I was recently looking at some new front rotors for my ZXR250 as I know there is a direction arrow on them. I was checking to see which side it was for; LHS vs RHS. Looking at the rotor I realised it was a mirror image of the rotor for the other side, which made me think why are rotors marked with direction arrows? I understand why tyres are and maybe even rims, but rotors? I asked a forum member and I got the reply... "A direction arrow on rotors is due to the mount design. Braketech being an obvious example" I completely understand in the case where the rotor has an 'asymmetrical' design, but in the case of my ZXR rotors, they look identical and if I removed the direction arrow you couldn't tell one side from the other. I can't think of a good reason why there is a direction arrow on my rotor? Pads - no; material - no; buttons - no; offset - no. The only reason I could find online was with regards to vented rotors where the vent grooves are directional, so doesn't help me as my rotors don't have venting grooves. I might have to contact Metalgear (where the rotors came from) and ask them.
Okay, a bit of an update, which makes some sense... The direction arrow, in all cases where symmetrical rotors are used, is for maintenance. When the rotor is removed and then needs to be reinstalled (for whatever reason), it needs to go on the same side it came off due to wearing on the rotor from the pads. Changing pads should have the same wear profile on the rotor. Not sure about that fact, but there you go.
