Strongest clamp for torque arm?

[Ykick]

My clamps do not wiggle, that was a figure of speech (wiggle room) about snugging the loop clamp around whatever part of the bike you wish to attach it. I worry more about the common hose clamps that often snap when tightening them against the sharp, hard stainless steel slot in most TA's.

I wouldn't trust anything except a "clamping torque arm" for significant regen duty. I found regen to be a waste of time and resources for my application.

Since I also use one of those thin AmpedBike TA's there's no way I ever want more than emergency assisting force applied to the motor axle. Insurance only. IMO nothing more is really needed when you remain within the performance scope of a bicycle.

 

[bowlofsalad]

I wouldn't trust anything except a "clamping torque arm" for significant regen duty. I found regen to be a waste of time and resources for my application.

What qualifies as significant regen duty? Why would ebrakes be a waste? If you don't use ebrakes, what do you use in it's place? Surely pulling the brake lever turns the motor off on your bike? Some people say regenerative braking is a waste of time in terms of range gain. Even if it only added 1%, I'd be fine with that. Part or maybe more of ebrakes appeal is it's another set of brakes. I don't have the luxury of disc brakes, so more potent and more reliable braking (v brakes can slip when wet or muddy) power doesn't sound unappealing to myself.
I know some controllers have the option of determining how strong or weak the regenerative braking applies itself. I know this is an applicable idea within the magic pie controller. https://www.google.com/search?q=magic+pie+regenerative+braking&source=lnms&tbm=isch&sa=X&ei=MaZ9UeeyMoeirgG4zoCAAg&ved=0CAcQ_AUoAQ&biw=960&bih=444#imgrc=3AKScBBh4im9OM%3A%3Bis6Kt2Hn63SL6M%3Bhttps%253A%252F%252Fwww.veloverde.net%252Fimages%252FPI-200%252520GUI.jpg%3Bhttp%253A%252F%252Fwww.veloverde.net%252Findex.php%253Fdispatch%253Dproducts.view%2526product_id%253D29863%3B688%3B571
I am a total newbie in the ebike world. Forgive my barrage of endless ignorance.

 

[frogblender]

Behold, a torque arm made from 3/16" mild steel, CNC milled.

- the TA fits "nice-and-snug" over crystalyte's axel - it is not "super-tight", and there is a hint of slop. If you "pre-torque" the axle against the TA (described below), the slop is moot.
- No hose clamps. Instead, I drilled and tapped a hole in the frame for a #10-32 screw (the screw at the top). Once this screw is tightened, the TA itself does not budge.
- Since the frame had no holes for fender attachment, for convenience my torque arm includes a tapped 10-32 hole near the axle.
- the extra through-hole beside the convenience hole was to hold down the part during machining.
- the TA is small and light.

Errors I made:
- I erroneously chamfered the axle cutout .010" - this removes material right where it is needed the most. I should've just left the edges sharp.
- I should've "pre-torqued" the axle against the torque arm, to make the slop irrelevant (tighten the #10 screw, then grab the axle with a wrench, and, while torquing the axle backwards against the TA, tighten the axle nuts). (this would take me all of 90 seconds right now, but I'm felling lazy).

My assumptions:
- regen seems to only draw less than 10Amps. Full throttle forward current limit is 35A (soon to be 40A once I get my new 48v 20Ahr lifepo4). So I figure regen torque is only 25% of forward torque, and not worth worrying about - thus, I will pre-torque the axle against the forward torque.

- a torque arm on one side only is good enough (I actually ran with NO torque arm, at 35A, for about 30km, with no problem - so I figure one TA is enough). I chose the side where the axle is stronger (ie. the side where the axle is not butchered to allow the motor wires).

- extra-long TA's are not needed. In my case, the TA's moment arm is just under 2".

I was lucky enough that the bike's subframe around the rear axle was (almost) flat, so my TA could be a simple 2D shape.

Hose clamps are generally bush-league: Often they allow some movement under load, which is not good. And they look ugly. And they have lots of sharp edges to hack up an ankle.

 

[pendragon8000]

My assumptions:
- regen seems to only draw less than 10Amps. Full throttle forward current limit is 35A (soon to be 40A once I get my new 48v 20Ahr lifepo4). So I figure regen torque is only 25% of forward torque, and not worth worrying about - thus, I will pre-torque the axle against the forward torque.

I've been thinking about this to. My understanding is that the controller short circuits the windings and the pulse of current when it is released is pwm to the battery. This is done at very high frequency. I could be wrong.
Anyway this is very inefficient therefore its not proportional to the way the wheel is powered. My motor gets really hot when I use regen , that's where allot of the energy goes, not through the controller to battery.

 

[sal_park]

I've just skimmed through the responses here and no one (that I could see) talks about the fact that depending on how you install the TA the clamp will be in compression or tension. I agree that a jubilee clip would not be a good idea if it was put into tension under load, however if it was in compression (and hence the force would go from the TA to the frame/fork directly) I can't see an issue* with using one.


sp


* as in it will work. Sure, it'll still be ugly and have sharp edges etc.

 

[pendragon8000]

I've just skimmed through the responses here and no one (that I could see) talks about the fact that depending on how you install the TA the clamp will be in compression or tension. I agree that a jubilee clip would not be a good idea if it was put into tension under load, however if it was in compression (and hence the force would go from the TA to the frame/fork directly) I can't see an issue* with using one.


sp


* as in it will work. Sure, it'll still be ugly and have sharp edges etc.

good ponit, i just assume acceleration torque presses arm into frame is the best/only way to go.

 

[bowlofsalad]

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.

Why would C washers be more important than a torque arm? I thought c washers only purpose was creating gaps so you could fit wider wheels in between dropouts.

How would you accurately make the drop out deeper? The use of a file comes to mind, one spaced exactly as wide as the dropout.

Is there another name for builders plate?

 

[llile]

Forget torque arms. Clamping is the way to go if you are using a beefy motor, IMHO. This is a custom weldment that engages the flats of the motor bolt, and squeezes them between two flat surfaces that are as large as is allowed by the dropout geometry. One end is welded onto your dropout, a horizontal flat item. The other side is a loose flat piece. Two holes are drilled and tapped into the stationary piece, and two mating (larger) holes are drilled into the loose piece so that a hefty hex head bolt can squeeze the two sides together around your axle.

I have attached a pic of mine, however the whole thing is a custom weldment on a trike, so large parts of the pic are Not Applicable. It is all beefy - I think 10mm bolts and 1/4" steel for the clamps. Credit John Robert JRH for showing me this detail.

 

[bowlofsalad]

You most be generating some serious torque to warrant that setup. I definitely prefer over kill, but I don't know if my setup would need that much. 48v30a lowest winding em3ev has available direct drive hub. You must have extremely high voltage, close to 100 maybe?

Part of the issue that I've had with the clamp setup is my drop outs are vertical. I don't really know what I would attach a torque arm such as yours to. In the end, it all seems to boil down to the need to attach something to the frame, either via glue, welding, drilled holes or some form of a clamp.

I decided to measure the thickness of a dime with some digital calipers, the dime measured .05". So I figure I'll just round up and maybe get some 16ga steel sheet (.063).

 

[bowlofsalad]

I learned that there is a way to adjust the intensity of the regenerative braking. The way it is now is way too intense. The settings for ebrake intensity are under 'EBS level' in the controller program. 0 = weakest, 2 = strongest for the settings. Mine is currently at 2, I think I'll set it to 0 and see how I feel about it.
Going down a hill yesterday, really my first hill on an ebike, I barely squeezed the brakes thinking I'd prepare to come to a stop at the sign at the end of the hill. If there had been any sand, oil, wetness or anything like that, the wheel very likely would have skid based on how hard it felt like it was stopping me, pretty intense.

I wonder if anyone has a laid out explanation of what all these settings do in controller software.

The reason I bring this up is because of what 'frogblender' said. I suspect plenty of people have different settings for their regenerative braking without really realizing it.

 

[Ykick]

I learned that there is a way to adjust the intensity of the regenerative braking. The way it is now is way too intense. The settings for ebrake intensity are under 'EBS level' in the controller program. 0 = weakest, 2 = strongest for the settings. Mine is currently at 2, I think I'll set it to 0 and see how I feel about it.
Going down a hill yesterday, really my first hill on an ebike, I barely squeezed the brakes thinking I'd prepare to come to a stop at the sign at the end of the hill. If there had been any sand, oil, wetness or anything like that, the wheel very likely would have skid based on how hard it felt like it was stopping me, pretty intense.

I wonder if anyone has a laid out explanation of what all these settings do in controller software.

The reason I bring this up is because of what 'frogblender' said. I suspect plenty of people have different settings for their regenerative braking without really realizing it.

And many of those folks believe DD hub motors cog too much, LOL....

Do what you need to do but regen ain't worth it for me by the time I factor all the other BS required to do it properly and safely for dropouts in addition to the switching and program setup. Even then, what's to prevent those Chinese soft axles from twisting into two pieces? I don't have a press and metal lathe at my disposal...

I don't like regular stainless hose clamps for reason previously described - too much chance of cutting and damaging them while tightening against the sharp edges of most TA's.

Bolted loop steel clamp is my simple, secure way for the worst case, which I hope never happens - but it's there if it does.

 

[WhatcomRider]

I secured my Grin Tech front torque arms with insulated clamps that I found in the electrical section of the local hardware store. By filing the torque arm slots a bit, I was able to force both ends of the clamps through the slots.

Two 1" clamps fit perfectly on the right side:


A 1-1/2" clamp, shortened and redrilled to maybe 1-1/4", fits nicely on the left side.


I feel very confident that the AL dropouts will hold up at 25 amps pushed through the motor.

 

[dogman dan]

The alloy dropouts won't hold squat. But you do look to have a properly installed torque arm that will hold some force, including a good substitute for the hose clamp.

Keep those nuts tight anyway though. The fork destruction tests showed that nut pressure alone was able to provide a lot of the resistance to rotation.

Note, Grin's design does allow for the use of two hose clamps in the design. Your forks may or may not allow using two. It would be really easy to fabricate a new second piece to the torque arm, allowing the use of multiple hose clamps. Or, in your case, a home made second piece could bolt to both of the disk brake mounts.

 

[WhatcomRider]

The alloy dropouts won't hold squat. But you do look to have a properly installed torque arm that will hold some force, including a good substitute for the hose clamp.

Keep those nuts tight anyway though. The fork destruction tests showed that nut pressure alone was able to provide a lot of the resistance to rotation.

Note, Grin's design does allow for the use of two hose clamps in the design. Your forks may or may not allow using two. It would be really easy to fabricate a new second piece to the torque arm, allowing the use of multiple hose clamps. Or, in your case, a home made second piece could bolt to both of the disk brake mounts.

Thanks for the comments. The bolts that come with the torque arms are high grade SS with fine threads so that they can be tightened very tight, which I made sure to do.

 

[dogman dan]

I was referring to the axle nut. Sorry if I stated that unclear. Even the best non clamping torque arms are prone to rounding out the axle itself if the nut gets loose.

A tight nut helps resist that rocking back and forth, that grinds away at the corners of the axle flats.

 

[bowlofsalad]

When I heard about nord lock washers, I was pretty much instantly sold. I've checked the tightness of the nuts many times, still nothing loose with the nord lock washers, but I will continue to check them. Although it seemed pretty important to keep the nuts tight, that thread started by Justin (ebikes.ca) really made it clear how important it is.

 

[EdwardNY]

I used a regular hose clamp, the type you can buy in a hardware store and it was always coming loose. I would have to re tighten it down after every ride.

I was looking through McMaster for something a bit better and saw a clamp called "Vibration Resistant Hose clamp". Seemed to be what I needed as vibration from riding was my problem. They say they are for high torque applications, so what we need.

The clamps looked thicker and stronger then a regular hose clamp and they did their job of staying tight and so far with heavy off-road use, the clamp never needed to be re-tightened. I still check them every ride but they are always tight.

http://www.mcmaster.com/#standard-hose-clamps/=nku5ut

If you are stuck with hose clamps and want something that will not loosen up with vibration, then I would recommend these. Don't use cheap hardware store ones.