torque arms for using regen?

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torque arms for using regen?

Post by Hummina Shadeeba » Nov 15 2020 12:18pm

Any horizontal dropout torque arms for regen?



the esc does 150 amps.


https://imgur.com/a/a2dCHRm

This allows a standard hub axle to fit in a 14mm horizontal dropout, but forgetting that adapter aspect what u think of this pin/plug for dealing with regen? I’d drill a hole in the dropout for the 5mm plug/pin.


(I’ve got a two-way throttle, 20” wheel in a 24” frame that uses rim brakes so can’t run a rear brake, and my rims aren’t intended for rim brakes, so I’m all in and need to figure a regen capable torque arm for 14mm horizontal dropouts.

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Re: torque arms for using regen?

Post by Balmorhea » Nov 15 2020 2:47pm

It would probably work fine without the pin, as long as it's most/all of the way into the dropout slot. The pin will prevent you from adjusting chain tension. If you want a second torque transmitting feature, make it a slot, with a threaded hole in the dropout for a screw.
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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 15 2020 2:58pm

Balmorhea wrote:
Nov 15 2020 2:47pm
It would probably work fine without the pin, as long as it's most/all of the way into the dropout slot. The pin will prevent you from adjusting chain tension. If you want a second torque transmitting feature, make it a slot, with a threaded hole in the dropout for a screw.
yea i figured id lose the ability to tension the chain but would get a half-link chain and do the best i can.

the fear of slamming on the rear brake and having the wheel come off the back is real. so you think just a screw (m5?) going through a slot in the torque arm and into a threaded hole in the dropout is adequate? seems what youre saying just want to confirm.
150amp esc and 20" wheel. you know.

"probably work fine" kinda scares me. but with the slot in torque arm as you describe will surely be more adjustable and easier to get in and out.
and id get those nord locking washers as well i guess. and there's also the main axle nut further compressing it all...but its still relying on friction to not have the slotted torque arm slide to the rear with a hard braking.

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Re: torque arms for using regen?

Post by Balmorhea » Nov 15 2020 4:01pm

Hummina Shadeeba wrote:
Nov 15 2020 2:58pm
the fear of slamming on the rear brake and having the wheel come off the back is real. so you think just a screw (m5?) going through a slot in the torque arm and into a threaded hole in the dropout is adequate? seems what youre saying just want to confirm.
That possibility is no different for an e-bike than for a regular bike. Axle nuts or QR skewers by themselves are enough to prevent it. You also have a chain there.

How much braking force you can get is limited by tire traction and weight distribution, which means rear wheel braking force will never be very much compared to other forces applied to the axle, like motor torque or drive chain tension. Since drive chain tension is much greater than rearwards reaction force from braking, if the chain doesn't pull the wheel forward, braking surely won't pull it backwards.

I use 5mm screws to anchor my torque arms. In that case it's not just the shear strength of the screw resisting movement, but also the static friction between the surfaces being clamped by the screw (and the axle nut).
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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 15 2020 11:43pm

Balmorhea wrote:
Nov 15 2020 4:01pm
Hummina Shadeeba wrote:
Nov 15 2020 2:58pm
the fear of slamming on the rear brake and having the wheel come off the back is real. so you think just a screw (m5?) going through a slot in the torque arm and into a threaded hole in the dropout is adequate? seems what youre saying just want to confirm.
That possibility is no different for an e-bike than for a regular bike. Axle nuts or QR skewers by themselves are enough to prevent it. You also have a chain there.

How much braking force you can get is limited by tire traction and weight distribution, which means rear wheel braking force will never be very much compared to other forces applied to the axle, like motor torque or drive chain tension. Since drive chain tension is much greater than rearwards reaction force from braking, if the chain doesn't pull the wheel forward, braking surely won't pull it backwards.

I use 5mm screws to anchor my torque arms. In that case it's not just the shear strength of the screw resisting movement, but also the static friction between the surfaces being clamped by the screw (and the axle nut).
https://imgur.com/a/NN8fTJ4

And will acid etch some ridges on the 14mm horizontal dropout
Maybe throw some thin copper in as well

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Re: torque arms for using regen?

Post by dogman dan » Nov 16 2020 6:41am

Pinch it for the best possible torque arm. Lots of designs. Here is mine. In this case, the steel bike allowed me to weld one of the angle irons to the bike.
Pinch dropout, on Race bike..jpg
Pinch dropout, on Race bike..jpg (90.59 KiB) Viewed 1155 times

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 16 2020 11:39am

Thanks for your input.
I want the pinch. What u think of like this:

https://imgur.com/a/OLlFYsE

The grub screw would be pressing into the threading on the axle but wouldn’t need the threading there anymore and figure could file it a bit flatter there if need to.


And will etch some ridges in the frame’s dropouts to grab the .2mm ridges on this. Or u think the ridges aren’t needed at 150amps?

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Re: torque arms for using regen?

Post by 999zip999 » Nov 16 2020 12:15pm

How about a pic of your frame rear dropout. What rear hub motor are you using ?

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 16 2020 12:30pm

14mm bmx horizontal dropouts so it’s both a torque arm and a shim to fit the motor intended for standard dropouts.

Using the leaf 135mm spacing 1500watt motor and it’s eBay clone (two bikes).

https://imgur.com/a/B5skVv3

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 16 2020 1:09pm

999zip999 wrote:
Nov 16 2020 12:15pm
How about a pic of your frame rear dropout. What rear hub motor are you using ?

There’s so many nice bmx frames (20”-29” wheels) that use 14mm horizontal dropouts it seems worth working with those frames and adding a longer suspension fork.

https://imgur.com/a/QbNzvQ5

(24” wheel frame w 20” wheels to get a bit longer)

And many have 35.5mm downtubes and designing a battery around that as well.

https://imgur.com/a/EAtDxZV




getting these made:
https://imgur.com/a/OLlFYsE

didnt hear any feedback here saying not to. m4 bolt. 36 bucks each.

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Re: torque arms for using regen?

Post by dogman dan » Nov 17 2020 7:42am

Steel frame? If alloy, your design will still tend to crack the frame. A torque arm needs an arm. It needs the lever to connect to the frame at one of the stays.

If steel, all it needs is a good tight fit with those meaty drops. weld along the inside, then grind to fit tight as hell.

Steel will also allow the addition of any kind of pinch torque arm you like, including just replacing the dropout completely. If you don't weld, I don't either. But you can do well enough with a cheap wire feed welder.

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 17 2020 9:55am

dogman dan wrote:
Nov 17 2020 7:42am
Steel frame? If alloy, your design will still tend to crack the frame. A torque arm needs an arm. It needs the lever to connect to the frame at one of the stays.

If steel, all it needs is a good tight fit with those meaty drops. weld along the inside, then grind to fit tight as hell.

Steel will also allow the addition of any kind of pinch torque arm you like, including just replacing the dropout completely. If you don't weld, I don't either. But you can do well enough with a cheap wire feed welder.
Don’t know what u mean by weld then grind but it’s a done deal and got four of these torque arms. Steel frame. I’ll acid etch ridges on the dropout to line up w the ridges on the arm.
The challenge is 150 amps and also regen

It’s an m4 hole and will drill a flat spot on the threads of the axle for that

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Re: torque arms for using regen?

Post by 999zip999 » Nov 17 2020 2:39pm

Kool let's sy the finish product. I want to touch it

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 17 2020 7:16pm

999zip999 wrote:
Nov 17 2020 2:39pm
Kool let's sy the finish product. I want to touch it
youre too far away to touch it. come to sausalito in about 3 weeks. no naysayers on the torque arm design i guess.

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Re: torque arms for using regen?

Post by dogman dan » Nov 19 2020 7:12am

I meant if you have a thick steel dropout already, it just needs to fit perfect for it to be an effective torque arm.

So you'd add metal to the inside of one leg of the dropout with a welder, then file down to fit the actual motor. For example, your your dropout is 10mm, but it may actually measure 10.15 mm. Your motor may actually be 9.95 mm. So its .2 mm loose in the example.

So you'd add metal with a welder, then grind it flat again, so your actual dropout size is 9.96 mm.

But you got the TA's and they will work just fine on a steel frame, IF, they fit your axle tightly. If they fit loose, you will still have some rotation, forward under throttle, and rearward under braking, till it wallows out either the axle or the TA. Or it may just rock till your nuts get loose, and then you spin out the motor.

Still saying, the best possible solution for big regen forces or big acceleration forces is a pinching type dropout. Well, till you twist the axle off anyway. All you need to do to pinch is weld some angle, or square bar stock to the dropout, then bolt through another piece of similar steel. You got some nice meat there already on that steel dropout.

But again, regular TA works fine if its good and tight. This is why I just started to make my own TA's, which always fit tight as possible on any individual motor.

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Re: torque arms for using regen?

Post by E-HP » Nov 19 2020 11:50am

Hummina Shadeeba wrote:
Nov 17 2020 7:16pm
999zip999 wrote:
Nov 17 2020 2:39pm
Kool let's sy the finish product. I want to touch it
youre too far away to touch it. come to sausalito in about 3 weeks. no naysayers on the torque arm design i guess.
Well it's a torque plate, not a torque arm as pointed out earlier, so I would have designed the ridges to be horizontal instead of vertical, since they would then be perpendicular to the rotation. That said, you might be able to get away with nothing anyway, so better than that.

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 19 2020 11:56pm

dogman dan wrote:
Nov 19 2020 7:12am
I meant if you have a thick steel dropout already, it just needs to fit perfect for it to be an effective torque arm.

So you'd add metal to the inside of one leg of the dropout with a welder, then file down to fit the actual motor. For example, your your dropout is 10mm, but it may actually measure 10.15 mm. Your motor may actually be 9.95 mm. So its .2 mm loose in the example.

So you'd add metal with a welder, then grind it flat again, so your actual dropout size is 9.96 mm.

But you got the TA's and they will work just fine on a steel frame, IF, they fit your axle tightly. If they fit loose, you will still have some rotation, forward under throttle, and rearward under braking, till it wallows out either the axle or the TA. Or it may just rock till your nuts get loose, and then you spin out the motor.

Still saying, the best possible solution for big regen forces or big acceleration forces is a pinching type dropout. Well, till you twist the axle off anyway. All you need to do to pinch is weld some angle, or square bar stock to the dropout, then bolt through another piece of similar steel. You got some nice meat there already on that steel dropout.

But again, regular TA works fine if its good and tight. This is why I just started to make my own TA's, which always fit tight as possible on any individual motor.
I headed the call for the pinch and this has a grub screw. Maybe not an ideal pinch plate as you describe it but think will be workable if I drill a decent flat on the axle

I don’t want to weld.


I think the ridges being clamped by the big axle bolt will hold the dropout/adapter, and the grub screw hold the motor. And will work. And look nice and less work
Last edited by Hummina Shadeeba on Nov 20 2020 12:09am, edited 1 time in total.

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 20 2020 12:04am

E-HP wrote:
Nov 19 2020 11:50am
Hummina Shadeeba wrote:
Nov 17 2020 7:16pm
999zip999 wrote:
Nov 17 2020 2:39pm
Kool let's sy the finish product. I want to touch it
youre too far away to touch it. come to sausalito in about 3 weeks. no naysayers on the torque arm design i guess.
Well it's a torque plate, not a torque arm as pointed out earlier, so I would have designed the ridges to be horizontal instead of vertical, since they would then be perpendicular to the rotation. That said, you might be able to get away with nothing anyway, so better than that.
the ta inserts tightly into the dropout and can’t spin, or maybe the slightest back and forth possible, and I think the ridges clamped down w the big nut, won’t matter either direction of ridges. That will hold the dropout and the grub screw to hold the axle.

My concern is etching such small lines and getting them oriented exactly in line and they’re only 1mm thick. If the ridges don’t overlap right will just slide and not fall into each other. Will cnc a vinyl sticker, stick on the dropout, peel of the 1cm slits, paint it with something, then acid and electricity.

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Re: torque arms for using regen?

Post by Balmorhea » Nov 20 2020 5:00am

You're at risk of overthinking this, a lot. For most torque arms, the first thing to fail will be the flats in the axle hole of the arm. But we know most torque arms are some degree of crappy. So if you use good material, adequate thickness, close fit to the axle... then maybe you discover that the axle material isn't so great, because the flats on the axle are the new point of failure.

So you make a nice wide, conformal engagement between the axle and the torque arm-- such as what you've drawn-- and the next thing that happens is the axle snaps off at the shoulder, where the thread root meets the larger diameter. That's all the strength you get. From that point, whatever you do to further improve the engagement between torque arm and frame is wasted effort.

Unless you build a better axle, a "good" torque arm (not too thin, not too soft, not too loose-fitting, anchored against something substantial on the frame) is as much as you need. More than that, you need to have realistic expectations about how effective a flatted 10x14mm axle is as a sole form of torque retention.
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Re: torque arms for using regen?

Post by E-HP » Nov 20 2020 9:21am

Hummina Shadeeba wrote:
Nov 20 2020 12:04am
the ta inserts tightly into the dropout and can’t spin, or maybe the slightest back and forth possible
why would there be any play if you are having them machined to spec? are you using the same place that made the last crappy batch? if there's any play they are useless, send them back.

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 20 2020 11:18am

The only thing crappy is my ability to measure and also the uniformity between dropouts. They all seem a bit different. But any fitted part unless banged in is going to have a bit of play. The ridges should lock that. And the grub screw lock the axle into it.

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 20 2020 11:23am

Balmorhea wrote:
Nov 20 2020 5:00am
You're at risk of overthinking this, a lot. For most torque arms, the first thing to fail will be the flats in the axle hole of the arm. But we know most torque arms are some degree of crappy. So if you use good material, adequate thickness, close fit to the axle... then maybe you discover that the axle material isn't so great, because the flats on the axle are the new point of failure.

So you make a nice wide, conformal engagement between the axle and the torque arm-- such as what you've drawn-- and the next thing that happens is the axle snaps off at the shoulder, where the thread root meets the larger diameter. That's all the strength you get. From that point, whatever you do to further improve the engagement between torque arm and frame is wasted effort.

Unless you build a better axle, a "good" torque arm (not too thin, not too soft, not too loose-fitting, anchored against something substantial on the frame) is as much as you need. More than that, you need to have realistic expectations about how effective a flatted 10x14mm axle is as a sole form of torque retention.
I guess all depends on how much torque. U have a lot more experience. The esc does 150 amps

Maybe it’s an overkill design. Maybe my adding an extra flat spot is just what’s needed as u say the flats of the axle aren’t that great.

Will know for sure someday but at this point I’m still thinking the design is worth doing and has the potential to lock both the arm to the frame and the axle to the arm.

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Re: torque arms for using regen?

Post by dogman dan » Nov 22 2020 7:37am

Some how I missed you were having them made. IMO, the grub screw will end up being decorative, of little use unless it set into a slot machined into the axle. But still, small, very easy to break.

Design a no weld, robust plate that bolts the bike somehow, which pinches the axle. All the Gurus here have their own designs, and they work perfect for high power forward or back.

Why insist on pinch instead of just a good tight fit? You just said it, the flats are already worn, or just too short? Im not sure. But if they aren't nice flats, then you must pinch.

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Re: torque arms for using regen?

Post by Hummina Shadeeba » Nov 22 2020 11:43am

dogman dan wrote:
Nov 22 2020 7:37am
Some how I missed you were having them made.

++i tried to change the design last minute and wavered on how far to space the ridges. and i do like them perpendicular to the horizontal dropout though, and the grub screw+++

IMO, the grub screw will end up being decorative, of little use unless it set into a slot machined into the axle.

+++++i plan to machine one into the axle++++

But still, small, very easy to break.

++++you mean the m4 screw is weak or the axle?++++

Design a no weld, robust plate that bolts the bike somehow, which pinches the axle. All the Gurus here have their own designs, and they work perfect for high power forward or back.

Why insist on pinch instead of just a good tight fit? You just said it, the flats are already worn, or just too short? Im not sure. But if they aren't nice flats, then you must pinch.
the flats on the axle and bike are new. and this part getting made also is adapting to 14mm dropout (bmx). the interfaces between the axle, part, and dropout will be tight and i think the grub and ridges will lock it. i get half saying its overkill and others saying it will break. wonder if you could spot harden the motor axle and maybe it's the weak link.

what other designs for a horizontal dropout do you know and can you post a pic? or any different designs that are good, or any that showed bad? and then again how much torque were they doing and maybe the subtleties between even the bike dropout sides and materials makes a big difference.

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Re: torque arms for using regen?

Post by dogman dan » Nov 23 2020 7:42am

This thread long enough now I don't know for sure what I thought I read. I thought I saw you say the flats were somewhat rounded already.

Tight fit will work fine. Loose fit won't, whatever the design is. Pinch fit, tightest there is. The main thing I don't like about the design is that its just a robust version of a torque washer, It relies on the bike dropout essentially. It does have an arm of sorts, but its extremely short.

For big power, regen or not, I just like shit that is attached to the frame itself in at least one point. Its soooooo easy to cut your own torque plates with simple tools. 4 inch grinder to cut steel, drill, and small, flat files. The longer the arm on a torque arm, the more it can hold big torque. What you cant have with regen, is wiggle. Whatever you do, the flats have to fit tight as shit on that arm. A screw on the round side won't do shit IMO. It won't make a loose hole tight.

Just make that hole so tight you have a hell of a time getting the plate onto the axle, and it will work. Get it made too small, then hand file it to just right.

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