Electric Bikes Conversion Kits EMTBS eRoad/Commuting What's New?

Torque arm

M

mike killay

Esteemed Pedelecer
Feb 17, 2011
3,012
1,629
I am thinking of putting a hub motor in my old bike for my son.
Looking at the adverts, they all seem to rely on special nuts in the drop out to stop the axle turning backwards. This does not seem a good idea to me.
Now and again, posters refer to torque arms but I have never seen a picture of one. Further, many hub motors do not seem to have any external structure to which one could be fitted.
Can anyone please clarify?

Mike
 
flecc

flecc

Member
Oct 25, 2006
53,265
30,652
They use the flats on the spindle to prevent rotation Mike, the hole in the arm having flats on the sides to match. Front motor ones are mostly long thin arms that clip to the fork leg, rear can be shorter like this one:

antitorqueplate.jpg
 
D

Deleted member 4366

Guest
If you stick with a 250w motor, you don't need torque arms. Most motors come with anti-rotation washers that fit in the drop-outs, which are sufficient to resist the torque provided that the nuts are always done up tight. I've run a 40amp 48v rear motor with only the anti-rotation washers and nothing broke - but I wouldn't advise it's long-term use like that. Once you go for the bigger 350 and/500w front motors, torque arms are necessary, especially if you have magnesium fork because of their tendency for metal fatigue (cracks ad then sudden failure at some time in the future).
 
S

Scottyf

Esteemed Pedelecer
Feb 2, 2011
1,403
-1
Ideally two would be better than one.
I use two as the axel length allows me to. I also run two anti rotation washers that come with the motor.

I got mine from Catsnapper on here for £13 for the pair delivered.
 
C

Cyclezee

Guest
eZee conversion kits come supplied with torque plates as shown in the photos below.
When bought seperately from Cyclezee they are normally £5 per set, but until new stocks arrive, they are only supplied with a complete conversion kit.
image[1].jpgTorque Arms.jpg
 
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C

Cyclezee

Guest
Here is another photo showing a complete set fitted to a fork leg of our demo bike with a 'P' clip.
Fitting both arms was not necessary in this instance, the photo is is only to illustrate a complete torque plate kit.

BMC12.jpg
 
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A

aseb

Esteemed Pedelecer
Dec 12, 2009
269
0
front or rear wheel drive? They are different.
Aluminium or steel frame? Power of motor? More needed with aluminium than steel at legal power levels, but I'd recommend them either way whatever the power, and one either side if using a few kilowatts of power.

I like the ebikes.ca torque arms (see amigafans post) but they also have a rear wheel torque arm as well as those 2 front wheel ones.
 
C

Cyclezee

Guest
aseb said:
front or rear wheel drive? They are different.
Aluminium or steel frame? Power of motor? More needed with aluminium than steel at legal power levels, but I'd recommend them either way whatever the power, and one either side if using a few kilowatts of power.

I like the ebikes.ca torque arms (see amigafans post) but they also have a rear wheel torque arm as well as those 2 front wheel ones.
Click to expand...
Hi aseb,
I'm not sure if your questions are directed to me or not, but I recommend torque arms/plates for all kit installations, front or rear, aluminium or steel frames. The eZee type really inexpensive.

I will be meeting Justin Lemire-Elmore of ebikes.ca when I travel to the eZee factory in Shanghai next month and will discuss getting a supply of their Canadian manufactured torque arms if there is enough demand in Europe.
 
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