Strongest clamp for torque arm?

[bowlofsalad]

In the pursuit of knowledge concerning torque arms, I came across something written by dogman. 'Hose clamps are just decorative ways to keep a torque arm on your bike.' http://www.mcmaster.com/#t-bolt-hose-clamps/=meydve I have read these and something called herbie clip are supposed to be strong, stronger at least than a standard hose clamp.

It boils down to asking if there is anything else that can be used besides and considered good enough beyond what is done in the picture attached.

I am sure each situation is circumstantial. According to the simulator, the motor may be capable of putting out close to 90nm of torque.

 

[HAROX]

Short answer: none of them (yeah well, opinions are like lock nuts)
A torque arm permanently sealed to the surface will work unless it shears off. Call the force air pressure, since there is no space for air to compromise the fit.
A hose clamp has a spiral gear design. It works well for hoses, however using it to fix a torque arm in place of welding or super epoxy is denying the inevitable. Just knowing I can break hose clamps at will, by the box full :lol:

 

[dogman dan]

Best bet would be a strap of medium thick steel, perhaps as thick as a dime. Bend it and secure the torque arm with a bolt. Typical plumbers strap is just a tad thin. Strap it very tight, so it cannot slip up and down the fork.

Or find a vintage hose clamp, one made in the USA perhaps 20 years ago or longer. It's the current generation of clamps that are so weak. The metal housing of the screw is tinfoil.

For serious applicaton of power, I welded steel tabs to the forks, and used two bolts to bolt the arm to the forks. This was for a race, and I was running 4000 watts. No problems. But not required for 1000-1500w.

 

[pendragon8000]

this image you posted.. well if you look at the leverage thats at work IMO its not good, well its ok but really there is still alot of movemnt that can occur before a critical failure.

i used builders plate bent as dogman sugested and it seems very good. only used a hose clamp for the first time on a new build recently and realised it was utter shit. i used 2 large ones but still i could tell it was a mistake.

this is how to make a torque arm and secure it: (like a boss)

 

[friendly1uk]

These are strong http://www.mikalor.com/eng/company/mikalor-hose-clamps/3-high-pressure/abrazadera-supra-inoxidable-w5/

I'm not recommending you use them for your given purpose. I'm just showing you some strong clamps. A good 316 band for salty conditions(if they salt your roads)and the screw threads in to metal bar, not thin plate. These bars can rotate, so they tend to pull up a little more evenly, and not oval for fun.

 

[Harold in CR]

What about conduit straps that are used for fastening metal conduit to walls ?? They are galvanized and have a ridge formed in them, for firm holding. Have to measure how long they would be wrapped around the frame-fork, but, these are not slotted or anything, except for the nail-screw holes on each end.

The ones for 1¼" conduit should be close to the right size. It would allow for squeezing with a grade 5-¼" bolt and nylock nut, maybe ?

 

[bowlofsalad]

What about conduit straps that are used for fastening metal conduit to walls ?? They are galvanized and have a ridge formed in them, for firm holding. Have to measure how long they would be wrapped around the frame-fork, but, these are not slotted or anything, except for the nail-screw holes on each end.

The ones for 1¼" conduit should be close to the right size. It would allow for squeezing with a grade 5-¼" bolt and nylock nut, maybe ?

That sounds like a good idea. Some conduit straps I see at first glance appear super brutal. I was trying to imagine a way to use steel cable or something similar, but conduit strap looks interesting.

 

[Harold in CR]

If you can get the size narrowed down, the strap-clamp should squeeze down firmly and not allow ANY movement of the torque arms.

 

[Ykick]

I generally use these - http://www.mcmaster.com/#pipe-routing-clamps/=mf29vi

EDIT - dunno why it won't link to the proper page but it's the vinyl-coated Loop clamps. I also use them for controller brackets and other frame mount needs.

Not because they're all that great but I had a bunch laying around and the're holding up very well for under 2kW rear DD motors.

 

[friendly1uk]

Have a look at hospital saddles if you like conduit bits. There cast bases may interest you, rather than the strap.

 

[Drunkskunk]

Try a "P clip" for a coaster brake. They are just a strap of metal that goes around the chain stay, then has a bolt hole for the coaster brake arm, or a torque arm. And they are a lot stronger than a hose clamp.

 

[-dg]

Try a "P clip" for a coaster brake. They are just a strap of metal that goes around the chain stay, then has a bolt hole for the coaster brake arm, or a torque arm. And they are a lot stronger than a hose clamp.

Perfect. It's almost as if there was a bicycle specific solution to the problem of reacting torques on a bicycle.

 

[aroundqube]

Are you writing a book?

 

[dogman dan]

What made my welded and bolted torque arm strong was the fact that two bolts secured it. So that's a good idea to incorporate into a strap as well.

With two bolts, the second piece is unable to pivot, therefore the bolt connecting the two pieces could even be loose and the arm would still hold.

Whatever it looks like to you, it passed the test on the racetrack. There was one on each side of the fork.

Nothing wrong with your rear torque arm design. That's looks much stronger than mine. Pinch torque arms rule.

 

[pendragon8000]

Just had a look at bowlofsalad's picture again and I think I may have been a bit harsh in my obove comment. Its just the arm is quite short so running very high power (3kw+) might not be a good idea.

 

[biohazardman]

I cut a heavy wide hose clamp and bent the metal to shape, around the chain stay, then drilled it for a bolt on my last build. It's twice as thick as a normal clamp and I put a couple of large, for my usage, washers on the bolt and nut to cinch up tight. So no play here and that is an important item to look at when installing a torque arm. Any amount of play things will wear and eventually let go.

 

[dogman dan]

In case it's not so clear, that pic bowl of salad posted was my death race bike from a few years back. Building a bike to go 47 mph with a front hub motor was definitely not a good idea.

But I just had to try it anyway. It had plenty of problems, but the torque arms were not one of them.

FWIW, my commuter bike has been running for about 3 years now, with two the same torque arms from grin on it's alloy front shocks. Secured by hose clamps. No problems. That's running 48v 20 amps.

On another bike, I run 48v 40 amps, on a 5304 rear motor. Two torque arms, but they bolt on. No hose clamps for that one. Another bike runs 72v 40 amps, and that one has a bolt on pinch dropout on the disk brake side. So my torque control device gets more and more secure, the more I expect it to do.

For "normal" ebikes, two arms and two decent hose clamps are fine. A hose clamp gets useless if you ask it to do more than it was designed for, but not if it's kept inside normal limits that Justin designed the device for. You may have to try a few different sources for hose clamps though, if the first try is china typical.

But even though a decent hose clamp is strong enough for a normal ebike, if you are going to worry about it, replace it with a strap and bolt that is obviously able to hold more force. Then ride happy.

Bear in mind, almost every case where a torque arm is actually needed, either the motor is very high powered, or the motor has not been fitted to the bike properly. The c washers may be far far far more important than the torque arm. If you have a 14mm axle, I highly recommend filing the bike dropout deeper by 2mm. Get the axle center in the center where it belongs.

 

[bowlofsalad]

I guess I struggle to imagine how you could accurately secure something that wasn't close to made to the length needed on a chainstay. I imagine that it might be hard to get things as tight as something that you can tighten like a hose clamp. Maybe I need some pictures to help me with the mental illustration.

I can imagine if you cut the piece short enough, a flat piece of metal about as thick as a dime, and roll it into a U shape, and them drill holes at each end, the tightening could be done with the bolt and nut this way. I doubt I am explaining this right.

http://www.youtube.com/watch?v=F7w4XKQ5j_s This video actually looks exactly like what I am imagining.

Where would someone purchase builders plate?

http://www.youtube.com/watch?v=608jppPC9xY This video looks like a great demo on making round clamps, super tough stuff it looks like.

 

[dogman dan]

The clamp in the video looks ideal, if you can source the right size. Or create something similar. Might find stuff like that cheap in a junkyard from a car.

Any lumberyard will have builders plate.

Custom make the strip of metal, fit it tight, drill the hole and bolt it. It might be best to shim the metal strip with something to get it very tight and immovable. Strip of plastic cut from a bucket, or some such thing. Whatever results in tightening the clamp to really grab the hell out of the chain stay. Fit the strip, then add the shim so it gets tighter than when you drilled the hole is what I mean.

 

[bowlofsalad]

The clamp in the video looks ideal, if you can source the right size. Or create something similar. Might find stuff like that cheap in a junkyard from a car.

Any lumberyard will have builders plate.

Custom make the strip of metal, fit it tight, drill the hole and bolt it. It might be best to shim the metal strip with something to get it very tight and immovable. Strip of plastic cut from a bucket, or some such thing. Whatever results in tightening the clamp to really grab the hell out of the chain stay. Fit the strip, then add the shim so it gets tighter than when you drilled the hole is what I mean.

I found a supplier on ebay, http://www.ebay.com/itm/MIKALOR-W2-Stainless-Supra-Heavy-Duty-Hose-Clamp-Exhaust-Pipe-Turbo-Clip-Jubilee-/140671164843?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item20c0a7a1ab that seems to have a bunch of different sizes available. The issue would be with that is picking out the right size, it seems they have a pretty small span of potential acceptable sizing. They have a chart on their ad that lists the torque each size can handle. Sounds pretty tough, maybe plenty suitable for an ebike? I don't really know for sure.
I imagine using a piece of string wrapped tightly around the chainstay with the torque arm in place would give a pretty solid idea of what diameter round clamp would be needed.

I imagine that maybe some neoprene or something like that might make a good shim material, if I understand what you mean. Rubber, maybe plastic, something that really grips.

 

[Ykick]

The clamp in the video looks ideal, if you can source the right size. Or create something similar. Might find stuff like that cheap in a junkyard from a car.

Any lumberyard will have builders plate.

Custom make the strip of metal, fit it tight, drill the hole and bolt it. It might be best to shim the metal strip with something to get it very tight and immovable. Strip of plastic cut from a bucket, or some such thing. Whatever results in tightening the clamp to really grab the hell out of the chain stay. Fit the strip, then add the shim so it gets tighter than when you drilled the hole is what I mean.

I found a supplier on ebay, http://www.ebay.com/itm/MIKALOR-W2-Stainless-Supra-Heavy-Duty-Hose-Clamp-Exhaust-Pipe-Turbo-Clip-Jubilee-/140671164843?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item20c0a7a1ab that seems to have a bunch of different sizes available. The issue would be with that is picking out the right size, it seems they have a pretty small span of potential acceptable sizing. They have a chart on their ad that lists the torque each size can handle. Sounds pretty tough, maybe plenty suitable for an ebike? I don't really know for sure.
I imagine using a piece of string wrapped tightly around the chainstay with the torque arm in place would give a pretty solid idea of what diameter round clamp would be needed.

I imagine that maybe some neoprene or something like that might make a good shim material, if I understand what you mean. Rubber, maybe plastic, something that really grips.

I'm not feeling the love with those. As you noticed the minimal adjustment range plus where does the TA attach?

I've had the best performance and longevity from those vinyl coated steel loop clamps I attempted to link earlier.

Caveat - please understand my TA's are merely added insurance, not intended for BIG power and/or rocking back & forth full time.

 

[bowlofsalad]

I'm not feeling the love with those. As you noticed the minimal adjustment range plus where does the TA attach?

I've had the best performance and longevity from those vinyl coated steel loop clamps I attempted to link earlier.

Caveat - please understand my TA's are merely added insurance, not intended for BIG power and/or rocking back & forth full time.

I am not sure what you mean by 'plus where does the TA attach?'. My guess is, how do you connect one of those round clamps to a torque arm? I've seen a video where they were opened up similar to a hose clamp, then you could slide it into whatever you wanted.

The loop clamps, can you tighten them around something? I don't just mean close the loop. I mean, can you make it so it gets smaller as you close the loop?

I am not really sure at what level of power are torque arms recommended on ebikes. I imagine on 36v and above, probably. I don't really know though, I have no frame of refrence for the amount of torque a 12v vs a 24v electric motor will generate on a dropout.

 

[pendragon8000]

Its the controller and motor and resistive force on the motor that determines power consumption and then efficiency of motor determines output power. Volts x amps =power in ... x efficiency=power out

A 6 fet controller (low power) on 24 v might be limited to 15amps so that's 360watts and at best efficiency about 288watts out. With good steel frame you might get away with no torque arms. Just nice tight axle nuts and the washers that have tabs that go into the dropout groove to stop rotation.

48v 20amp setup would need some sort of torque arm imo

 

[Ykick]

I am not sure what you mean by 'plus where does the TA attach?'. My guess is, how do you connect one of those round clamps to a torque arm? I've seen a video where they were opened up similar to a hose clamp, then you could slide it into whatever you wanted.

The loop clamps, can you tighten them around something? I don't just mean close the loop. I mean, can you make it so it gets smaller as you close the loop?

I am not really sure at what level of power are torque arms recommended on ebikes. I imagine on 36v and above, probably. I don't really know though, I have no frame of refrence for the amount of torque a 12v vs a 24v electric motor will generate on a dropout.

Most hose clamps sold with TA's can be opened and slipped through a slot in the arm. Those clamps you linked are the wrong shape to do that with a threaded nut.

Loop clamps must be sized accordingly but there's a bit of wiggle room with regard to the bolt hole and a person can always wrap a layer of tape or two under them to take up some slack. The vinyl coating not only provides some scratch protection but gives you a little cushion for snugging down.

As I said, any of these type TA's are merely insurance. Axle nuts are the real holding point. Run strong geared hub motors, high power 2kW DD hub motors and/or regen - clamping is the only method I'd consider.

Luckily, I don't need to bother with all that because I stay under 2kW and no regen with a 9C clone. Steel loop clamps work fine for that level of duty. And, they're cheap.

Those kickstand clamps are defintiely strongest but for what? 4kW DD with strong regen acting as a rear brake? No way....

Here's how I use them on a couple bikes I have here:

 

[bowlofsalad]

As I said, any of these type TA's are merely insurance. Axle nuts are the real holding point. Run strong geared hub motors, high power 2kW DD hub motors and/or regen - clamping is the only method I'd consider.

I don't think I understand this paragraph very well, especially what you mean by 'merely insurance', don't torque arms prevent the splaying and breaking of dropouts? My understanding is the arm on these torque arms enhances the torque arms ability to handle torque. In addition, the lever effect is said to help resist the twisting torque. I doubt I am capable of explaining this understanding, maybe I don't really understand torque arms at all. I imagine any sort of wiggle room in a torque arm setup to be destructive no matter how it's setup. If it isn't tight, the wiggle room would allow for a sort of kicking or hammering within the torque arm, at least that is what I've read. This is why I am so concerned with a very strong, tight fitting round clamp. No matter how strong or thick the material is, it is worthless without tightness going with it.

I am not sure I know what you mean by 'clamping method'. I hope to make plenty of use out of regenerative braking. One idea that seems to be suggested for regenerative braking is, (source:http://www.ebikes.ca/torque_arms/) "It can't be overstated how important it is in this case that the axle nuts are thoroughly tightened and that the torque arm plate fits tight on the axle to reduce the amount of 'wiggle room'. It is possible as well to use two torque arms, and preload one in the forwards and the other in the reverse direction." I am working on setting this up myself with two rev4 (from ebike.ca) torque arms, one facing up, and one facing down.