Wierd (?) noise from rear shock- Mtbr.com
Results 1 to 8 of 8
  1. #1
    mtbr member
    Reputation: TordFuglstad's Avatar
    Join Date
    Apr 2015
    Posts
    29

    Wierd (?) noise from rear shock

    So I'm quite new to this rear shock game, been riding bike parks with a hardtail for a few years now. Recently I decided my legs are getting to old, and acquired this setup second hand.

    The shock is a rockshox Monarch R (not exactly top of the line, to say it that way)

    Anyways, my question is this: Is the sound the shock is making in the video a normal sound? All the air is let out.

    https://youtu.be/3pZrklfH7fE

    Thanks for any help!
    A rolling photographer - TFPhoto.no

  2. #2
    Super Moderator SuperModerator
    Reputation: driver bob's Avatar
    Join Date
    Oct 2005
    Posts
    3,917
    It's hard to say from the video but it sounds like it's cavitating:

    https://www.youtube.com/watch?v=YNVofqBrFXY

    Does the noise stop when the shock is at the correct pressure for your body weight.

  3. #3
    mtbr member
    Reputation: TordFuglstad's Avatar
    Join Date
    Apr 2015
    Posts
    29
    Quote Originally Posted by driver bob View Post
    It's hard to say from the video but it sounds like it's cavitating:

    https://www.youtube.com/watch?v=YNVofqBrFXY

    Does the noise stop when the shock is at the correct pressure for your body weight.
    To be honest I just picked it out of the shed to start building the "new" bike. I can't check now if it's still there after it's set to the right pressure. Sadly.

    But is this a common sound for a shock without air that's getting compressed? If its a cavitation, does it need a full service?

  4. #4
    Super Moderator SuperModerator
    Reputation: driver bob's Avatar
    Join Date
    Oct 2005
    Posts
    3,917
    If it's still making that noise when it's set up properly then it'll most likely need a service.

    If the noise isn't there when it's set up properly then it's good to go IMO.

  5. #5
    mtbr member
    Reputation:
    Join Date
    Dec 2015
    Posts
    490
    two possibilities:
    - some lubricating oil in air spring which creates such a sound when air goes thru the dimple and equalise
    - aerated damping system
    To be sure. Unthread aircan and then check for sounds.

  6. #6
    mtbr member
    Reputation: Lone Rager's Avatar
    Join Date
    Dec 2013
    Posts
    7,187
    Quote Originally Posted by driver bob View Post
    It's hard to say from the video but it sounds like it's cavitating...
    Almost certainly not. It's aerating, air mixing with the oil. Cavitation is when the local dynamic pressure in a fluid goes below the vapor pressure of the fluid causing it to turn to gas. Suppressing it is the reason shocks have high IFP pressure.

    Cavitation: https://www.britannica.com/science/cavitation
    Do the math.

  7. #7
    Super Moderator SuperModerator
    Reputation: driver bob's Avatar
    Join Date
    Oct 2005
    Posts
    3,917
    Quote Originally Posted by Lone Rager View Post
    Almost certainly not. It's aerating, air mixing with the oil. Cavitation is when the local dynamic pressure in a fluid goes below the vapor pressure of the fluid causing it to turn to gas. Suppressing it is the reason shocks have high IFP pressure.

    Cavitation: https://www.britannica.com/science/cavitation
    What he said. My mistake.

  8. #8
    mtbr member
    Reputation: the_joe's Avatar
    Join Date
    Feb 2017
    Posts
    1,256
    Being a used shock, it needs a full damper service regardless of what sound it makes. Thats a pretty good quality shock. But it commonly lets air mix with the damping fluid (aeration) which requires full service to fix.
    My name is George. Iím unemployed and I live with my parents.
    2017 BMC Speedfox 25-622 ISO
    2017 Salsa Timberjack 40-584 ISO

Similar Threads

  1. Help with Monarch wierd noise fix?
    By Gilgo in forum Shocks and Suspension
    Replies: 8
    Last Post: 01-27-2018, 07:42 AM
  2. Noise, noise, noise!!!
    By Loos in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 7
    Last Post: 09-03-2008, 01:59 PM
  3. Wierd Shock Noise
    By benlineberry in forum Titus
    Replies: 12
    Last Post: 04-27-2008, 07:09 AM
  4. Wierd Clicking Noise????
    By ironbike1 in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 4
    Last Post: 07-17-2006, 02:01 PM
  5. Wierd noise around crankset
    By WeylessXPRider in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 1
    Last Post: 06-24-2004, 01:02 PM

Members who have read this thread: 40

Posting Permissions

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

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2019 VerticalScope Inc. All rights reserved.