How many have spun axles? Were you using a torque arm?

[zombiess]

I'm curious after some posts made in my previous thread. How many people have spun out their axles while using a torque arm? Front or rear? How much power?

When I talked to ebikes.ca about using a torque arm on my alum rear drop outs with a 48V 2806 setup they told me it was not necessary unless I want to start upping the power.

 

[Spacey]

Not spun an axle but my dérailleur snapped off where I had been using regen braking and the axle had been rocking back and forth, I now have a torque arm but there is still some play.

There needs to be no play at all really.

 

[Doctorbass]

6kW+ since 2007 ( speed above 100kmh, towed a schoolbuss with my X5)

Always had torque arm on both side

ZERO spun axcel

ZERO wheel fall off the bike

Dont ask if you need one or not... just consider it like the necessity of having a battery, motor or controller.. to me it's an integral part of the ebike kit.

Doc

 

[Drunkskunk]

Ebikes.ca is probably technicly right. you might not need a rear torque arm with a stock kit thats propperly installed and never abused. Maybe.

But that one time you miss fully tightening the rear nut after changing a flat or something, without a torque arm, you'll have a ruined motor, a destroyed bike frame, and probably a destroid controller. A torque arm is pretty cheap insurance.

 

[John in CR]

One axle spin first 10ft of first hub motor ride. Front mount on alloy forks, 2kw peak with a 500W torque model Grubee hubmotor. Dual homemade torque arms using 3mm stainless, through hole type. The torque arms turned the axle flats into 3mm wide circles like the axle was butter snapping the alloy dropouts like toothpics. Torque arms held the wheel on, so I was lucky and learned my lesson injury free.

For lower power like that I now use at least 6mm (1/4") steel per side with a snug fit to the axle, ie dropout or torque arm slots with a tap in fit or clamping type. For my higher power rigs I use 12mm (.5") steel on each side. All have a rough surface for a good bite with toothed nuts with no washers, just nut on dropout or torque arm. 2.5 years and over 10k miles, and not so much as a loose nut. All current and future builds will be clamping type, so I will have no reliance on axle nuts, because all bikes will have regen braking to minimize vehicle maintenance, which gets down to brake maintenance on a durable build. Regen brakes need no maintenance.

 

[zombiess]

I have one on each side, but in my other thread I had some telling me that this was not going to be enough to keep it from rotating with at 48V setup.

Trying to make sure I have my bases covered. Bike is going to be up and running this weekend... finally

 

[amberwolf]

See these posts:
http://www.endless-sphere.com/forums/viewtopic.php?p=352278#p352278
http://www.endless-sphere.com/forums/viewtopic.php?p=355453#p355453
also, about loose nuts.

A torque arm would have prevented the problem even without the axle nuts. So now it has one--a 10mm wrench. :wink:

 

[John in CR]

First time I've seen one of those types on the bike. It fits well and looks good. While you're probably fine with one on each side and a stock controller, I'd double them up on each side for piece of mind. It's quite probable that the axle is soft steel, and rightly so because the axle will then have some amount of give instead of snapping from a pothole impact or whatever. Once you look at the axle as soft, then imagine a crescent wrench as thin as those torque arms. Fit the skinny wrench tightly on the axle flats and put some pressure on the wrench, and you can easily visualize that the axle will deform allowing the wrench to turn. Torque arms aren't always made of hard steel either, so thin ones can deform in the same manner.

BTW, it's amps that are the concern, not voltage. Every motor has a torque constant that tells you how much torque for each amp of current regardless of voltage. More amps = more force exerted at the axle, and that force is literally thousands of pounds at the tiny radius of the hubmotor axle flats.

 

[dogman dan]

When using higher power, even proper torque arms can be inadequate. My first try at 72v 40 amps, I had two ebikes-ca torque arms on a cromo front fork. As I did a throttle test with the wheel off the ground, the axle still tried to leave the dropouts.

Cause of failure? Partly nuts still loose, even though I'd tightened them pretty hard. Partly the fact that the wheel was off the ground, adding a force tending to pull the axle down out of the dropouts. But primarily, a hose clamp is a joke for securing a torque arm for high power. The clamp simply started to slide down the fork. This is possible because the torque arms were a two piece design.

My solution was to weld a plate to the fork, allowing two bolts to secure the arm. Tested to 3500 watts and now rock solid. Nothing can rotate now, or slide down the fork.

Alternative solution, adjust the torque arm to fit your bike, then weld in place eliminating the pivot at the bolt of a two piece torque arm. Then secure with multiple hose clamps, or better still, a thick metal strap and bolt.

We need somebody to start marketing a torque plate kit. Basicly a nice thick lazer cut hole in the center of a peice about 4"x4", for rear hubs. The purchaser can then cut to the needed shape and angle for thier particular bike, using a cheap hacksaw or grinder.

Nothing wrong with offering a pinch type too.

 

[Spacey]

I'm thinking that I need to make a steel sleeve for my bike, it would be heavy but at least the axle wouldn't spin. Have no idea how to do it though.

This is what they were until I Steel Araldtite'd them in ...seems to be holding but there is a tiny bit of play in the actual torque arm.

 

[arkmundi]

Yep, and yes, using a torque arm. Lost the dropouts in the wreckage, but effected a repair that some may find useful.. See my MAC 10T, OSN A123 48V on Trek Shift 3 thread, along with a vid of some of the details.

 

[cj7hawk]

I didn't see the point even though I have aluminium dropouts, and even though someone pointed out to me that the damage is done because steel is harder than aluminium, I'm only putting out 200w or less, so perhaps it's not as important for my purpose, and I do check it regularly for any signs of damage ( none so far ). However I have heard of people snapping spanners, so I assume there's some significant shock involved also on higher power wheels.

I'm still not sure I'd use a torque arm though as I'm not impressed with a lot of what is being sold - I think if I was going to use something where the power did bother me, I'd seriously consider coating the dropouts with some HTS-2000 and remachining them ( that would also be a suitable repair if someone spun an axle and wanted to rebuild it ). I've seen small amounts of that stuff destroy carbide and steel tools when machining, so if brittleness is a problem and spanners keep on snapping, it seems a possible solution. It's also the only stuff I know of that could be used at home even without major tools, and sometimes I'd use it over my mig.

On the other hand, if you're going to use spanner for a torque arm, perhaps include a shock absorber...

David.

disclaimer - This may be a stupid idea.

 

[alfantastic]

I'm still not sure I'd use a torque arm though as I'm not impressed with a lot of what is being sold

I've used a couple of these on a 1500w rear hub build, and I was definitely impressed with the quality:

Cyclezee Torque Arms / Plates for Electric Bikes, E-bikes, Pedelecs

Don't know which ones you've been looking at, but I've had no issues, they're a snug fit, very chunky and available in two popular sizes.
I don't see the point of taking the risk of not using at least one torque arm, when they are as cheap as chips

 

[beast775]

My first ebike ride was a disaster.my front brushed 500w motor went flying,now i always use some type of torque arms over 250w.

 

[Ykick]

And for those who may not be readily aware - just like with hub motors, there's 2 common torque arm sizes. 12mm or 14mm, predominantly. Don't make the mistake a couple folks have made using a 14mm TA on 12mm motor axle.

As a lazy rider/builder, I also avoid regen with 2kW 2807 winding DD setup and consider TA's only as last line of defense. I'm even do aluminum rear but I make sure the axle fits deep into the dropouts and axle nuts properly tightened at all times.

OMT - many folks probably don't realize the majority of controllers will have some form of regen enabled. This is hard to tell until you see your CA DP light up when coasting without a battery connected to the system. There's varying levels which can be programmed within some of the more advanced controllers but unless you're using a serious "clamping/pinching" TA design, my advice is merely to STAY AWAY from regen.

 

[docnjoj]

My first experience with my homebuilt trike using steel rear triangle from a Goodwill BMX spun my geared motor and destroyed the wires. Torque arms on everything since. I will not use alloy for frames! 2 torque arms on front steel for wifes USX and one torque arm on my steel Steintrike rear. So far (about 7 years) so good. Always use torque arms on geared motors or if using regen or both. Always use steel for front or rear forks. Period.
otherDoc

 

[docnjoj]

For torque arms I use Miguraliart (sp?) or other similar ones. I would use the DrBass ones if I could weld them on. I can since my grandson is now a welder. My welding sucks.The ebike.ca ones look OK.
otherDoc

 

[docnjoj]

Oh yeah one more thing. For high power use Johns method of plate plus a threaded fastener to compress the steel. Forget about alloy. Use a mid-drive.
otherDoc (again)

 

[adriftatsea]

For those wanting >5k watts, I'd echo that using an aluminum frame is probably a bad idea.

I have a HT3540 and the good doctors dropouts, but my underlying dropouts weren't really up the task. Pretty much all aluminum hardtail or front forks don't have enough surface material for epoxy bonding or enough mass for securing it with bolts. From now on I'll only be using steel/chromoly dropouts that clamp a 14mm axle. (oh, and moving to mid-drive for a while...)

 

[fellow]

Can someone post pictures of the most popular/sexy torque arms and where to buy those as of 2015? I'm looking for a rear torque arm that I can bolt into disc brake holes on one side, and screw in on another side...something removable, stealthy/hidden.

 

[arkmundi]

google images torque arm ... this is the sexiest torque arm I could find .... :lol:

 

[fellow]

Oh, that looks like Dr. Josef Mengele's favorite piece of steel. This one looks nice:

 

[Cyclezee]

I'm still not sure I'd use a torque arm though as I'm not impressed with a lot of what is being sold

I've used a couple of these on a 1500w rear hub build, and I was definitely impressed with the quality:

Cyclezee Torque Arms / Plates for Electric Bikes, E-bikes, Pedelecs

Don't know which ones you've been looking at, but I've had no issues, they're a snug fit, very chunky and available in two popular sizes.
I don't see the point of taking the risk of not using at least one torque arm, when they are as cheap as chips

Thank you for your comments Al :wink: