Torque Arm Placement?

[geeeyejo1]

Just received my Ebike Torque Arm from Ebikekit.com. Those with more experience, please let me know if this placement will work. I initially tried installing with arm secured to bottom dropout but seemed like if torque arm was turned by axle that it would pull along bottom dropout rather than against it. Secured to vertical frame arm it appears that the geometry is better...

 

[NeilP]

No, underneather is better..so when it tries to turn it pushes against the frame.

As you have it there, the torque of the wheel turning will try to pull it away from the frame. You want it pushing against the frame so the pipe clip is only securing it in place not taking the strain..Till you use regen braking.

Think about it..the wheel is tryign to turn forward. if it can't turn forward, then the axler will try to turn in the opposite direction. So in your picture the torque arm will try to turn clockwise.

it will spin clockwise like this, see my clever use of the wiring as a torque arm here , stopping the axle spinning any further

 

[geeeyejo1]

No, underneather is better..so when it tries to turn it pushes against the frame.

it will spin clockwise like this, see my clever use of the wiring as a torque arm here , stopping the axle spinning any further

Lol - I could have saved $27 using my wiring! I get it, makes sense - time to undo and redo!

 

[dnmun]

it will work as it is. you want the joint with the bolt to be at right angles. which is what you got now. the joint where the bolt is will twist if it has torque applied in rotation. you want it to pull at right angles.

 

[NeilP]

Well yes, it will work, but the strain is pulling on the pipe clip ..so all the strain is on the pipe clip. You should be able to mount it so the arm is at right angles and have it underneath too

If you need to add an image..crop to smaller dimensions..either less that 800 or 500 and then it will display

 

[geeeyejo1]

Ok, placed it so it would be pushing the bottom frame bar. Bent arm slightly so it is centered along bottom frame. Was a little puzzled though - the part that goes around the axle bolt has a little bit of play - does not appear to be an exact 10mm opening like the dropout which is very tight against the axle bolt...

 

[NeilP]

re sized to 800 wide.

Yea, these ready made torque arms are not a great fit, but adequate for lower power levels.
If you go mad you will need to go with a clamping arrangement

 

[NeilP]

My clamping torque control system..with home turned axle..from this thread

 

[geeeyejo1]

My clamping torque control system..with home turned axle..from this thread

Wow - great job - that level of ingenuity and fabrication skill is amazing in my book!

 

[NeilP]

Was my first time using any of that sort of kit too. had to turn the axle and use the milling machine ..learning as I went.. OK I had some basic usage training ..20 years ago at engineering college, but never actually done any practice since then

 

[dogman dan]

Pushing on the frame is always best, but if impossible, pulling will work ok if the forces are moderate, such as 36-48v with only 20 amps controllers.

Once you go to big power, clamping torque plates rule in my opinion. Here's a simple version for a steel bike. Weld a piece of fairly thick angle to the frame, then bolt though another to clamp, or pinch the axle. In this case, I just have this on one side. Normal bolt on the derialur side.

 

[autodoctor911]

re sized to 800 wide.

Yea, these ready made torque arms are not a great fit, but adequate for lower power levels.
If you go mad you will need to go with a clamping arrangement

the first part of the torque arm will try to rotate clockwise in this photo, but the longer part is attached by one bolt, so introduces another pivot, creating a push-rod effect in the longer part of the "torque arm". If the attachment point to the frame is not constrained in the fore/aft direction in this photo(the only thing doing so in the pic is the friction against the clamp or frame), the torque arm is doing nothing. If the Dropout is tight on the axle and the torque arm is loose, it also does nothing until the frame is already damaged. If you really need a torque arm for the amount of torque you are generating, and you want to use this cheesy torque arm setup to do so, you should turn the slack in the small part till it stops in the clockwise direction in the photos, then cut down the longer link and drill another hole to line up with the rack eye, and use a longer bolt to secure the rack and the torque link to the frame.

For a torque arm setup with 2 pieces that can pivot where they attach, you basically have a short torque arm connected to a link. the best method for attaching the link would be in a direction that uses it in tension, or as a pull-rod. You can do it the other way, and use it as a push-rod, but it won't be quite as string. The most important thing however is that it be restrained from motion in the direction that is nearly perpendicular to the line between the axle and the bolt that attaches it to the actual torque arm(the smaller part).

 

[geeeyejo1]

re sized to 800 wide.

Yea, these ready made torque arms are not a great fit, but adequate for lower power levels.
If you go mad you will need to go with a clamping arrangement

the first part of the torque arm will try to rotate clockwise in this photo, but the longer part is attached by one bolt, so introduces another pivot, creating a push-rod effect in the longer part of the "torque arm". If the attachment point to the frame is not constrained in the fore/aft direction in this photo(the only thing doing so in the pic is the friction against the clamp or frame), the torque arm is doing nothing. If the Dropout is tight on the axle and the torque arm is loose, it also does nothing until the frame is already damaged. If you really need a torque arm for the amount of torque you are generating, and you want to use this cheesy torque arm setup to do so, you should turn the slack in the small part till it stops in the clockwise direction in the photos, then cut down the longer link and drill another hole to line up with the rack eye, and use a longer bolt to secure the rack and the torque link to the frame.

For a torque arm setup with 2 pieces that can pivot where they attach, you basically have a short torque arm connected to a link. the best method for attaching the link would be in a direction that uses it in tension, or as a pull-rod. You can do it the other way, and use it as a push-rod, but it won't be quite as string. The most important thing however is that it be restrained from motion in the direction that is nearly perpendicular to the line between the axle and the bolt that attaches it to the actual torque arm(the smaller part).

Well this really pisses me off a bit as Ebikekit.com advertises this as a "Universal Torque Arm" and provides no install instructions with the torque arm and minimal info on their site. The metal even appears different from the pic on their site (pic on site appears to be stainless, this almost looks plated). I did remove any play against the axle prior to installing but I can see what you mean - regardless of install position, if you are using the clamp the tendency would be for the torque arm to slide up the frame rather than push (or pull) against it... I honestly believe that the Cromo Steel frame on this Gary Fisher will prevent the axle from bending it. I may consider repositioning and utilizing the rack mount or may just keep as is and just use it to prevent wheel from spinning if frame gives way...

 

[dogman dan]

Universal for it's design application limits, which are NOT 3000w. Get the bolt tight enough, and up to 1000w should be ok. Justin does test the stuff he designs by the way. I personally sent him several forks to use in his torque arm/fork testing to destruction.

A few ways to fix it. One is to fit the torque arm, tighten the pivot bolt, and then weld it into that position. Now it's not universal anymore, but fitted to that bike only.

Another option is to find a way to prevent the slip of the arm up the frame tube. If steel, you could weld a tab to it, then bolt to the tab. I ran 4000w through a motor this way, with no problems with slippage.

Oh, and that's a front torque arm you are using in the back BTW. You might find a better fit if you bought Justins universal REAR torque arm.