One Torque Arm or Two?

[rogerc]

I got notice my kit is on the way from Cellman at EM3. I only ordered on troque arm for the rear mount motor.
I am putting it on a Giant Revel with alum frame.
Got the Mac 10t motor.
Is it mandatory that I use two torque arms or will one handle the job?

 

[kudos]

Most only use one..

Two for high power applications.

Or none if you use a steel frame and relatively low power.

I've been running a Mac 10T with one TA for nearly two years just fine.

Kudos

 

[iperov]

AGAIN ? http://endless-sphere.com/forums/viewtopic.php?f=2&t=53467

 

[dogman dan]

Always again from the noobs. It's just how it is. Type torque arm in the search, and you get a billion pages to look at.

One is plenty for most stock hubmotors. Two if you have a controller over 30 amps would be my recommendation, OR a very superior design using one. For example, my high power bike has just one, but it's a very strong pinching type torque control device.

 

[Ykick]

Generally speaking, geared or DD, one TA is probably enough for sub 2kW motors. One thing not often mentioned is that many rear derailers reinforce RH dropouts with their hardened steel or in some cases, Titantium attachment bracket.

While it won't prevent an axle from "walking out" of the slot due to loose nuts it will significantly reinforce the axle slot on the RH side.

Therefore, with a single TA I'd suggest installing it on the LH side, keep nuts tight, you should be good to roll many, many miles.....

 

[rogerc]

Great info guys.
Really appreciate the advice and how to's.
RC

 

[Drunkskunk]

Generally speaking, geared or DD, one TA is probably enough for sub 2kW motors. One thing not often mentioned is that many rear derailers reinforce RH dropouts with their hardened steel or in some cases, Titantium attachment bracket.
.....

I'm not sure which bikes you've seen this on. Generaly the replaceable derailer hanger is made of a softer metal than the frame. it's designed to bend in case of a wreck, so that the frame isn't damaged. Sort of a frame fuse.

As for the torque arms, Two is better, but with a good one, only one may be needed. However, if you plan to ride offroad much, get a second torque arm.

 

[spisska]

One is most likely enough, just as on a car a brake on two wheels is usually all you need.

But there is something important to consider: If your wheel falls off at 20+ mph, will you think yourself wise for saving $40?

 

[Ykick]

I'm not sure which bikes you've seen this on. Generaly the replaceable derailer hanger is made of a softer metal than the frame. it's designed to bend in case of a wreck, so that the frame isn't damaged. Sort of a frame fuse.

Could be, I'm not a bicycle expert. But it sure seemed hard steel by virtue of a file than the aluminum dropouts it slides over.


My other "better" bike appears to be alloy but extremely hard thus ASSumed Ti22? We all know how that ASSuming thing works out....

 

[Ypedal]

My norco Chaos has a very strong insert that fits into the aluminum dropouts and acts as a derailleur mount at the same time..... but on another bike ( Wall mart special ) .. cheap stamped soft steel over the dropout to drop the derailleur lower in relation to the axle.. that thing is total crap.

so it varies.

below 40 amps , 1 torque arm is fine.

60+ amps, depending on voltage..... more is always better.

 

[dogman dan]

Yeah, that's the point where some just twist axles in half if the TA holds.

One typical TA, even some of the cheaper ones is plenty for 48v 20 amps. Around 1000-1200w. Above that I use two, or one pinch type device.