disc rotor size

struck
struck Posts: 320
edited February 2009 in MTB workshop & tech
hi,

my old M4 rear disc rotor was 180mm and new Tech M4 rotor size is 183mm. it looks huge on my 24" wheels, is it too big?

Hope Tech M4 183mm on rear 24" MTX rim, 24/7 hub
http://www.pinkbike.com/photo/894550/

Comments

  • nicklouse
    nicklouse Posts: 50,675
    ? what are you asking? the discs are the same (in all reality).
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • struck
    struck Posts: 320
    sorry, a bit vague.

    basically im asking if a rotor can be too big for a wheel? :? would a powerful brake and big rotor be too much for a small wheel?? ...
    http://www.pinkbike.com/photo/894550/
  • mcbazza
    mcbazza Posts: 251
    too big/much - depends on what you are doing with the bike, that you expect performance out of the brakes.

    Since you run a smaller wheel (than us 26-ers) you are effectively getting more leverage than if the same brake/rotor were on a 26in wheel.

    So, if you aren't riding it XC/DH, and are perhaps just riding it locally and/or DJ'ing then you could say that it has more stopping ability than is required.
    Stumpy, Rockhopper (stolen!) & custom SX Trail II - that should do it!
  • struck
    struck Posts: 320
    thanks. i ride everything DH/street/trials all on one bike. its amazing.

    hardtails all the way
    http://www.pinkbike.com/photo/894550/
  • mcbazza
    mcbazza Posts: 251
    Well, then the answer is simple:-

    Do your brakes stop you in time?
    Do you suffer from fade?
    Do you run the risk of having something hit the disc due to poor clearance between obstacle and rotor?
    Are you a weight weenie?

    If you answer 'yes' to...
    1st one - your brakes are fine.
    2nd one - your brakes are too small (or you drag them!).
    The 3rd/4th - your brakes are too large.
    If it's a mixture of answers, then it's your call.

    if you really want the same/similar stopping power, but with smaller discs. Then this is possible. But, you'd have to look at changing your levers/calipers/pads/rotors (some/all of these).

    In summary - you're fine!
    Stumpy, Rockhopper (stolen!) & custom SX Trail II - that should do it!
  • struck
    struck Posts: 320
    cheers, thats good to know. for some reason i thought you could damage a wheel by putting a monster brake on it...maybe on bigger machines..

    might buy smaller rotor just for extra clearance, it currently looks almost the same size as the wheel! a bit silly.

    Hope Tech M4, i assume for 160mm rotor all i need is the 160mm adaptor
    http://www.pinkbike.com/photo/894550/
  • mcbazza
    mcbazza Posts: 251
    struck wrote:
    cheers, thats good to know. for some reason i thought you could damage a wheel by putting a monster brake on it...maybe on bigger machines..
    Ah. The bigger stress is placed upon the forx/frame. Of course, you should check that both are rated to rotors of that size.
    Stumpy, Rockhopper (stolen!) & custom SX Trail II - that should do it!

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