Installing torque arms on felt faker frame

[xXSaneXx]

Im building a 750w felt faker gas frame into a electric bike. Im using a FRONT 750w 20x4inch hub on the REAR of my bike. I apologize for capitalizing those 2 words as when I talk bout this build to others it confuses them for some reason. Anyway my frames the 3.4L felt faker frame with the 135mm rear dropouts. It is a high grade aluminum frame. The dropouts are nice an meatie an built pretty nice as these frames are used to race gas bikes pushing 16+hp an running high speeds at 10,000rpms. Any way my question, im having a issue on torque arm placement. I could use just the washer an line it up to a hole but in other to do that id need to use a bolt an slip it in the hole from the inside an use tape to hold it on preventing it from falling out as I slide wheel into place. Id need bolts to get a wrench on (these kits only come with hex bolts) an a nut going on from the outter side to tighten it.
Or could I use the torque arms with the steel clamps? Im not sure where to place them though, are the spots im holding them a possibility?
If I went through the hole above the axle would it be strong enough for 750w? Id be doing this on both sides. Thanks for any help. I did research but most things I found were for high powered hubs.

 

[Apartunis]

When I have a dropout plate that big to work with, I set a torque arm axle plate in whatever way gives me a good location for the screw. Then I punch though the screw hole to mark it, drill and tap straight into the dropout.

 

[xXSaneXx]

When I have a dropout plate that big to work with, I set a torque arm axle plate in whatever way gives me a good location for the screw. Then I punch though the screw hole to mark it, drill and tap straight into the dropout.

The bolt above the axle does line up if i turn that torque arms washer around like this. Would that work? Would the m6 bolts be strong enough?

 

[Apartunis]

The bolt above the axle does line up if i turn that torque arms washer around like this. Would that work? Would the m6 bolts be strong enough?

That is as good as any other arrangement if not better.

 

[offGridDownUnder]

The pictures lead me to think that you are connecting a 750W motor to a torque arm via axle flats. Are the materials of the torque arm and the axle hard/strong enough for the repeated torque?

This will be especially of concern if you are using regen braking, as that will be loading the axle/arm interface back and forth. But with sufficient torque, it might round off the axle anyway.

I'm just posing the question. Others with more knowledge/experience may have the answer.

 

[xXSaneXx]

The pictures lead me to think that you are connecting a 750W motor to a torque arm via axle flats. Are the materials of the torque arm and the axle hard/strong enough for the repeated torque?

This will be especially of concern if you are using regen braking, as that will be loading the axle/arm interface back and forth. But with sufficient torque, it might round off the axle anyway.

I'm just posing the question. Others with more knowledge/experience may have the answer.

Theres no regen. Its just a 750w front hub mounted to rear. It has the standard 10mm/12mm axles that slide in the 10mm dropouts via flat side of axles. The torque arms im using are 10mm/12mm also. Stopping will come from front and rear 4 piston hydraulic brakes with a set of 203mm rotors.

 

[Apartunis]

A single torque arm correctly fastened plus tabbed washers is all I would use for a 2kW gross power system (so like a 1kW commercial bike). I do not think this one is likely to be an issue as long as the axle nuts get tightened appropriately.

 

[xXSaneXx]

A single torque arm correctly fastened plus tabbed washers is all I would use for a 2kW gross power system (so like a 1kW commercial bike). I do not think this one is likely to be an issue as long as the axle nuts get tightened appropriately.

I thought dual torque arms were recommended for a aluminum frame though.

 

[99t4]

Are those photos of your TAs? They look suspiciously like the sloppy cheap knockoff clones of the long-discontinued earliest Grin TA version that they discontinued several years ago because of several problematical design aspects.

I bet the rotational fit on the axle is loose and can rock back and forth on the flats. Most all these clones of this design have axle hole cutouts that are slightly too big and even this minute sloppiness allows the axle to rock back and forth, chewing away at the TA/dropout/axle, worsening over time, until something there totally fails.

Sometimes however they can be made to work (if no regen) if you are able to "clock" it in the right position. Every time it is disturbed (tire changes for example).

 

[xXSaneXx]

Are those photos of your TAs? They look suspiciously like the sloppy cheap knockoff clones of the long-discontinued earliest Grin TA version that they discontinued several years ago because of several problematical design aspects.

I bet the rotational fit on the axle is loose and can rock back and forth on the flats. Most all these clones of this design have axle hole cutouts that are slightly too big and even this minute sloppiness allows the axle to rock back and forth, chewing away at the TA/dropout/axle, worsening over time, until something there totally fails.

Sometimes however they can be made to work (if no regen) if you are able to "clock" it in the right position. Every time it is disturbed (tire changes for example).

Cheap? Idk but they are steel an decently thick. Idk bout the knockoff. These dont rock back an fourth like you mentioned. It seems these have mixed opinions. Some say they work, an some say they dont. So it makes me question who's right an who is wrong lol

 

[E-HP]

Cheap? Idk but they are steel an decently thick. Idk bout the knockoff. These dont rock back an fourth like you mentioned. It seems these have mixed opinions. Some say they work, an some say they dont. So it makes me question who's right an who is wrong lol

I break off small pieces of razor blade and use them as shims. You can jam them between the axle flat and torque are with a chisel or screwdriver to get rid of any movement.

 

[xXSaneXx]

Would this be a better route to go as it looks like I could bolt the arm to both holes on my frame. Thoughts? The 2 holes below the disc brake adapter is what im referring to.

 

[99t4]

These dont rock back an fourth like you mentioned.

Poor quality control, most of these I've seen are a loose fit. Looks like you got a good tight fitting one, so carry on.

Would this be a better route to go as it looks like I could bolt the arm to both holes on my frame. Thoughts?

Maybe, maybe not. Since you already have a tight fitting TA (the most important aspect) why not use it?

I would flip it 180 and mark and drill and tap a hole for it (where I marked in green). That large flat dropout is a TA installer's dream!



What happened to this orientation? It seems perfect.

 

[xXSaneXx]

Poor quality control, most of these I've seen are a loose fit. Looks like you got a good tight fitting one, so carry on.


Maybe, maybe not. Since you already have a tight fitting TA (the most important aspect) why not use it?

I would flip it 180 and mark and drill and tap a hole for it (where I marked in green). That large flat dropout is a TA installer's dream!

View attachment 388955

What happened to this orientation? It seems perfect.
View attachment 388956

I read an was told its to close to the brake mount since its an aluminum frame. And I get mixed opinion on mounting it like that. Its a hole in the frame (same spot on both sides) meant for either a gear selector or fenders(not sure an no Felt Faker owners can tell me) haha!
That holes not threaded but if I get a bolt big enough that will fit, I should be able to make a thread into it. The brake mount bolts are to small. I think they are 5m. So maybe its a 6m?

 

[99t4]

I read an was told its to close to the brake mount since its an aluminum frame.

Who told you that? It's not that close.

That holes not threaded but if I get a bolt big enough that will fit, I should be able to make a thread into it.

Do yourself a favor and do it the right way. Get or borrow or find the correct thread tap tool.

So maybe its a 6m?

Maybe. So see if a M6 tap can tap it. Fender mount bosses (and water bottle mount bosses) I'm pretty sure are M5x.08.

Now I'm curious. How did you get the holes to line up, and not line up in your different photos?

 

[xXSaneXx]

Because it has that much play...
Someone on fb before I posted about this here.
The hole above it is threaded but it wont reach.

 

[offGridDownUnder]

Because it has that much play...

Oh, so you think it's going to move around a lot on the axle?

Just sayin'...

Sorry, I couldn't resist Best of fortune with it, really.

 

[xXSaneXx]

Oh, so you think it's going to move around a lot on the axle?

Just sayin'...

Sorry, I couldn't resist Best of fortune with it, really.

Idk.. thats why im asking for help haha! So do you think it will? Because I dont know.

 

[99t4]

Because it has that much play...

These dont rock back an fourth like you mentioned. It seems these have mixed opinions. Some say they work, an some say they dont. So it makes me question who's right an who is wrong lol

You'll have to decide. I can't help you anymore from here, sorry. Do the best you can.

 

[Apartunis]

Because it has that much play...
Someone on fb before I posted about this here.
The hole above it is threaded but it wont reach.

That's actually good as long as you are not using regen braking or a sensorless controller.

Because those two things can cause frequent torque reversal, you would need to limit any ability for the axle to slop to and fro. But if you only have forward motor torque then all reaction torque is reverse from that. So if your TA must be rotated all the way forward to bolt it down then it has no place to go when the motor is pushing. That is ideal but it is also super easy to install and remove because of relative looseness.

 

[Apartunis]

Oh, so you think it's going to move around a lot on the axle?

It will not if the motor only ever torques in one direction.

 

[xXSaneXx]

It will not if the motor only ever torques in one direction.

Qs far as I know theres no regen. Brakes as I have no brake sensors. Im using just 4 piston hydraulic brakes. Its a powallon 750w front hub on rear. 135mm 20x4inch wheel. Came with a 25amp controller with plugs for motor,battery, headlight, full twist throttle, an a pedal assist sensor. Nothing about regen braking though

 

[offGridDownUnder]

AFAIK without regen or other reversing, you can be ok.

I think that after you assemble the rear wheel then when you ride it will shift the looseness out of the torque arm/axle/nut. Perhaps ride it a short distance to set it, and then re-tighten the axle nut? Probably without loosening the axle nut completely.

 

[E-HP]

Because it has that much play...
Someone on fb before I posted about this here.
The hole above it is threaded but it wont reach.

Is the play all in the torque arm to axle fit, or is there a lot of play between the axle flats and the dropouts?

 

[xXSaneXx]

Is the play all in the torque arm to axle fit, or is there a lot of play between the axle flats and the dropouts?

The dropouts it fits fine like it should. The torque arm washer is what has play. The 2 pics one where im holding it in place an the other where I let it sit freely. So if I put a bolt in place an nut to hold it in place.