RM G062.750/1000.DC Rear Axle Bolt Torque Specs?

[Studie]

Hi Everyone,

I happen to have an Aluminum bike frame that goes with the G062 1000W rear hub motor. I was riding the other day and the rear motor came loose.
Any idea what torque it should be tightened to? I've used my torque gun but nothing, so I used my torque wrench and tightened to 50ft/lbs. Is that too much for an aluminum bike frame?
I also read about something on the internet about nordlock? Or something like a washer?

Please advise!

 

[yam_sammy]

I happen to have an Aluminum bike frame that goes with the G062 1000W rear hub motor. I was riding the other day and the rear motor came loose. snaptube vidmate
Any idea what torque it should be tightened to? I've used my torque gun but nothing, so I used my torque wrench and tightened to 50ft/lbs. Is that too much for an aluminum bike frame?
I also read about something on the internet about nordlock? Or something like a washer?

I think this is too much for an aluminum bike yeah tray to get it down

 

[AHicks]

Is your bike equipped with torque arms on at least one side? If not, installing at least one of those might help reduce the required torque to hold the axle in place.

 

[harryS]

I researched this a month ago. I recall I found a RAD posting that said 25 ft-lbs, and that's what I use. Seems light, but when I did it with a clicker torque wrench, it was heavier than what I've done by feel to my various ebikes.

I had also used 50 ft-lbs on a front motor bike (steel fork), but it did seem too tight. These are M12-1.25 threads, but it is threaded for less than half of the surface because they cut the axles to be 10x12.

 

[AHicks]

Is that what torque arm is for?

I thought torque arm was for preventing from motor destroying the frame. (particularly dropout area)

Yes, exactly. You could think of it as torque arm(s) killing 2 birds with one stone. They help resist (or prevent) the tendency of the axle to squirm/twist in each direction under power, tearing up the drop out. By doing that, they reduce the torque on the axle nuts necessary to prevent that if you were trying to get away without them.

 

[harryS]

I also should note that I have torque or torque plates on all my motors with that 25 ft-lbs, except for the store bought Ecotric which is just a alloy frame.

Justin Grin of Grin Ebikes went thru a whole study of this while developing his torque arm. He found that without a torque arm, you only got minimal axle retention force by going past 30 ft-lbs, but it jumped to a higher level once he put in a torque arm. It's a very long read, but the main info in the first few pages.

Dropout Failure Experiments, and a call for Fork Donations

The strength of bicycle forks, their ability to handle the torque of hub motor axles, and the importance or non-importance of torque arms, has been a heavily debated topic in the ebike community. And rightly so, since failures that result in a wheel falling out of a vehicle can be more than a...

endless-sphere.com

So I think I'll crank my Ecotric up to 30 ft-pounds.