Disc rotor bolts

[Peter.Bridge]

Another question - what's the best thing to do when you are swapping over a disc rotor and the bolts from the original are too long for the motor wheel. I've used a 'rotor spacer' but are there slightly shorter bolts available ?

 

[saneagle]

Another question - what's the best thing to do when you are swapping over a disc rotor and the bolts from the original are too long for the motor wheel. I've used a 'rotor spacer' but are there slightly shorter bolts available ?

The screws normally come with the motor. They should be already in it, and they're the correct length for the motor. They put a plastic spacer underneath the heads, which is the thickness of a disc. You remove the spacer when you install the disc. Normal disc screws for bicycle hubs are too long. You can buy any M5 screws of any length you want. If you've lost your original ones, you need to measure the depth of the hole then add on a bit less than the thickness of the disc.

Pardon our interruption...

 

[saneagle]

The screws normally come with the motor. They should be already in it, and they're the correct length for the motor. They put a plastic spacer underneath the heads, which is the thickness of a disc. You remove the spacer when you install the disc. Normal disc screws for bicycle hubs are too long. You can buy any M5 screws of any length you want. If you've lost your original ones, you need to measure the depth of the hole then add on a bit less than the thickness of the disc.

Pardon our interruption...

If you put a spacer under the disc, the disc won't line up with the caliper. You normally need to put a washer on the axle that side to move the disc inboard. The spacer would move the disc outboard and make it worse unless you put it outside the disc, but then the screws will come loose because of the plastic.

 

[AndyBike]

Have you access to a bench grinder ? could take a bit off. But I would warn about making whatever you get(or grind) too short as it could be dangerous.

Also, buy yourself a tube of threadlocker - Blue.semi-permanent

Im on the other foot. My big bike rotors are 2.3mm(Hope HD solid)which need longer bolts anyway, but because I need to add a magnet two of them need to be even longer, which arent easy to find exactly, so i need to grind some even longer ones down to size.

But mind the threadlocker - its about a fiver and for heavens sake dont get the red, thats permanent and the allen head will possibly chew before getting those undone

 

[Peter.Bridge]

Thanks - the motor did come via the wheel builder but there were no bolts with it - The standard ones are M5*10, I have ordered M5 *8 round head allen via your link

 

[harrys]

Has anyone else had trouble with caliper screws that appear to be Torx head, but are not. Just crappy machining and neither a metric or Torx wrench can grab them.

 

[chris_n]

Has anyone else had trouble with caliper screws that appear to be Torx head, but are not. Just crappy machining and neither a metric or Torx wrench can grab them.

Splined? You probably need a special tool!

 

[Nealh]

There are some splined screw caps that have closer ratio finer spline then the wider spaced Torx , that said not come across them on push bikes.