RS Silver TK, Juddering under braking

matt@theforce
matt@theforce Posts: 647
edited January 2012 in MTB workshop & tech
Whilst out with SWMBO on her horse I noticed that when using the front brake the fork vibrates back and forth. I havent noticed it before on this bike.

The fork is currently fitted to a Marin Rocky Ridge (designed for a 140mm fork) with brand new Cane Creek S3 headset. There is no movement in the headset.

The fork didn't judder when fitted to my Kona but that was designed for a 100mm fork. I'm using the same brakes/wheels/rotors/pads etc.

In my mind it could be caused by the fork being too short therefore not sittting at the correct angle? What are your thoughts?

Thanks
Matthew

Comments

  • Chunkers1980
    Chunkers1980 Posts: 8,035
    You've got about 2 degrees less head angle, so the fork will be more virtical. might be causing the problem.
  • 386ka
    386ka Posts: 479
    Check for play in the fork bushings. Also, the slacker HA will in theory put bigger stress on the fork while braking.
    A much loved, Giant Trance X3 2010
  • The Rookie
    The Rookie Posts: 27,812
    386ka wrote:
    Check for play in the fork bushings. Also, the slacker HA will in theory put bigger stress on the fork while braking.
    In theory yes, in practice irrelevant - especially if he has juddering even on moderate braking!

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Chunkers1980
    Chunkers1980 Posts: 8,035
    He doesn't have a slacker head angle.
  • matt@theforce
    matt@theforce Posts: 647
    Everything feels nice and tight, I think the fork has only done about 300-400miles and most of that is road/light trail use.

    In terms of braking strength, the judder is most noticable around 4mph going downhill holding my speed steady (rear brake also in use)
  • vmgscot
    vmgscot Posts: 120
    Might be worth checking brake alignment... my Revs were shuddering recently and everything seemed fin but was due to disc not centred quite right between pistons. Just a thought
    vmgscot
  • 386ka
    386ka Posts: 479
    vmgscot wrote:
    Might be worth checking brake alignment... my Revs were shuddering recently and everything seemed fin but was due to disc not centred quite right between pistons. Just a thought
    This is true too, Avid rotors can create pulsing, and juddering if the caliper is not aligned properly.
    A much loved, Giant Trance X3 2010
  • matt@theforce
    matt@theforce Posts: 647
    I shall re-align my caliper on Tuesday when I finish my next batch to shifts and get out and try it out.

    PS.. I'm running M535's (Shimano Deore) brakes
  • matt@theforce
    matt@theforce Posts: 647
    I've been full of cold all week so only managed a 2mile route to see if re-aligning the caliper worked.

    So far so good :D , now looking forward to my next shift rotation off to get out riding again 8)

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