Viewing 40 posts - 1 through 40 (of 49 total)
  • Rock Shox Revelation – can't get along with them
  • dang100
    Free Member

    Hi,

    I bought a second hand Yeti 575 with Rock Shox Revelation (U-Turn) forks in October. I’ve been fiddling with it to set it up right and I can’t seem to get the forks to feel right.

    They soak up the big bumps OK but they feel like sometimes they dive under braking and at the end of a long set of bumps. I think it’s that I can’t get enough rebound on them. I’ve got the rebound as fast as it will go and I tried letting some air out of the negative chamber to improve the rebound but that just meant they didn’t soak up the little bumps.

    At the moment I actually prefer the 100mm /€80 forks I’ve got on my 12-year old hard tail!

    Anyone got any ideas?

    Cheers,

    Dan

    Jammy111
    Free Member

    have u tried turning fiddling with the compression damping? if youve got the non-poploc version turn the blue knob on the top of the right leg about 30% of the way round to full lockout. this adds a bit of damping and should help with dive

    EDIT: Have a read of this, http://www.bikerumor.com/2010/08/20/tech-article-how-rockshox-motion-control-works/ it really helped me to figure out how to set mine up properly

    stevenmenmuir
    Free Member

    Get them serviced?

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    dang100
    Free Member

    @Jammy11 – ah that could be it actually. It’s the one thing I haven’t fiddled with much. To be honest I didn’t really understand it so I left it alone.

    @stevenmuir – an option. But it feels more like an issue of set-up than servicing.

    Thanks for the quick replies both of you.

    PeterPoddy
    Free Member

    A service will help for sure.

    But you’ve got to go back to basics to set them up too: 25-30% sag, keep the +ve and -ve pressures the same (or maybe 5-10psi higher in the -ve). Having LESS -ve pressure will make them a bit less sesitive. Rebound damping only works on the rebound (extending) stroke and is menat to stop the forks feeling harsh. If the rebound is too fast they’ll fell harsh, bouncy or skittish….

    LoCo
    Free Member

    Have a look at my setup guide and set the pos/neg pressures as detailed above.

    http://locotuning.co.uk/tech-info.html

    Rorschach
    Free Member

    Getting them Push’d helps with the compression damping thing-basically copied by Sram with Blackbox.Makes them better over the bigger stuff and a bit less divey but you do lose some car park plushness.
    Lack of speed sensitive damping makes non blackbox stuff a bit one dimesional (works in narrow speed range).
    Edit-Don’t know whether TF still deal with Push.

    glenh
    Free Member

    It’s because, unless they are black box versions (or been ‘pushed’) then they just have a crappy orifice rebound damper, so they pack down on repeated hits or when riding fast.

    beanieripper
    Free Member

    tbh I run both black box an motion control and the difference is noticable on some stuff but its a subtle improvement. moco revs are ace if set up right, as youve been told, do a lowers service and add a bit of compression damping…

    Digger90
    Free Member

    Go coil.

    bigjim
    Full Member

    Lower leg service should help, RS seem to barely put any oil in them from new. Mine had no oil in one leg and some watery emulsion in the other when I serviced them.

    duir
    Free Member

    Send them to TF Tuned and cough up. You won’t recognise them and they will become very plush, reliable and have all the issues resolved.

    LoCo
    Free Member

    *Other suspension tuners are also available* 😉

    mrh86
    Full Member

    As what bigjim said. I stripped my new revelation rlt ti forks down as soon as I got them last week to find virtually no oil in the lowers.

    TandemJeremy
    Free Member

    Given how clear and bullshine free LoCos advice is I would be inclined to trust him

    I would spend some time trying to set them up first of all I think you are a bit confused.

    Fast rebound is minimal damping but you say you want more rebound?

    Print off LoCos set up guide and spend a day doing taht. Do you have too much rebound damping on and are getting pack down> Try to avoid putting compression damping on – it just ruins the compliance. If you have the sring and rebound right then you shouldn’t need any extra compression damping

    dang100
    Free Member

    Thanks for all the advice, everyone.

    TandemJeremy – yes I´m completely confused!

    It feels like the forks are diving forward after a long series of bumps. But at the same time they´re quite hard on the smaller bumps. They handle single, big hits well.

    Anyway I had a go at starting from scratch last night and all was going well until I found the gate adjuster, which I looked up on Google and entered into a whole new world of confusion.

    This morning they are… different. I can´t really tell until I get out tomorrow.

    If nothing else, this thread´s convinced me to give them a good service.

    LoCo – if I was anywhere near you, you´d have yourself a customer but
    I´m in Spain.

    Cheers again for all the help everyone.

    scruff
    Free Member

    I put thicker oil in mine as I dont like divey forks. Slows rebound down though.

    HoratioHufnagel
    Free Member

    I’ve tried a few that had very slow rebound, even on its fastest setting. Think its a fault. have you compared them to any others?

    TandemJeremy
    Free Member

    My advice would be to ignore the gate adjuster completely – turn it right off.

    Sounds to me like you have too much rebound so it was packing down. A basic lower leg oil change will be worth doing as well.

    takisawa2
    Full Member

    My feable understandings…
    Packing down…too much rebound.
    Spiking on small bumps (but ok on big hits)…too much compression.
    If they’re packed down the spring rate will have gone up anyway…?
    The gate is for the blow-off when locked out.
    And be realistic setting your sag. Bottoming out once or twice a ride wont hurt them.
    And this cold weather will keep oil thicker longer.

    [the above could all be rubbish/heresay/waffle] 😕

    BadlyWiredDog
    Full Member

    Tandem Jeremy talks sense… [ha, sorry, I typed that then fell about laughing for around a minute].

    Seriously, just go over to the RS web site, download the service manuals, check out the walk-throughs on eBay, then change the upper and lower leg fluids for recommended weights and volumes plus the wiper seals as well.

    At least then you know you’re starting with a standard spec fork with correct weight and amount of oil in it. Then set the positive air first, followed by the negative air at around 10psi more, use something less than the RS recommended pressures, stick the rebound somewhere near the centre of adjustment and see how they feel then adjust from there.

    Right now you don’t know what grade oil is in your forks, if the lowers are adequate lubricated for smooth movement, whether you have the right quantities etc. It’s really straightforward if you have an ounce of mechanical ability and means you start with a level playing field.

    There could be loads of stuff going on. It sounds like your forks are packing down, but if the movement is sticky, then you may be running too little air pressure as well to compensate, in which case the rebound damping might be too much even on minimum setting. Or if you’re very light, you might even need a lighter – 5w – damper oil, but for all you know, the previous owner has used 10w or 15w oil or whatever.

    Honestly, basic service on these things is straightforward, even I can do it.

    retro83
    Free Member

    dang100 – Member
    It feels like the forks are diving forward after a long series of bumps. But at the same time they´re quite hard on the smaller bumps. They handle single, big hits well.

    Anyway I had a go at starting from scratch last night and all was going well until I found the gate adjuster, which I looked up on Google and entered into a whole new world of confusion.

    It’s perfectly fine to run the forks with the compression damping dials fully open and I would suggest getting the spring rate and rebound sorted first.
    To me it just sounds like the rebound needs to be faster.

    However the floodgate is pretty simple should you wish to tune the fork more.

    There are 2 routes the oil can take on a on a regular Motion Control fork during a bump.

    * Through the main port (adjusted by blue dial)
    * Through the floodgate (adjusted by gold dial)

    The blue dial allows you to change the low speed compression, e.g. to tune out brake dive, compression when you’re riding a berm, that sort of thing. Problem is that this also limits the overall speed of the fork squishing which can mean it can’t move quickly enough to absorb bumps.

    This is where the floodgate comes in.

    The floodgate allows you to choose a point where the oil is allowed to bypass the main port (blue dial setting) and flow very freely (so the fork movement is unrestricted). This is a bit like how a shimmed damper (e.g. on a Fox fork) behaves.

    For example: I like to run mine with the blue dial 75% towards being closed, with the floodgate about 6 clicks from fully open.
    This gives a firm ride which doesn’t slop about, but totally erases faster hits (rocks, roots etc).

    TandemJeremy – Member
    Try to avoid putting compression damping on – it just ruins the compliance. If you have the sring and rebound right then you shouldn’t need any extra compression damping

    Well it is personal preference to an extent, however it is impossible to make the same adjustments with just the spring and rebound damper that you can with the compression damper.
    Also as above it need not ‘ruin compliance’.

    beanieripper
    Free Member

    Just read this again…. if your rebound damping is set fast and they are still packing down it,s probably a lack of lube in the top of the left leg. If this seal is a bit dry it sticks and stops them rebounding properly, gf had some recons that did it, plus my my 2010 revs had no oil in the top of the left leg, just a blob of grease. let the air ou of them them whip off the top of the left leg (24mm socket) should be 6ml of oil in their, i bet they are dry….

    glenh
    Free Member

    Just read this again…. if your rebound damping is set fast and they are still packing down it,s probably a lack of lube in the top of the left leg

    No, it’s just the design of the rebound damper, as I said before.

    PeterPoddy
    Free Member

    Honestly, basic service on these things is straightforward, even I can do it.

    Yes, it really is. A few basic tools and some common sense sees it done. I’d say 1hr for the first time, maybe a bit more if you taske the forks off the bike. Once you’ve done it a couple of times it’s one of the easier ‘technical’ jobs on an MTB. RS forks are very, very simple inside. The first time you’ll cack yourself, but when you’re done you’ll wonder what the fuss is about 🙂

    beanieripper
    Free Member

    glenh, what b0llocks..

    glenh
    Free Member

    How so?

    beanieripper
    Free Member

    Well the guy says in his post that he prefers his 100mm /€80 forks on his 12yr old hardtail. I think if most people that bought MoCo revs had a similar experience to this with them then RS wouldnt be selling any forks and there would be alot of people posting here about how bad they are. So it seems obvious that he has some type of service/setup problem rather than poor performance due to the inherrent design of the forks. I appreciate MoCo has its limitations and BB can feel more controlled in some situations but a well setup MoCo Rev should obviously feel alot better than some old budget fork..

    glenh
    Free Member

    Fair enough, but the symptoms described are those of ‘packing down’ which is an inherent problem of the MoCo non speed sensitive orifice rebound damper. I’d be very surprised if a dry seal could produce a really significant level of high speed rebound damping (which is what the forks have too much off if they are packing down).
    Maybe he’s just more sensitive to this problem than whatever issues his cheap forks may have (especially since they probably don’t have much damping and therefore don’t pack down!).

    bigjim
    Full Member

    Maybe try this to keep it simple:

    1) Ignore floodgate completely for now, unlock the forks.

    2) Set -ve pressure to be equal to your +ve pressure to start with. My -ve chamber leaks over a few days, yours might too.

    3) Starting from no rebound, slowly adjust the rebound until it feels right over your usual bumps.

    4) Adjust the -ve pressure to suit if you feel you have too soft/hard an initial movement

    5) Then start messing around with compression damping, lockout, floodgate, etc. Personally I don’t use much compression damping, have the -ve about the same as the +ve, and a fairly fast rebound. Also I find the recommended pressures on the fork pretty high.

    Perhaps I should try to tweak them a bit more, I bought mine a couple of years ago after the gushing reviews but haven’t found them to be able to match the plushness of the fox float on the back.

    GW
    Free Member

    I’d agree with glenh. Pike/Rev rebound damping is a pretty basic/crude system that simply can’t cope.
    (not saying that’s all that’s to blame for the poor performance tho)

    retro83
    Free Member

    GW – Member

    I’d agree with glenh. Pike/Rev rebound damping is a pretty basic/crude system that simply can’t cope.
    (not saying that’s all that’s to blame for the poor performance tho)

    Agreed but on its fastest rebound setting it should be very fast indeed. Certainly not packing down.

    dang100
    Free Member

    OK – we’re getting there. Thanks to all the great advice on this thread.

    I’ve wound the compression damping off completely. The gate is about 1 turn from being completely off (4.5 turns between off and on).

    I reset the positive air pressure to get the sag right (it’s about 110psi vs the recommended 120 – 135 for my weight) and the negative air pressure around 120psi. The rebound is sort of in the middle.

    The forks feel a lot smoother and there is no more dive. They seem to be at their best once I’m going at a reasonable speed and over medium-to-big rocks / hits. They’re still not absorbing small and / or low-speed bumps.

    I’ve got two questions now:

    a) When people talk about putting the rebound damping “on” or “off”, which is which? Do I turn the nob in the direction of the tortoise or the hare? (“on” and “off” would surely be easier than tuning the forks according to Aesop’s fables)

    b) When I’ve got the pump hooked up to the negative air pressure, the pressure drops visibly in the gauge. It doesn’t happen with the +ve air so I assume it’s not a problem with the pump. Could it be that the valve is broken or loose? Is tightening or replacing it possible and / or easy?

    Thanks again for all the help.

    Dang100

    LoCo
    Free Member

    On I.E more damping is the tortoise, slower rebound means there is more rebound damping.

    The pressure drop is more when connected to the negative chamber as it is smaller than the positive, the air has to go from the valve on the fork down the hose to the gauge so increases the volume further.
    The pressure drop will be greater for a smaller air chamber.

    CaptainMainwaring
    Free Member

    They’re still not absorbing small and / or low-speed bumps.

    Before setting sag with the +ve pressure, empty the -ve chamber completely or you will get a false reading. Once sag is done, set the -ve pressure.

    I have the reboud one or two clicks on the slow side of middle – too fast and they feel like there is no small bump sensitivity. Before you fiddle with anything else try setting the -ve pressure 5-10 PSI more than the +ve – works for me

    When I’ve got the pump hooked up to the negative air pressure, the pressure drops visibly in the gauge. It doesn’t happen with the +ve air so I assume it’s not a problem with the pump

    The same thing happens when setting the +ve chamber but it’s less noticable. When you connect the pump the pressure from the fork fills the pump – more space so the pressure drops. It’s much more noticable on the -ve pressure side because it’s a very small volume, so the increase in percentage when you connect the pump is very high.

    Hopefully that makes sense

    stumpy01
    Full Member

    a) rebound damping controls how fast the fork returns from being compressed to it’s resting state.
    If you turn the dial towards the toroise you get more rebound damping – i.e. the rebound of the fork will be slower, which can lead to the fork packing down over successive large bumps if the fork doesn’t get the chance to return to it’s starting point in between hits.
    If you turn the dial towards the hare, then you get less rebound damping i.e. the rebound of the fork will be quicker, which can lead to the opposite problem of the fork feeling uncontrolled or ‘bouncy’. To me it feels like the fork is springing back into your hands.

    When I set mine up, I find out how many turns it is from one extreme to the other. I then set the dial in the middle and ride. If the fork feels like it’s uncontrolled over bumps & pushing back into your hands, then increase the rebound by turning the dial towards the tortoise a little, making the fork ‘slower’ and try again.
    If it feels sluggish and like it is losing travel on repeated hits, turn it a little towards the hare to reduce the rebound damping and make the fork ‘faster’.

    b) when you attach the pump to + or – you will get a drop in pressure compared to what you originally set. This should settle though and is purely the air from the fork filling the pump (more volume for the air = less pressure).
    The + volume is a lot bigger than the – volume so the – will take less time to fill (from empty) than the + and will lose a larger amount of pressure than the + as well when you fit the pump as proportionally you are increasing the volume of the – chamber by a larger amount.

    Sorry for the waffle. Hope that makes sense. Someone will have undoubtedly beaten me to it in a far more eloquent manner!!

    billyboy
    Free Member

    I have struggled with Air Revs and Air Pikes and never got them how I wanted. I think the simple truth is that they are not very good suspension forks.

    bigjim
    Full Member

    Have you had a lower lube done yet? makes a huge difference to the small bump performance actually having lube inside the legs rather than the air RS use to lube them!

    scruff
    Free Member

    Also, if you keep adding air to the -VE your travel will start to decrease.

    bigjim
    Full Member

    Also, if you keep adding air to the -VE your travel will start to decrease.

    Yeah I found makeing the -ve higher pressure than the +ve was counterproductive, the part of the initial stroke that would absorb the smaller bumps was lost.

Viewing 40 posts - 1 through 40 (of 49 total)

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