Front Torque Arm Installation Feedback.

[hulk]

I just finished installing two torque arms on my front fork but need feedback on if it's installed correctly (the position of the two metal brackets).

Also, I need advice on how to mount the two missing items that I have left.

One looks like washer that is cut in the middle and the other piece looks like a washer but it only goes on one way. I would really appreciate any feedback on this, thanks.

 

[JES2020]

I have no idea what the U shaped washer is for but the other is a lock washer that belongs on your axle nut.
Again. it's really hard to install those arms incorrectly.

 

[m@Robertson]

The U shaped washer goes under your torque arm so it will seat flat against your fork dropout. If your dropout has what are known as 'lawyer lips' this washer will keep the torque arm from canting as a result of them.

Google "lawyer lips" and go to the Images tab and you will instantly see what I mean by the term.

As for the torque arm, I am pretty sure you have it on backwards. Gimme a minute to go look. Honestly this style of torque arm is bottom-of-the-line and I would strongly recommend you do not use it. Literally just today I saw this picture pop up.

There are other reasons why this setup failed but look at how the hose clamps slipped down. A common failure with this style of arm.

I have seen Sooooo many of this style of arm fail. Another common issue is the fitment to the axle is seldom truly snug and it allows enough play to render the thing useless. It'll still dig into the dropout. Just say no.

 

[m@Robertson]

Yup... backwards.

"Notice that if the torque arm is mounted backwards, on the front side of the fork, then it would have the opposite effect and axle torque would tend to pop the wheel out of the dropout."

Look at this page as your guide. The Grin "Torque arm v1" was cloned by a zillion Chinese shops and it is above. Yours is not the same level of quality and they tell in the linked article why they stopped using it in favor of other designs.

Torque Arms - Grin Products - Product Info

For every force there is an equal and opposite force, and for every torque there is an equal and opposite torque. Sadly with import hub motors this opposing torque is often born entirely by bicycle dropouts that are not up to the task, allowing the motor axle to spin out. Grin has pioneered the...

ebikes.ca

Your forks are a tough match, but you definitely want to use something. The Grin arms are very thick. You might need to get creative with parts from different arms thanks to that fork construction. I suggest you spend a little extra money and use the parts from multiple arms and attach for example the V2 arm (don't even try and use the one you have) to your *brake adapter bolt* You would use a spacer and a longer M6 bolt to make that happen. I have done some like this myself and it will take some parts from eBay-sourced torque arms to make it happen. Let me see if I can find stuff on sale that will work. These things go in and out of stock all the time.

 

[m@Robertson]

OK so I am assuming you have a 12mm motor axle, which I think is highly likely. Here is one option that should work with the brake mount.

Adjustable Angle Torque Arm for e-bike 5mm Thick Stainless Steel 12x10mm | eBay

Essential for applications where the angle of the torque arm is critical. Manufactured in the UK from 5mm thick stainless steel.

ebay.us

The axle arm can be re-oriented to any position thanks to the fact its 2-piece. You connect the two pieces using the little round holes on both. that leaves the sliding channel for attachment to the M6 brake bolt. It is likely sized for an M5 so fine... hog it out with a drill bit. That will actually work better as it will prevent the thing from ever sliding. I did the same thing with this one, but I hogged it out to an M8 size (it was an M6 originally). I believe the one I am linking is smaller but thats fine for what you want to do.

Note that on paper at least the torque arm I show below is backwards too. Except I assembled it in such a way - and hogged out the channel - so the oversized dropout bolt locks it into place and it cannot move.

This seller's UK predecessor used to sell the Grin arms remanufactured under license. No idea if there is a relationship there anymore.

This seller is in the Russian Federation but he has been selling for years and he is reliable and honest. One time a shipment go lost when it hit St. Petersburg and he refunded me. This particular design in the link below will work for you without modification, but you will have to wait forever for it to arrive. But I know from experience its thick metal and sturdy. I ended up using this larger slider piece and a Grin style axle arm on a bike.

Universal Torque Arm E-Bike Electric Bicycle | eBay

Find many great new & used options and get the best deals for Universal Torque Arm E-Bike Electric Bicycle at the best online prices at eBay! Free shipping for many products!

ebay.us

 

[JES2020]

The U shaped washer goes under your torque arm so it will seat flat against your fork dropout. If your dropout has what are known as 'lawyer lips' this washer will keep the torque arm from canting as a result of them.

Google "lawyer lips" and go to the Images tab and you will instantly see what I mean by the term.

As for the torque arm, I am pretty sure you have it on backwards. Gimme a minute to go look. Honestly this style of torque arm is bottom-of-the-line and I would strongly recommend you do not use it. Literally just today I saw this picture pop up.

There are other reasons why this setup failed but look at how the hose clamps slipped down. A common failure with this style of arm.
View attachment 93972

I have seen Sooooo many of this style of arm fail. Another common issue is the fitment to the axle is seldom truly snug and it allows enough play to render the thing useless. It'll still dig into the dropout. Just say no.

The clamps are only "slid down" because they are off the wheel and slid down by the photographer to show the broken drop out !
If you think, the clamps could NOT slip down if installed on the drop outs !

Yup... backwards.

Look at this page as your guide. The Grin "Torque arm v1" was cloned by a zillion Chinese shops and it is above. Yours is not the same level of quality and they tell in the linked article why they stopped using it in favor of other designs.

Torque Arms - Grin Products - Product Info

For every force there is an equal and opposite force, and for every torque there is an equal and opposite torque. Sadly with import hub motors this opposing torque is often born entirely by bicycle dropouts that are not up to the task, allowing the motor axle to spin out. Grin has pioneered the...

ebikes.ca

Your forks are a tough match, but you definitely want to use something. The Grin arms are very thick. You might need to get creative with parts from different arms thanks to that fork construction. I suggest you spend a little extra money and use the parts from multiple arms and attach for example the V2 arm (don't even try and use the one you have) to your *brake adapter bolt* You would use a spacer and a longer M6 bolt to make that happen. I have done some like this myself and it will take some parts from eBay-sourced torque arms to make it happen. Let me see if I can find stuff on sale that will work. These things go in and out of stock all the time.

This has been discussed repeatedly

The U shaped washer goes under your torque arm so it will seat flat against your fork dropout. If your dropout has what are known as 'lawyer lips' this washer will keep the torque arm from canting as a result of them.

Google "lawyer lips" and go to the Images tab and you will instantly see what I mean by the term.

As for the torque arm, I am pretty sure you have it on backwards. Gimme a minute to go look. Honestly this style of torque arm is bottom-of-the-line and I would strongly recommend you do not use it. Literally just today I saw this picture pop up.

There are other reasons why this setup failed but look at how the hose clamps slipped down. A common failure with this style of arm.
View attachment 93972

I have seen Sooooo many of this style of arm fail. Another common issue is the fitment to the axle is seldom truly snug and it allows enough play to render the thing useless. It'll still dig into the dropout. Just say no.

and it has been verified you can not install them backwards.
The average ebike puts out 50 Newton Meters of torque,... the screw clamps used on torque arms fail somewhere around 17,000 NM, seventeen thousand !
So whether the arm runs into the fork or the clamp makes no practical difference.

 

[JES2020]

OK so I am assuming you have a 12mm motor axle, which I think is highly likely. Here is one option that should work with the brake mount.

Adjustable Angle Torque Arm for e-bike 5mm Thick Stainless Steel 12x10mm | eBay

Essential for applications where the angle of the torque arm is critical. Manufactured in the UK from 5mm thick stainless steel.

ebay.us

The axle arm can be re-oriented to any position thanks to the fact its 2-piece. You connect the two pieces using the little round holes on both. that leaves the sliding channel for attachment to the M6 brake bolt. It is likely sized for an M5 so fine... hog it out with a drill bit. That will actually work better as it will prevent the thing from ever sliding. I did the same thing with this one, but I hogged it out to an M8 size (it was an M6 originally). I believe the one I am linking is smaller but thats fine for what you want to do.

View attachment 93977

This seller's UK predecessor used to sell the Grin arms remanufactured under license. No idea if there is a relationship there anymore.

This seller is in the Russian Federation but he has been selling for years and he is reliable and honest. One time a shipment go lost when it hit St. Petersburg and he refunded me. This particular design in the link below will work for you without modification, but you will have to wait forever for it to arrive. But I know from experience its thick metal and sturdy. I ended up using this larger slider piece and a Grin style axle arm on a bike.

Universal Torque Arm E-Bike Electric Bicycle | eBay

Find many great new & used options and get the best deals for Universal Torque Arm E-Bike Electric Bicycle at the best online prices at eBay! Free shipping for many products!

ebay.us

Unfortunately that set up is not ideal. It allows the axle to to spin in the dropout if the screw holding position in the slide gets loose !
The whole purpose of the arm is to prevent the axle spinning in the dropout !

 

[m@Robertson]

Unfortunately that set up is not ideal. It allows the axle to to spin in the dropout if the screw holding position in the slide gets loose !
The whole purpose of the arm is to prevent the axle spinning in the dropout !

No it doesn't You reverse that position. See my comments above. You hog out the M5-sized channel so it takes an M6 on the brake bolt mount. Then it can't slide. And since its 5mm thick stainless steel, there's plenty of material left so there will never be a problem. Especially on the pictured 60Nm motor.

 

[m@Robertson]

The clamps are only "slid down" because they are off the wheel and slid down by the photographer to show the broken drop out !
If you think, the clamps could NOT slip down if installed on the drop outs !

This has been discussed repeatedly


and it has been verified you can not install them backwards.
The average ebike puts out 50 Newton Meters of torque,... the screw clamps used on torque arms fail somewhere around 17,000 NM, seventeen thousand !
So whether the arm runs into the fork or the clamp makes no practical difference.

Read the Grin article. The people who designed this specific torque arm. They are specific on this. Its backwards and instead of that style of torque arm pushing the axle further into the dropouts, it wants to lever it out of the axle instead.

And the arms slide down because these crappy axle arms do not have a precise fit to the axle, which lets them rock. Which then either snaps the dropout or the arm on the fork blade is not secure enough to prevent the further deterioration of the rigid hold on the axle arm and it fails, with the result being the axle arm spins and it tears the blade arm straight down as seen in that pic.

My first and only failure of a torque arm was one of these and it happened in exactly that fashion.

 

[JES2020]

I just finished installing two torque arms on my front fork but need feedback on if it's installed correctly (the position of the two metal brackets).

Also, I need advice on how to mount the two missing items that I have left.

One looks like washer that is cut in the middle and the other piece looks like a washer but it only goes on one way. I would really appreciate any feedback on this, thanks.

I found this video...that U shaped washer is specific to front wheel installation and is clearly explained at around 1:36 min.
Just remember that those hose clamps are go to 17,000 NM before failure, and you will understand why it doesn't mater which side of the fork the torque arm is positioned. Not to worry
Try that again.
Weird
You can find it by searching on youtube:

Ebikeling Torque Arm Installation​

 

[m@Robertson]

The average ebike puts out 50 Newton Meters of torque,... the screw clamps used on torque arms fail somewhere around 17,000 NM, seventeen thousand !

I think you are using numbers that are associated with the band snapping. Thats not the problem. The problem is the band sliding down the fork blade. Thats not going to need 17000Nm. It happened on my fork with an 80Nm motor that had a 35a controller/52v battery.

And we do have to look at the job the OP is trying to accomplish. He's not running a Qsv3 here pulling 3kw. Its a little 60Nm motor. Two torque arms installed properly - even these - are going to be sufficient. But... they suck. Plain and simple. As I said its the very bottom of the barrel. I wouldn't use them and I see them fail repeatedly.

 

[m@Robertson]

I found this video...that U shaped washer is specific to front wheel installation and is clearly explained at around 1:36 min.
Just remember that those hose clamps are go to 17,000 NM before failure, and you will understand why it doesn't mater which side of the fork the torque arm is positioned. Not to worry

Yeah it fits above the lawyer lips so the torque arm stays flat. Looks like he doesn't need to worry about it and can leave it off. I use thin ridged round lock washers instead.

A quick and dirty/weird link but it states the purpose pretty neatly. "Provides a level dropout surface for installing hub motors"

https://angola.desertcart.com/products/10739644-c-washer-for-front-forks-with-lawyer-lips

EDIT:

Here, someone has already labeled it on one of the many how tos. You put the U straight down. the washer fits into the slot created by the lawyer lips. Its taller than the lips so now you get a flat surface.

 

[JES2020]

No it doesn't You reverse that position. See my comments above. You hog out the M5-sized channel so it takes an M6 on the brake bolt mount. Then it can't slide. And since its 5mm thick stainless steel, there's plenty of material left so there will never be a problem. Especially on the pictured 60Nm motor.

So you drill out the channel to prevent sliding. Seems like there must be a simpler way to make it safe.
But anyway, thats for a rear wheel installation, the OP has front wheel installed.

 

[JES2020]

I think you are using numbers that are associated with the band snapping. Thats not the problem. The problem is the band sliding down the fork blade. Thats not going to need 17000Nm. It happened on my fork with an 80Nm motor that had a 35a controller/52v battery.

And we do have to look at the job the OP is trying to accomplish. He's not running a Qsv3 here puylling 3kw. Its a little 60Nm motor. Two torque arms installed properly - even these - are going to be sufficient. But... they suck. Plain and simple. As I said its the very bottom of the barrel. I wouldn't use them and I see them fail repeatedly.

Please re read the reason the clamps are slid down in you pic that I posted. The channel in the torque arm for the clamps absoulutly prevent them from sliding down the fork with the arm installed on the axle and bolts (even loosely in place)

 

[JES2020]

Yeah it fits above the lawyer lips so the torque arm stays flat. Looks like he doesn't need to worry about it and can leave it off. I use thin ridged round lock washers instead.

A quick and dirty/weird link but it states the purpose pretty neatly. "Provides a level dropout surface for installing hub motors"

https://angola.desertcart.com/products/10739644-c-washer-for-front-forks-with-lawyer-lips

EDIT:

Here, someone has already labeled it on one of the many how tos. You put the U straight down. the washer fits into the slot created by the lawyer lips. Its taller than the lips so now you get a flat surface.
View attachment 93978

View attachment 93979

 

[JES2020]

Lol, you make me smile. I just posted the video explaining it. Is there an echo echo echo ?

 

[m@Robertson]

Lol, you make me smile. I just posted the video explaining it. Is there an echo echo echo ?

Look up the video doesn't work. And why bother posting the video when the first sentence of my first post already did that. In one sentence.

 

[m@Robertson]

Please re read the reason the clamps are slid down in you pic that I posted. The channel in the torque arm for the clamps absoulutly prevent them from sliding down the fork with the arm installed on the axle and bolts (even loosely in place)

Yeah I read it. I've seen them slide down. On my own miserable failure of a first bike build, and repeatedly over on the DIY FB groups where there are plenty of boneheads who don't do careful work.

This illustration is similar to the one on the Grin page but its different enough to make the issue easier to grasp.

The chief difference is the direction of torque on the axle. The arrow shows it acts on the torque arm down and forward. Using the lever that is the axle-mounted arm, That lever is pulling straight down on that blade-attached torque arm. When it fails, (i.e. the dropout snaps) the unrestricted torque of the motor pulls that blade mounted arm straight down. Especially if its loosely attached as you say. But since many forks have decreasing diameters leading down to the dropouts, even a tight fit can give way with a hard tug.

The Grin V3 arm addressed this weakness in design by giving the blade-mounted arm two or even three different locking points. But its the wrong tool for the job for the OP's situation.

 

[JES2020]

Read the Grin article. The people who designed this specific torque arm. They are specific on this. Its backwards and instead of that style of torque arm pushing the axle further into the dropouts, it wants to lever it out of the axle instead.

And the arms slide down because these crappy axle arms do not have a precise fit to the axle, which lets them rock. Which then either snaps the dropout or the arm on the fork blade is not secure enough to prevent the further deterioration of the rigid hold on the axle arm and it fails, with the result being the axle arm spins and it tears the blade arm straight down as seen in that pic.

My first and only failure of a torque arm was one of these and it happened in exactly that fashion.

Are you saying that your front wheel shot straight down and off of the axle???
There are so many issues with that scenario, first being your axle nuts must have been barley on and you must have been doing some sort of wheelie with a front motor??? It's to confusing to contemplate.
Keeping the wheel on the axle is a side benefit, but not the major purpose of a torque arm, which is to prevent axle rotation IN the drop out, which is what causes the drop outs to shear away from the fork , as shown in your pic.

 

[tomjasz]

Look up the video doesn't work.

Another one-off, maybe one, a builder that is suddenly an expert. There's no use in trying to educate the "expert".