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rockshox 426 dual air u-turn

gbrnolegbrnole Posts: 395
edited May 2008 in MTB workshop & tech
how do you tell when your forks need a service?

I've had these pikes about a year and ride frequently but just lately I don't seem to be as satisfied with their performance. I am quite experienced with forks and have owned a number of fox, rockshox forks but just seem to have an issue dialling these pikes in as i want them to feel.

Problem I have is that I set up both air chambers to be equal then adjust to get the right feel, I want them a bit plusher so I add more neg air but then the travel gets sucked down and I'm not getting full 140mm. If I add more pos air they're too stiff?? I really want a more progressive feel to them, ie. Soft travel at the start of stroke to absorb small bumps and then firming up as the travel increases for the bigger stuff, at the moment if I set the travel to be soft enough for small bumps I bottom out on the big stuff. At present I've got them quite stiff, if I add more neg air I lose travel if I lessen the pos air I lose travel and sags too much or they're too soft.

In all my adjustments I've noticed oil coming from the air valves on changing the air pressure and wondering if the oil could be depleted causing bad performance.

I've debated getting some rs lyrics or fox 36's, anyone know the feel of these forks
Ibis Mojo SL-r

Posts

  • newbiketimenewbiketime Posts: 86
    I guess you have had a good play with the setting. On many of the newer forks the pedal platform cam make the damping feel relatively died on small bumps. Its worth a methodical fiddle forking though each adjustment and noting exactly how they impact the fork before doing anything radical. You may wish to try running slightly less air pressure and a marginally increased sag. This will make the forks naturally more compliant. I would have both air chambers relatively equal in pressure. Virtually every fork now has got rid of the duel chamber in favour of just a self levelling setup now as it was a bit of a pointless thing to have. If you have done that and there still feeling a bit down I would be tempted to service them if there getting on a bit. When the oil starts to get low in them they start to become much less progressive. If you want to have them more progressive you can always slightly over fill the oil. I would recommend by no more than a cc or two (5 is a absolute maximum). Also a nice lubrication of the fork always make it feel more supple again. Though if there well used and starting to get play I would send them off for new bushes.
  • dave_hilldave_hill Posts: 3,877
    First up, are they 426s or 454s? The 426 isn't U-turn, the 454 is
    alex.hulme wrote:
    how do you tell when your forks need a service?

    At risk of sounding obvious, there's a service schedule in the manual. Follow that.
    Problem I have is that I set up both air chambers to be equal then adjust to get the right feel, I want them a bit plusher so I add more neg air but then the travel gets sucked down and I'm not getting full 140mm. If I add more pos air they're too stiff??

    That's how dual air works! The negative chamber pulls the fork down into it's stroke, so if you've got your sag set correctly you're never going to get the full 140mm travel
    I really want a more progressive feel to them, ie. Soft travel at the start of stroke to absorb small bumps and then firming up as the travel increases for the bigger stuff, at the moment if I set the travel to be soft enough for small bumps I bottom out on the big stuff. At present I've got them quite stiff, if I add more neg air I lose travel if I lessen the pos air I lose travel and sags too much or they're too soft.

    Use your air chambers to set the sag and sensitivity, then forget it. Use your compression damping adjuster and floodgate to fine-tune how the forks react.

    Just to give you an idea, I weigh 13,5 stone and I've got 150lbs positive, 160lbs negative and about 2,5 turns of positive floodgate. I then use the compression adjuster to regulate how the forks react - locked out for climbing, wide open for mad descending. In the 18 months I've had them I've never bottomed them out once.
    In all my adjustments I've noticed oil coming from the air valves on changing the air pressure and wondering if the oil could be depleted causing bad performance.

    Yep, they all do it! It tells you this in the owners manual and that it is perfectly normal. That's why you need to follow the service schedule as detailed (it's only lubricating oil, it's nothing to do with the damping circuit).
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  • gbrnolegbrnole Posts: 395
    Thanks for the replies/advice...
    First up, are they 426s or 454s? The 426 isn't U-turn, the 454 is

    Yes sorry, they're the 454's
    Just to give you an idea, I weigh 13,5 stone and I've got 150lbs positive, 160lbs negative and about 2,5 turns of positive floodgate. I then use the compression adjuster to regulate how the forks react - locked out for climbing, wide open for mad descending. In the 18 months I've had them I've never bottomed them out once.

    I weigh the same so ill give those settings a go and see how i get on

    Thanks
    Ibis Mojo SL-r
  • dave_hilldave_hill Posts: 3,877
    Sorry, forgot to say make all your adjustment with the forks fully extended to 140mm.
    Give a home to a retired Greyhound. Tia Greyhound Rescue
    Help for Heroes
    JayPic
  • gbrnolegbrnole Posts: 395
    Ok - now whats with the 'internal floodgate' as described in the user guide?
    the rebound adjuster on the bottom right fork leg can be used to adjust internal Floodgate models.
    Gently pull downward on the rebound adjuster for removal. Remove the gold ‘Gate’ dust cap and insert the
    2.5mm hex end of the rebound adjuster into the Floodgate. Don’t forget to re-install the adjuster after use!
    Ibis Mojo SL-r
  • dave_hilldave_hill Posts: 3,877
    Well if you read the relevant section, it explains that the 454 has an external floodgate adjust...
    Give a home to a retired Greyhound. Tia Greyhound Rescue
    Help for Heroes
    JayPic
  • supersonicsupersonic Posts: 82,708 Lives Here
    When the fork is locked out, the floodgate sets the force required for the lock to blow off.

    Try setting the fork up from scratch - let all the air out of the negative chamber, then the positive chamber. Refill the positive, but add 5psi ecxra to the negative. Make sure the compression damper is set to minimum.

    Now ride and see how it feels!
  • gbrnolegbrnole Posts: 395
    Yeh i have the fork set up a lot better now.
    Well if you read the relevant section, it explains that the 454 has an external floodgate adjust...

    Yes and it also says that
    the rebound adjuster on the bottom right fork leg can be used to adjust internal Floodgate models..... Remove the gold ‘Gate’ dust cap and insert the
    2.5mm hex end of the rebound adjuster into the Floodgate.
    and refers to this internal floodgate - from that im assuming that the 454 has an internal floodgate also or am i missing something?
    Ibis Mojo SL-r
  • alex.hulme wrote:
    Yeh i have the fork set up a lot better now.
    Well if you read the relevant section, it explains that the 454 has an external floodgate adjust...

    Yes and it also says that
    the rebound adjuster on the bottom right fork leg can be used to adjust internal Floodgate models..... Remove the gold ‘Gate’ dust cap and insert the
    2.5mm hex end of the rebound adjuster into the Floodgate.
    and refers to this internal floodgate - from that im assuming that the 454 has an internal floodgate also or am i missing something?

    Manuals will quite often have generic sections that aren't relavant to specific models in the range hence it says 'can be used to adjust internal floodgate models'. Since yours has an external floogate, that section can be disregarded.
  • gbrnolegbrnole Posts: 395
    ok nice, I've got them feeling a lot better now. I just drained all air and started from scratch. Thanks for all the help, understand them a lot better now
    Ibis Mojo SL-r
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