Rear hub motor, what nuts to use on 12x1.25mm thread?

[Samd]

Gday there,
bought a cheap 350W geared rear bafang or clone and have had it laced into a good solid rim. But I just noticed it doesn't have any rear nuts!

Used my thread measurer - it matches M12x1.25. If I go down to the local nut and bolt shop should I just buy mild steel nuts, or stainless, flanged or otherwise? I won't be taking the bike past about 700watts and the dropouts are dead vertical, so in the worst situation it should stay put due to my body weight pushing down on the dropouts/axle.

Thanks in advance. Whilst I have some electrical and mechanical knowledge, my bike knowledge is nought. Checked Sheldon Brown etc but no joy there....

 

[motomech]

The ones that should have come with the motor would have been flanged with a serrated mating surface. You probably won't find those so use some Nylocs.
Did it come with the washers, If the Bafang used the same set-up as my mini's, there should be a pair of torque washers and a pair of flat washers.
If the torque washers are not there, link my build thread where I have a photo of what they look like and where they go. They are important.

 

[Punx0r]

IIRC 12x1.25 is standard size for bicycle axles? Any bike shop should have the correct flanged nuts

 

[Chalo]

Gday there,
bought a cheap 350W geared rear bafang or clone and have had it laced into a good solid rim. But I just noticed it doesn't have any rear nuts!

Used my thread measurer - it matches M12x1.25. If I go down to the local nut and bolt shop should I just buy mild steel nuts, or stainless, flanged or otherwise? I won't be taking the bike past about 700watts and the dropouts are dead vertical, so in the worst situation it should stay put due to my body weight pushing down on the dropouts/axle.

Thanks in advance. Whilst I have some electrical and mechanical knowledge, my bike knowledge is nought. Checked Sheldon Brown etc but no joy there....

You'll need metric fine thread. Normal M12 nuts are 12 x 1.75, and just to make things interesting, there are also 12 x 1.5 and 12 x 1.0 flavors to choose from. You don't want those.

If you can't get what you need at a fastener place, try McMaster-Carr. http://www.mcmaster.com/#metric-fine-thread-nuts/

For what it's worth, you may be better off furnishing your own nuts, rather than using the incredibly crappy hardware that comes with a typical Chinese motor kit.

I'd use normal class 8 nuts, which are the counterpart to 8.8 bolts. In truth, it probably doesn't matter what grade nut you use because the axle is probably grade negative 3.

Chalo

 

[Chalo]

IIRC 12x1.25 is standard size for bicycle axles? Any bike shop should have the correct flanged nuts

No. 10 x 1.0 is normal, and 14 x 1.0 is generally available. Nothing in between is standard, and the only 12mm axles I know of are M/C type through axles for downhill bikes.

I have never come across a true 12mm nut, any pitch, in a bike shop.

 

[Punx0r]

My apologies, I could have sworn I'd seen some that size in a bike shop!