back when I was building a lot. The shipping cost was always high from american stores/companies. Now, we do have Amazon here so if it can be bought through Amazon it usually works well and has ok price.

 

[PCeBiker]

Your motor is different.
Motor axles usually have flats for torque washers or torque arms to grab onto to stop the axle from rotating.
They won't work for your motor.

All you can do is tighten up your axle nuts.

The 12mm axle is normally slotted to 10mm to fit a 10mm dropout.

 

[PCeBiker]

Hmm not sure if it would work since the axle on this weid motor is basically round and 10mm. M10 I think(?).

I found this info about the Grin motor,..

The image of the motor shows a torque washer with a shoulder slot on the axle for it to lock into,..

Check your motor to see if it's the same.

It sounds like that specific torque washer is your only option, and there's only one on the one side of the motor?

 

[RunForTheHills]

The description says:

G311 Torque Arm​

GRIN Front Torque Arm for G311 Motors. Replaces Disk Side Anti-Rotation Washer. Requires Fork with Fender Eyelets.

You could email them at [email protected]. They responded to a question i sent them New Year's Eve. They sell some of their small products on Amazon, but I don't know if this one will be there.

 

[PCeBiker]

The description says:

G311 Torque Arm​

GRIN Front Torque Arm for G311 Motors. Replaces Disk Side Anti-Rotation Washer. Requires Fork with Fender Eyelets.

I think I know what's going on?

There are torque washers already on the motor, and they are upside-down in this picture,..

The torque tabs need to be above the axle so that the axle sits flush into the dropouts.

I think you need to flip your torque washers 180°??

The torque arms you linked to may actually work, but you'll need to tie them off to the fork tubes somehow.

The torque washers I linked to may also work, but there may be clearance issues?

The Grin version of the torque arm is specifically designed to attach to the fender eyelets which I don't think your forks have?

The Grin version may end up being a lot of money and may not fit your forks anyway?

No use putting a ten dollar saddle on a two dollar horse, and you don't have a high power motor, so I don't think the high-end Grin version is necessary.

 

[PCeBiker]

This one might work for you as well, but there might be clearance issues with that hex bolt that connects the two pieces together??



I just found this on AliExpress:
C$19.36 | AA67-M12 Electric Bike Torque Arm Accessory For Front Rear E-Bike Motor Ebike Torque Washers Motor Safety Parts

https://a.aliexpress.com/_mNIZOqD

The torque arms that you already ordered may be your best option?
You shouldn't have any clearance issues. You just have to figure out how to strap them to your fork tubes.


And you don't have to spend any more money. (Maybe a couple stainless steel hose clamps?)

 

[PCeBiker]

By the way I feel like I should use a torque arm as well? Or do you guys not use torque arms on such small motors? Since it is a front motor I feel like my face might thank me

You are probably fine with the torque washers that are (probably) already on your motor.

I've got the same (crappy) torque washers on both my ebikes, and the one is a 750 Watt motor that gets over 1300 watts at times,..

The torque washers are sloppy and allow my axles to rotate enough to bite into the aluminum dropouts, but they didn't spin or completely wreck my dropouts.


I think your torque washers are adequate, and adding torque arms can just add a new point of potential failure in a bad place?
You don't want anything getting stuck in your brake rotor if something goes wrong.

The big thing is keeping your wheel securely attached and trying to make sure that nothing jams or seizes and throws you over the handlebars.
(The motor failing could possibly seize the motor.)

Having your front wheel fall off is even more dangerous.

I think if you just mount your motor the way it is (with the torque tabs right side up), it would be your safest and easiest approach.

(Your forks do have "laywer lips" so if your axle bolts loosen up you should hear and feel something before the wheel falls off.)


(Keep in mind that (as far as I know) front hub motors don't play nicely with suspension forks or aluminum forks, and you can break the dropouts clean off the forks and lose your wheel. I think that's for high power motors though? You might be ok with your motor, but you are going to be super-charging it.)

 

[PCeBiker]

If your motor doesn't have these torque washers, then these are the original type that came with your motor,..

https://a.aliexpress.com/_mO1X6Sp

 

[PCeBiker]

These ones look more like the originals,..

https://a.aliexpress.com/_mLzwjel

 

[harryS]

My first DIY ebike was going to be a rear drive on an alloy frame.

I posted this picture and was advised to use torque arms because the alloy frame has too many fillets and cutouts. Instead, I moved the motor over to a steel frame bike.


What was ironic was that the old 1990's mountain bikes had a 130mm dropout width, so I had to spread it out to 135 mm with a jack. Brute force, baby,


No torque arms, and the motor has never come off the bike in 10 years. No flat tires. No broken spokes. No issues at all. It originally ran on a 22A controoler, but now it has a 25 amp.

Yes, I see that the OP is living dangerously with a suspension fork conversion, Hopefully, that motor is slotted behind the threaded region for a torque washer.

You should use a torque wrench on the nuts, For years and years, I did my hub motors by feel even though I own several torque wrenches. I finally used one and found I only was torquing to about 20 ft-lbs by hand. I decided to use 26-28 ft-lbs. If one side has the cable going thru the axle, use your best estimate,

Then mark the nuts with a sharpie and make an inspection part of your pre-ride check. EVen when I was only doing them by hand, I never saw a nut move on a half dozen motors..

 

[harryS]

One more comment on Winter riding with Front wheel drive. You'll find that front wheel spinning like crazy whenever the pavement is slippery. You might think it's OK til you go uphill, and the weight shift will cause it to lose traction too.

 

[PCeBiker]

Lithium grease for example right?

One thing to note is that the grease I used was only for the gear teeth. The nylon gears have sealed bearings that I didn't lubricate.

Your gear set has an open cage squash bearing under each nylon gear that may need a different kind of grease?

You shouldn't have to get all carried away with fancy grease like I did, but there may be something best suited for your motor.


My motor had white lithium grease inside that had dried up and turned sticky. It was like clay.
There was hardly any grease left and there wasn't much to begin with.
They're always pretty stingy with the grease.
(I think they do it on purpose to shorten the lifespan so they can sell replacement motors? )