Results 1 to 10 of 10
  1. #1
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    75

    What rotor size do I need?

    I'm working on a build. I have purchased some new Avid X0 brakes but they don't come with rotors.
    Can I use any size rotor I want with these brakes by placing shims under the caliper mounting brackets, or do I need different mounting brackets for different rotor sizes?
    If I wait until the brakes arrive, is there any way to tell what size rotor I can use with the brackets that come with them?
    I would love to buy rotors now but I wonder if I have to wait until the brakes arrive to size up the situation.

    Thanks for the help

  2. #2
    rebmem rbtm
    Reputation:
    Join Date
    Apr 2007
    Posts
    2,661
    Click on the photos I posted in this thread, they'll give you some info on mounting adapters.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    75
    Thanks for the pics. The brakes I purchased come with post mounts included (from what I can tell in the pics). It looks like I just have to play with the washers and spacers to get the pads to contact the rotor on the outer friction surface evenly.
    Is this a correct interpretation?

  4. #4
    mtbr member
    Reputation: Saul Lumikko's Avatar
    Join Date
    Oct 2012
    Posts
    1,017
    To match the caliper and rotor size, you need the correct adapter.

    The concave and convex washers are only installed one way and their purpose is to allow another axis of adjustment for the caliper. They are not swapped around.

  5. #5
    mtbr member
    Reputation: nvphatty's Avatar
    Join Date
    Mar 2012
    Posts
    4,365
    Quote Originally Posted by Saul Lumikko View Post
    To match the caliper and rotor size, you need the correct adapter.

    The concave and convex washers are only installed one way and their purpose is to allow another axis of adjustment for the caliper. They are not swapped around.
    this!! along with specific front & rear adaptors.

  6. #6
    mtbr member
    Reputation: lew242's Avatar
    Join Date
    Aug 2008
    Posts
    491
    Choose your rotor size carefully, my rule of thumb is if the terrain is over 200 meters vertical drop 180mm rotors and over 500 meters 200mm if you can afford the weight penalty. I also much prefer the bite with a 180mm rotor over a 160mm.

  7. #7
    On your left.
    Reputation:
    Join Date
    Jan 2004
    Posts
    1,166

    What rotor size do I need?

    Unless weight is a primary concern, I suggest 180mm front and rear. On the trail, I've always found situations that expose the limits of smaller rotors and a larger front rotor while OK is more sensitive to alignment. I also prefer non-lightweighted rotors because they seem smoother, quieter, more fade resistant and more powerful than heavily vented ones.
    M

  8. #8
    mtbr member
    Reputation: borabora's Avatar
    Join Date
    Feb 2011
    Posts
    339
    If you weigh less than ~190 lbs then 180 front and 160 rear should be fine for most scenarios. Since you are doing your own build and using high-end brakes I assume that you aren't a beginner. If you are a beginner then you are likely to use you brakes much more and bigger rotors might be better. If you plan on racing then maybe 160/160.

    In then end, you can always change the rotor size if you feel like you want larger or smaller. Keep in mind that frames and forks are usually spec'ed to a max rotor size.

  9. #9
    mtbr member
    Reputation:
    Join Date
    Apr 2013
    Posts
    75
    Quote Originally Posted by borabora View Post
    If you weigh less than ~190 lbs then 180 front and 160 rear should be fine for most scenarios. Since you are doing your own build and using high-end brakes I assume that you aren't a beginner. If you are a beginner then you are likely to use you brakes much more and bigger rotors might be better. If you plan on racing then maybe 160/160.

    In then end, you can always change the rotor size if you feel like you want larger or smaller. Keep in mind that frames and forks are usually spec'ed to a max rotor size.
    Yeah, I've been riding for a few years and decided to build what I want. This will be a long travel hardtail. I have stripped and built bikes in the past and do all of my own maintenance. Since I have always purchased complete bikes, the brake mounts and rotor sizes were already matched for me. Thanks to this thread, I now know that I can buy whatever rotor size I want and buy the corresponding caliper mounting brackets to match (within the limits of my frame and fork).
    Yes, I have decided to go with 180/160 and ordered them yesterday. I weigh 160 pounds and I think that will be enough for XC and light all mountain duty. My enduro bike has 180/180 and it feels like plenty of braking power on long descents.
    Last edited by dboneslick; 05-12-2013 at 04:13 AM.

  10. #10
    Happy Trails
    Reputation: Scott In MD's Avatar
    Join Date
    Sep 2008
    Posts
    914

    What rotor size do I need?

    Good decision.

Similar Threads

  1. What is the best size rotor for me?
    By Coondog#77 in forum Brake Time
    Replies: 4
    Last Post: 08-14-2012, 08:38 PM
  2. Rotor Size????
    By bowler1 in forum Brake Time
    Replies: 7
    Last Post: 05-09-2012, 12:01 PM
  3. rotor size?!??
    By -eddie. in forum Brake Time
    Replies: 9
    Last Post: 11-01-2011, 05:59 AM
  4. rotor size ?
    By Wayne Meuir in forum Brake Time
    Replies: 4
    Last Post: 05-12-2011, 06:12 AM
  5. Rotor Size
    By adkbiker1 in forum Cannondale
    Replies: 3
    Last Post: 04-12-2011, 02:23 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •