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Rocky mountain ,Fusion 27.5

Discussion in 'General Discussion' started by Dale shepherd, Oct 21, 2015.

  1. Dale shepherd

    Dale shepherd New Member

    Hi ive recently taken up mountain biking after riding a bmx for the last 15 years . I've brought myself a rocky mountain fusion 27.5 hardtail. and ive noticed that when im travelling downhill fast or going off drop-offs my rear derailleur hits the chainstay really hard making a horrible noise . Is there anything that can cure this or any upgrade i can buy to solve the problem

    WP_20151008_20_43_10_Pro.jpg
     
  2. Greg

    Greg MTB Rider Staff Member

    Hi Dale, sounds like it's your chain slapping on the chain stay rather than the derailleur, pretty common thing. First thing is to make sure you have a chain stay protector, you can either buy one or wrap an old inner tube around the chain stay and cable tie each end in place.
    To stop the chain slap you need a rear derailleur with a clutch (called Shadow + or Plus), I had a quick search online and your Rocky Mountain looks like it has a 9 speed drive train, if that's correct then Shimano don't make a Shadow + derailleur that I'm aware of - only for 10 Speed.
     
  3. Dale shepherd

    Dale shepherd New Member

    Yeah it is a 9 speed drive train. ive just purchased a chain stay protecter to try out but ive just bounced the bike up and down and its definately the derailleur heres a few pictures if you want to take a look

    WP_20151021_21_35_27_Pro.jpg

    WP_20151021_21_35_34_Pro.jpg
     
  4. Greg

    Greg MTB Rider Staff Member

    Ok I see now, has it always done this, or is it something that started to happen?
     
  5. Greg

    Greg MTB Rider Staff Member

    Also does it happen in all gears?
     
  6. Dale shepherd

    Dale shepherd New Member

    Ive only had the bike 2 months. yes in all gears
     
  7. Dale shepherd

    Dale shepherd New Member

    sorry yes it has always done it .
     
  8. Greg

    Greg MTB Rider Staff Member

    This appears to be a common issue with the Deore M591 (non-shadow) derailleurs. The Deore M592 Shadow derailleurs are designed to tuck in closer to the cassette and have a stronger spring which stops it swinging forwards so easily.

    Getting a Shadow derailleur might be the only way to stop the problem you're having completely... However two things to check before spending out on new parts, which might reduce the issue, would be the chain length and then adjusting the B-Tension screw. You'll then probably need to re-index the gears too.
    Best to do this kind of work on a bike stand so you can freely pedal the bike whilst fine tuning things, you'll also need a few tools: Chain Link tool, screw drivers and an allen key if the cable position needs adjusting. If you're not confident with tweaking the derailleur then pop in to your local bike shop (NOT Halfords) and they should be able to get the whole process done in 15 or 20mins tops.
     

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