what's the proper way to install torque arms?

ClintBX · May 15, 2017

Hi EPFMs,

I have a question about installing torque arms.

I just bought a $25 torque arm from ebay and I've installed the way that my common sense tells me but I'm not certain if this is done right.

I have a rear hub motor and I've put it on the non gear side of the hub.

My motor is a 1200 watt and I've ordered a second torque arm for added reinforcements. Doing the chain side will be a little trickier.

aroundqube · May 15, 2017

http://www.ebikes.ca/product-info/torque-arms.html

amberwolf · May 15, 2017

you might check out the "torque arm picture thread"

some info in a few of these threads; sorry i couldn't find a search that narrowed down to just the relevant ones

https://endless-sphere.com/forums/search.php?keywords=proper*+install*+torque+arm*&terms=all&author=&sc=1&sf=titleonly&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

https://endless-sphere.com/forums/search.php?keywords=proper*+install*+torque+arm*&terms=all&author=&sc=1&sf=firstpost&sk=t&sd=d&sr=topics&st=0&ch=300&t=0&submit=Search

motomech · May 15, 2017

On the chain side of my geared motor install, I was unable to fit all or part of the "genaric" style torque arm so I went with the V4 TR from Grin(Ebike CA);

Somewhat pricey and smaller overall than I anticipated, it was never the less, a bolt-on solution that overwise, would have required a custom TA.

http://www.ebikes.ca/shop/electric-bicycle-parts/torque-arms/torqarm-v4.html

zukster · May 15, 2017

That looks fine. Just make sure the little bolt that holds the two pieces of the torque arms together is done up tight, to prevent the twisting.

miuan · May 16, 2017

I see that little bolt taking too much torque. Adding a second hose clamp would certainly help.

rojitor · May 16, 2017

I wouldn't go without 2 torque arms . Always 2. Just make sure the metal is thick enough and the hub does not move at all and you will be fine. Cheap torque arms tend to twist over time so high quality metal is a good investment.

docw009 · May 16, 2017

Am I correct for thinking that the normal turning force on the axle will be clockwise, opposite the wheel rotation? If not correct, then ignore the next comments.

That will be the same direction for the first arm. so it's a matter of looking how it is constrained. In the first picture, isn't it mostly pulling the second arm parallel to the bicycle frame? So the second arm has to be clamped down hard enough to resist a sliding motion?

dogman dan · May 16, 2017

What you did is exactly right for your particular frame.

To make the install truly bombproof though, adjust the arm to the right angle, then have it tack welded so it can't swivel at the pivot anymore.

Two of them as you have it, with the bolt good and tight will do fine though.

zukster · May 16, 2017

dogman dan said:
What you did is exactly right for your particular frame. then have it tack welded so it can't swivel at the pivot anymore.

That is a really good idea. What I did is upgrade the hardware to metric 12.9 which is about the same as imperial grade 8.

Canadian Tire sells metric Hillman Class 12.9 Socket Cap Screws(really they are bolts) that are perfect for this sort of thing. With lower grade hardware, I snapped a few of the bolt when tightening.

ClintBX · May 17, 2017

Alright! Thanks guys. It's reassuring to know its on right.

I just received the second torque arm. I'll be installing that soon. It might have to go on a little differently though because of the gears.

electricwheels.de · May 21, 2017

.
here some torque arms mounted on my Surly ICT AWD:

.

what's the proper way to install torque arms?

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