TBH I've made some really half ass torque arms for my ebikes with 1/4" x 1" x 5" flat steel from HD/Lowes and took an angle grinder to it. No matter what, they would always work. Some of the worser(sp?) t.a.'s would always work, with an ever so slight angular movement of the axle. My old blue Townie Electra was a good example, after a few t.a.s cut with the worse one on that bike, the actual dropout of the bicycle where the bicycle wheel slides onto the frame, the aluminum of the flats on the dropout really wasnt that bad. Mind you I wasnt using much power, I'd say 1500W.
Making a notch for the hose clamps and a notch for the axle to sit in.
The axle notches were never very accurate but they were close enough. Sometimes only half the notch would fit snug, the notch would have been 2cm deep and the width is whatever the axle width is.
I always found it better to use a wider cut off wheel but only did that once in my half dozen pairs of t.a.
but my grinder would always have a thin blade so thats what I'd use.
I'd cut the two sides (where the axle flats snug up on) and try to grind away between them with V cuts, angle cuts to clear out the middle.
I'd always cut the axle width to short having to use the side of the cutoff wheel to widen ever so slightly. And often just seeing if the steel would go in all the way. Mind you the third surface was really bumpy from the cutoff wheels (aside from the sides and open end)
Half the time I'd scribe using a caliper, other half a ruler. It'd always be to short.
My test to see angular movement of axle under power, would simulate by using an adjustable wrench, on the axle flats and see how much movement there was of the axle. If it seemed like yeah sure it was aight, done deal and ride. Even with movement, and 3 or 4 of them always had some slight movement. But like I said the frames dropout flats werent that bad, I could probably even literally take a picture for you if you'd like of the frames d.o.'s. The movement, would be adjustable wrench with handle 4-5" would be 1-2cm at the end of the wrench. For all the technical peeps out there in ES world.
