Axle Spinout on bike stand

[Ethanator10000]

A while ago while I was working on my bike in the stand, I forgot to secure the torque arm before applying throttle to test it out. Being a grin all axle which requires a torque arm since it has no axle flats, it indeed spun out, wrapping the wire around the axle before eventually the wire either provided enough tension to allow the wheel to spin, or it wedged in between the frame and axle doing the same thing. Being in the stand, the unloaded motor would only be producing a tiny amount of torque. I looked at it carefully and I saw that I tore the outermost layer of heat shrink on the cable near the entry port, so I just tightly wrapped that spot in electrical tape. I couldn't see any of the wires beneath, or any bare metal.

This was a couple months ago and I've ridden like 500km no problem, but I have been wondering, is it possible that there's damage beneath? Is there any way to inspect without disassembling the motor? Or am I overthinking?

 

[neptronix]

..i'm surprised your motor still works, there must be some wire protection inside that most motors don't have.

 

[Ethanator10000]

..i'm surprised your motor still works, there must be some wire protection inside that most motors don't have.

Well the all axle is definitely well built, and the cable is pretty beefy. I think the fact that the cable also doesn't come out of the axle helps to allow the entire cable to coil up and wedge against the fork after a wrap instead of just twisting at axle helps too. Like I said, it was unloaded so it won't take a lot of torque to spin the wheel.. the QR pressure also applies some resistance to spin out so I don't think the wire was bearing a lot in this case.

I took off my electrical tape and really carefully inspected the cable again and I think this is just a case of me getting anxious, which happens a lot. The wires don't feel twisted, and the inner heatshrink isn't even scratched, which I think is a good sign?

 

[smitty2k1]

Looks better than when my torque arm came loose yesterday :-(

 

[Ethanator10000]

Looks better than when my torque arm came loose yesterday :-(

View attachment 354278

Oof.. sorry to see that. Mine seems to have just torn that outer layer of material there, but the harder inner black stuff isn't touched. Maybe I just got really lucky with how mine coiled up.

Luckily it seems to be fairly straightforwards to repair the all axle cable, just a bit time consuming as you need to unlace the hub from the rim. Best of luck.

 

[99t4]

I took off my electrical tape and really carefully inspected the cable again and I think this is just a case of me getting anxious, which happens a lot. The wires don't feel twisted, and the inner heatshrink isn't even scratched, which I think is a good sign?

Good sign yes. I would test it under high load and check for any localized wire high temperatures around the suspected problem areas.

 

[smitty2k1]

Oof.. sorry to see that. Mine seems to have just torn that outer layer of material there, but the harder inner black stuff isn't touched. Maybe I just got really lucky with how mine coiled up.

Luckily it seems to be fairly straightforwards to repair the all axle cable, just a bit time consuming as you need to unlace the hub from the rim. Best of luck.

I got some info from Grin, threading the new cable seems easy enough but like you said to open the motor you need to unlace it and it seems you also need some specific size presses and a puller, which I don't have. I just applied liquid electrical tape and bench tested everything and it seems fine for the time being. I may RMA to Grin later this summer when I go out of town for a while and won't need the bike. I don't have the time or tools to do the wheel build and motor disassembly.