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Help a light rider with his first air forks.

PlyphonPlyphon Posts: 433
edited December 2012 in MTB workshop & tech
Hiya,

So i'm not the heaviest of guys - 9 stone 8 on a good day.

Forks are RS Revelation RLT, 140mm

To get anywhere near 20% sag (which is 28mm) I have positive chamber at 55psi and negative at 40psi. And ever then I'm probably not hitting that 20% but I haven't tried with gear on yet so it's probably in the ballpark.

Does this seem a bit low to anyone? I know the printed RS figures are way out but this seems a bit extreme.

The initial stroke of the forks seems very hard compared to my previous Recon Silver (coil) forks - is this normal?

Cheers.

edit: btw I am setting the sag via the bike radar approved way of standing in the attack position and measuring how far the o ring moves.

Posts

  • Greer_Greer_ Posts: 1,716
    Which chamber did you fill first? Positive? It does seem quite low ....
  • PlyphonPlyphon Posts: 433
    Yea emptied both then Positive to negative, however when adjusting I'd normally do the neg first letting out 5psi at a time.
  • Greer_Greer_ Posts: 1,716
    Are they new or second hand?
  • bartimaeusbartimaeus Posts: 1,812
    And are you in 'the attack position'? If you are just sitting back on the saddle your weight will be over the back wheel, not the front.
    Vitus Sentier VR+ (2018) GT Grade AL 105 (2016)
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  • PlyphonPlyphon Posts: 433
    Greer_ wrote:
    Are they new or second hand?


    They are 2nd hand indeed. Could it be service time?


    And yup, "attack position" is affirmative.
  • The RookieThe Rookie Posts: 27,802
    Worth a service just to be sure. RS are very easy to service.

    What is the positive pressure from the RS chart for your weight?
    Current steed - Whyte T129, 2013 frame, mongrel Revelations, Giant dropper, Stans S1 wheelset. 12, Magura Trail Sport brakes, 1x11. 12.8Kg
  • cameraukcamerauk Posts: 1,000
    If you put more air in the negative side than the positive side it should make the beginning of the stroke softer
    so try 55 psi in positive and 65 in negative and see how that goes
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  • PlyphonPlyphon Posts: 433
    camerauk wrote:
    If you put more air in the negative side than the positive side it should make the beginning of the stroke softer
    so try 55 psi in positive and 65 in negative and see how that goes


    are you sure? the RS manual says for a firmer "XC orientated" feel then you up the pressure in the neg, and for a better small bump compliance you do the opposite.... I mean - doesn't hurt to try so I'll give it a shot tomorrow :)
  • Greer_Greer_ Posts: 1,716
    For more small bump compliance you put more in the negative side.
  • supersonicsupersonic Posts: 82,708 Lives Here
    Plyphon wrote:
    camerauk wrote:
    If you put more air in the negative side than the positive side it should make the beginning of the stroke softer
    so try 55 psi in positive and 65 in negative and see how that goes


    are you sure? the RS manual says for a firmer "XC orientated" feel then you up the pressure in the neg, and for a better small bump compliance you do the opposite.... I mean - doesn't hurt to try so I'll give it a shot tomorrow :)

    More negative air pressure than the positive for a softer feel at the start of the stroke.
  • PlyphonPlyphon Posts: 433
    Yeah seems I've really outdone myself this time - checked the manual I read it (or remembered it) the wrong way round - cheers guys! Will try adding more negative tomorrow and see if I can't achieve proper sag with a nice feel and not bottomig out dropping off curbs :)
  • Start at something like 5 or 10% more in the negative, so about 60psi.

    BTW dual air revs are lovely when set up right.
  • miss notaxmiss notax Posts: 2,572
    Obviously not the case here (hope you get them sorted :D ) but in my limited experience some forks simply are not set-up for lighter riders.... I had some Marzocchi Bombers on the Kona which I could not get any movement out of. Took practically all the air out of them etc but I really struggled with them - my weight was off the bottom of the weight 'chart'. In the end I got so fed up I sold them and got some nice plush Fox 36's - lovely :D

    Bit peed off with Kona though, it was a ladies specific freeride bike and they put forks on that were not suited to lighter riders. Or are all ladies that want a freeride bike meant to be more 'well built' types?!!! IDIOTS :twisted:

    And breathe.....
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  • supersonicsupersonic Posts: 82,708 Lives Here
    The charts are just guides - if a full air fork, use whatever pressure is necessary to give you the sag is want.
  • PlyphonPlyphon Posts: 433
    so,

    50 positive, 60 negative seems to give me the rough 20% sag i'm after with a plush feel, I reduced the rebound so it doesn't feel like its packing down.

    I'll measure again with my kit on before this weekends ride but I think we're sorted!

    Cheers all, now to learn how the compression control thingie works....
  • Greer_Greer_ Posts: 1,716
    Rebound affects how quickly the fork extends to stop it feeling like a pogo stick, compression damping affects the downstroke.
  • PlyphonPlyphon Posts: 433
    yeah I like my rebound to be quite quick, thats sorted. never had a fork with compression tho but i'll start with no dampening and if i feel like I falling through the floor every bump i'll start to ramp it up
  • PlyphonPlyphon Posts: 433
    can someone clarify - the motion control compression damper adjustment only effects the fork when locked out? it has no bearing on how the fork acts when not-locked?
  • Greer_Greer_ Posts: 1,716
    Yep, MoCo allows a few cms of travel to try and help the front wheel maintain grip when locked out. It has no effect when it isn't. The TK damper allows no movement at all when locked out. (except blowoff)
  • PlyphonPlyphon Posts: 433
    And finally the final pieces of the puzzle click into place - thanks Greer_!
  • supersonicsupersonic Posts: 82,708 Lives Here
    Sorry, but that is wrong.

    Motion Control on this fork is an adjustable compression damper. At one end it is fully open, at the other fully closed, which locks the fork out. You can set it anywhere in the middle, to progressively add damping.. This can prevent fork dive and bob. When locked out, the fork retains about 20mm of travel to aid traction. Note that some Poplocs do not allow you to make this adjustment.

    But you also have Floodgate adjust. This is a blow off valve - you can set it so when the fork is locked it only moves on bigger hits. Too little though and the fork may not lock at all. it also has some effect when the MoCo adjuster is about 3/4 shut too.

    Turnkey is an on/off lockout with no adjustment inbetween. The blowoff valve is fixed, but the fork is still designed to move slightly for traction.
  • supersonic wrote:
    But you also have Floodgate adjust. This is a blow off valve - you can set it so when the fork is locked it only moves on bigger hits.

    I always thought this worked in exactly the same way to ProPedal or SPV - is that right?
  • supersonicsupersonic Posts: 82,708 Lives Here
    It can be adjusted to set it up the same, yes.
  • PlyphonPlyphon Posts: 433
    I see that now - I don't seem to be able to set my lockout at anywhere other than fully open or fully closed - this is with a remote - something wrong or?

    Edit: I now see "Note that some Poplocs do not allow you to make this adjustment." - myth busted!
  • supersonic wrote:
    It can be adjusted to set it up the same, yes.

    thought so - ta
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