Forum home Mountain biking forum MTB workshop & tech

Shiimano post mount adaptors

SwitchbladeSwitchblade Posts: 23
edited November 2012 in MTB workshop & tech
Hi there,

This may come across as a silly question but here goes.

I want to fit a bigger rotor to the rear of my bike, the frame is post mount as is the caliper. Shimano have post - post mount adaptors BUT they seem to be listed for front usage, is this more a typo and can say a 180 or 203mm post - post Shimano adaptor be used on the rear????

Thanks in advance.

Dave.

Posts

  • nicklousenicklouse Posts: 50,675 Lives Here
    for the rear use the same measurements as for a post to post front unless you have alternative mounts on the frame.

    what frame?
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • It's a 2012 GT Avalanche 1.0 frame so i assumed the post mount on the rear is the same as on forks.

    Dave.
  • cooldadcooldad Posts: 32,599
    As a matter of interest, why do you want a bigger one on the back.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Well the rear 160mm needs replacing, it's a little buckled and i've noticed it's scored and i already have some new discs knocking around, one 180mm and two 203mm so thought i use one of those..........obviously the 203mm is probably too big for the rear lol.

    Thought i could go 203mm front, 180mm rear????

    I also have a couple of perfectly good condition Hayes 160mm rotors.

    For general XC would it be best to stick to 160mm F & R ????? would going to a bigger front and rear set up only be useful for an aggressive rider or DH riding or would i get better modulation, last thing i'd want is to suddenly make the brakes become more grabby and lock up all over the place due to being overkill.

    Thanks for any advice, new to all this.

    Dave.
  • Xc 180f 160r
  • cooldadcooldad Posts: 32,599
    They would be more grabby - you would get less modulation. If you actually need more braking power, then maybe 180mm on the front, I wouldn't go larger than that on a short travel XC bike.
    The rear does very little braking, and the harder you brake, the less it does as all weight is transferred to the front. Chances are it will just lock up. Even DH types manage happily with 160, or even 140 on the rear.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The RookieThe Rookie Posts: 27,802
    For XC 160/160 or even 160/140 will be fine, bigger disc - more weight.

    What brakes?
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • sigorman85sigorman85 Posts: 2,536
    I have 203 on the front and 180 on rear it works fine for me
    When i die I just hope the wife doesn't sell my stuff for what I told her I paid for it other wise someone will be getting a mega deal!!!


    De rosa superking 888 di2
  • cooldadcooldad Posts: 32,599
    sigorman85 wrote:
    I have 203 on the front and 180 on rear it works fine for me
    Right, that's good enough for me - off shopping for monster rotors.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
Sign In or Register to comment.