i've got a Cotic Roadrat, and the disc mount on the fork is on the right hand side (as you're seated). However, the front rotor of the avid BB5s (road) i just bought can only be fit on the left fork if I am to follow the installation instructions to the letter - ie rotation must follow the arrow, and the writing must be facing outward. Can I use this rotor on the right hand side? That is, keep the rotation correct, but have the writing facing inwards? Are both sides the an avid rotor the same? I assume its the direction of rotation that is the important bit, and not the surface. Thanks, PB


Rotors are identical on both sides but are marked to ensure correct rotation as they aren't bi-directional. Few hubs and forks allow for a right hand mounted disc so rotors are only marked for left hand set up. The water and mud shedding capabilities drives the design and direction they should turn.

The earlier Roadrat RB2 was designed for a right hand mounted disc brake (outwards facing on front fork) to negate pressures put on the wheel when braking. The wheel was simply reversed in the drop out. The new RB3 fork has a left hand mounted disc brake but uses a 9mm thru-axle design which integrates with current 9mm QR hubs. Lawyer lugs achieve the same thing.

  • According to their specifications and this pic of a roadrat from cotic's flickr, there are right-side mounted discs on some roadrats. – freiheit May 11 '14 at 23:05
  • Thanks, that's what I wanted to hear. The mount is definitely on the right - I did think I was going mad for a minute. Opposite to your pick, front-right, rear-left, which surprised me. Its a 2009 model so perhaps before road discs were standardised as mtbs. Cheers! – user2175481 May 11 '14 at 23:10
  • Missed that!! I'll update and only leave the answer to the actual question! – DWGKNZ May 12 '14 at 1:07
  • Does it really matter for road use if its primarily for water and mud shedding ability which determines the rotation? – Batman May 12 '14 at 2:37

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