Rear derailleur clutch?

ben@31
ben@31 Posts: 2,327
edited March 2015 in MTB beginners
Hi,

I'm new to mountain biking and have been riding mine for 2 months now quite happily. I cant think of a time when I've really noticed the chain slap and the rear derailleur does change better than my road bike's. The only time I've had a problem in the past is when the MTB's been deep in clay mud and its clogging stuff up (which is avoidable).

When I was cleaning my not so muddy MTB today and getting up close and personal, I noticed a on / off switch on the rear derailleur. Having a play around I found out that the switch was set to off.

The rear is a Shimano Deore XT Rear Derailleur RD-M786 and I've read in the marketing stuff that it has a shadow clutch. I've no idea what that does? But a quick look on Google said something about tension and chain slap?

I thought the clutch was on full time. But as it has actually always been off and I've never noticed, I'm wondering what difference does the clutch actually make? Is it worth switching it on ?
"The Prince of Wales is now the King of France" - Calton Kirby

Comments

  • cooldad
    cooldad Posts: 32,599
    Presumably not.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The Rookie
    The Rookie Posts: 27,812
    The clutch prevents the weight of the chain pulling it out of line (vertically) when the bike is going over rough ground, it may be a clutch but in fact acts like a damper to the mechs tensioning spring.

    With the clutch on it is less prone to chain slap (where the weight of the chain takes it far enough to 'slap' the chainstay), also it will help to keep the chain on a single front chainring setup.

    The clutch has an off switch as removing the rear wheel with the clutch on is a PITA.

    Shifting is slightly better with the clutch off from most people reports.

    If you have no downside of leaving it off, leave it off!
    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.
  • lostboysaint
    lostboysaint Posts: 4,250
    Yes it is, otherwise it wouldn't be there. ;)

    Much more noticeable on 1x set ups where there's no chain retention on the front ring.
    Trail fun - Transition Bandit
    Road - Wilier Izoard Centaur/Cube Agree C62 Disc
    Allround - Cotic Solaris
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    I use mine a lot. It stops the chain slapping around over rough ground at speed and helps stop it dropping off the chain ring.
    Transition Patrol - viewtopic.php?f=10017&t=13070235
  • paul.skibum
    paul.skibum Posts: 4,068
    I dont use mine much as I find it makes the gear changes less crisp and has little benefit when riding.
    Closet jockey wheel pimp whore.
  • divingmoose
    divingmoose Posts: 540
    On the x01it says it has a roller ball clutch how does this work is it on all the time as I know with the xt you can move it on and off
  • The Rookie
    The Rookie Posts: 27,812
    It still acts like a damper, yes it is on all the time, it is a better damper as the roller ball is more speed sensitive (speed of movement of the mech that is) than a clutch type friction damper but the clutch type has the benefit of having more stiction which for a rear mech is a good thing for when running in a single gear.
    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.
  • divingmoose
    divingmoose Posts: 540
    Thanks mate

Categories