Torque arm thick enough ?

Hi Guys,

Before i clean this torque arm up any further im wondering if you think its strong enough ?

I will be running a MXUS 1000W 48v xf40c rear hub motor. 48v battery, 13ah battery.

The torque arm is made of 10mm stainless. The axle should sit right at the bottom of the cutout. I wasnt planning on putting a clamp bolt on the end but the more I look at it the more i worry. The opposite side will be made of the same 10mm stainless.

I would say that is more than enough for only a 1000w hub, but it never hurts to be thick. I would, however, put one on each side though like you say.

Holy crap dude that TA is thicccc.... What kind of dropouts are your bike? Alu? Shoot I'm running close to 2000w and I dont have torque arms on my steel frame trek 800.... Im planning on some and I've got the metal...just haven't got around to it.

That's probably fine, but it would be stronger even with thinner material if it had a closed eye for the axle. Consider a normal double-ended wrench. The ring end is much less massive than the open end, but it still takes more torque.

Unscrewing your caliper bolts is no big deal compared to dealing with the axle nuts, so what's the harm?

Looks strong to me especially considering I ran 52V through a 30 amp controller ("1000w, 48V" motor) for three years in a Tidal Wave aluminum frame with no torque arms. Admittedly, I didn't have regen.

Justin's testing showed that how tightly you torque your axle bolts is a big factor in torque arm effectiveness. So I would definitely clamp the axle onto your torque arm. Though I wonder if your axle is even long enough to fit a nut beyond the torque arm.. Also, in your situation you have a big air gap between the torque arm and the dropout. So you'd have to put a spacer or some washer in that gap.

But to your original question, sure - its plenty thick - which is probably good since it is open ended and you may not be able to clamp the axle to it.

In short, this is a somewhat unconventional design (gap, no clamp, thick, only one arm). So it's hard to be sure how it will perform if you don't clamp the whole assembly together in on big sandwich. If you clamp it all together I'm sure it will be fine. Also, a closed hole is probably better and I'd prefer using two thinner (6mm or so) torque arms - one on each side.

I think I misunderstood what you meant by "clamp bolt." If by clamp bolt you meant that the torque arm dropout would pinch or clamp the axle (connecting/squeezing the open ends), then yes, I think this would be plenty strong and I would do that.

Its plenty, though still open. But if your nut does somehow loosen, and the axle starts to lever itself out of the notch, at that point it might start bending.


You absolutely positively will need a spacer washer that perfectly fits that gap between TA and dropout. Tighten it without one, and you will crack your brake mounts right off the frame.

If you ever go high power, like more than 2000w, its a great idea to do some form of clamping dropout.

Thank you guys - Yep there is definitely going to be a few spacers going in spots as there are a few gaps. Just quickly bolted in on for the pics without spacers.

I have yet to make the other side, that's next & yes they will all be clamped together as a sandwich.