trials suspension setup resource?

Discussion in 'Trials' started by ThrottleJock, Mar 16, 2012.

  1. lamotovita

    lamotovita Ageing Adventurer

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    Congratulations Throttlejock. You have found the best resource there is for Trials information, the experienced riders at your local Trials events.
    #21
  2. mung

    mung Been here awhile

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    Best place for fork springs--Marzochi[?] springs are the same as Zoke downhill bicycle fork springs.Stock Raga springs are .30.Bicycle fork springs are available in.20,.30 and.40.I put the .40 in with half the stock preload and they work very nice for my 230 pounds.They only cost 40 bucks for a set at a bicycle shop and they are the same spring. I use 10 wt. oil in compression side and 5wt. in rebound side both at 100 mm from top of tube.My Raga came with an Ohlins[the good one] and springs are available at Ohlins USA for any weight you want for about 42 bucks shipped.Preload--Preloading a spring does not make a spring stiffer.It just makes the initial movement of fork rougher with no gain in overall stiffness.If you want to make a fork work right the spring weight needs to match the persons weight.Good quality springs should not be bothered by being held in tension.Do you release the tension on the valve springs in your truck each night? Do they seem to work ok the next day? Above all,enjoy your riding. Mark
    #22
  3. ThrottleJock

    ThrottleJock Shaved Ape

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    Ahhh now you tell me! I ordered a set of +10% springs from lewisportusa today fit 3 times that$. No matter, I'm excited to ride this bike with working suspension :freaky
    #23
  4. Sting32

    Sting32 Trials Evangelist

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    Well, in "practice" pre loading the spring does make the spring stiffer, for the bike and rider, because even if you map it with a chart, you can measure the difference in the forces it takes to 'move'...

    if no preload leaves you with it taking 40lbs force, to begin movement, for the 1st bit of travel, say 1/2 inch for easy calculations, from there the design of the spring dictates what the exponential rate would be. The gasgas in question, has almost 7 inches of travel gives us 14 points to check the amount of pressure it takes to compress further, using half inch measurements. So, preloading 1/2 is like moving up the chart, it now takes x amount force more at start and the new highest values have moved up a notch, just closer to maximum compression design of the spring, which would be measured just before coil bind. Yeah 10% stiffer design springs, this whole travel would have modified exponentially the rate at which we have to apply weight to move the spring to compress it another inch. So technically, preloading... no it did NOT affect the exponential "rate" of the spring, but it affected the where/range of effective rates we are "using'.

    Lets look at it more, with some fake easy values becuase I'm not an engineer, and dont have real values that would be hard to follow anyhow.

    Lets take the stock spring, and say at rest with stock "preload" in one shock assembly and not counting resistance due to seal and or fluids... this is a paper engineering study... By a person that doesn't like math anyhow... :puke1

    So lets just say and agree for this study, that the stock spring, takes oh about 40 lbs of force to move spring from Static or at rest, to 1/2 inch comression, then next 1/2 inch takes 42lbs, the next takes 45, which creates sort of a bell curve when plotted, that curve is the "exponetial rate" of the spring... So Im not doing a bunch of math, Im painting a picture, so plot in out in your head, and so on for 14 different one half inches. plus we dont ever use that last 2, 1/2 inch measurements designed in the spring (if we dont add too many spacers that is, due to lenght of fork tubes, and what gasgas says about addng preload to the spacers...

    ok? so far?

    So now I add the 1/2 inch preloaders via adding to the spacer:
    I have now made that 1st 1/2 inch move up the graph, and increased how much it takes to now move the spring from static 40 lbs, to the new 42lbs of force of previously plotted 2nd 1/2 inch, everything now overlays up one plotted value or x is now +1. If I add one inch preload, x moves up now 2 spots on the chart.

    OK?

    SO knowing that the 10% stiffer srpings, have a different expontail rate, BUT it is already given, we can take this fake study and draw a conclusion:

    If I take the 10% stiffer spring, you just add 10% to the exponental rates of the spring, so instead of "stock" preload lenghts, being 40 lbs, it is now starting with 10% more or 44 lbs, the next step takes it up faster on forces, so that point #2 went up 10%, so the second 1/2 inch is now 46.4 lbs of forces needed, plot that on the new bell curve, up through almost coil bind, and or until forks cannot move farther, you know up to our 14th 1/2 inch.

    AND,

    if I preload that 10% stiffer spring, you can see it really takes a lot of forces to compress the spring up to the 14th half inch...

    I picked 40 as a guestimate, since we have 2 springs in front, and I can (without even doing math) imagine that 1st values actually is somehwere near 40lbs, since the bikes weigh in at <140 lbs total, maybe 60% of weight is on front, equals 84 lbs? well hell Im not all wet?

    Anyhow, I think if you weigh 200 lbs fully dressed, the pair of 10% stiffer springs, you will HATE them, because with both of them in use, you effectively took even my dumb little study, and doubled it, because you have 2 springs @10% = 20%... Just sayin... FROM MY EXPERIENCE, and I'm anywhere from 10 to 20 lbs heavier ready to ride than you are, 2 10% springs were too much when I was 40 lbs heavier than you.
    #24
  5. mung

    mung Been here awhile

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    I am about 250 ready to ride.With the heavier springs the bike sits higher in the suspension stroke and is at the same time plusher on the little bumps and stiffer on the big bumps.With more preload you would gain on the big bumps but lose plushness on the little stuff. I think that is the advantage of having the correct springs for the riders weight-you have good suspension on both ends of the spectrum.Of course any decent rider is going to kick my fanny no matter how good my suspension is set up.
    #25
  6. Sting32

    Sting32 Trials Evangelist

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    Yep, I like softer setup now, and it was MY OPINION, just sayin...

    when I went below 250 I guess, the bike, especially front tire would "slip" off muddy slippery rocks, or even just stop or attempt to stop me, in dry conditions... This was proven even more to me to be easier at last club event, at damn near same wet conditions, on my bike with softer spring setup... (it is all about how it feels to you, to me yeah, probably more than just slightly you know, it is how it feels and again it is IMHO)...

    Oh and I always used stiffer setup in my forks, just because I HATED even the notion, that front might (all from past expeiences on many bikes) buckle under on a drop, or worse catch skid plate when nobody else was, you know that "Suprise" knock you off balance thing that can really hurt your confidence, lol.

    What I have learned, and seen, that I've apprently always did anyhow, was "help" by unloading suspension whenever I got in situations, so the only thing left was, when you jump up a ledge, for example, but landing area has bumps or garbage, the front tire tended to stop instead of compress and rol over...

    again Im trying to type out about a feeling of a "tendancy" that became apparent to me... now I know, usually I could if had balance and poise to overcome, just unload pressure on bars or whatever, but when wet, why work that much harder, why having to balance harder, and have to make up for too stiff front end...?

    that was my deciding factor anywho... Your milage WILL vary...

    Please keep in mind, Im not tryin to make "wholesale changes" to how you like it. Im talking about that "tiny bit" that tendancy, the reason bikes didnt get to 145lbs or less, overnight since 1975... those little gains, that feel better or what not.
    #26
  7. ThrottleJock

    ThrottleJock Shaved Ape

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    That generally parallels my experience when I move to a stiff-than-oem (and correct-for-my-weight) spring rate too. I'd guess that bikes are targeted at a 150-160lbs rider or thereabouts. I'm 191 w/out gear, probably 205 in boots & a helmet. I have my roadrace bikes set up for 205lbs and they're just about perfect. Anyway, I digress - the thing is, with too-soft stock springs the only thing a fatso like me is to do to try to get in the ballpark of the correct sag is to crank down the preload. Even so, I'm .75-1" deeper in sag than I should be (on this bike in particular), and even if the forks didn't have the bunghoolio-installed spacers which limit travel, I'd be deep into the mid-stroke of the travel when just riding around.. into a harsher range of suspension than I should ideally be, commensurate with the speed I'd be traveling. With a stiffer spring it'll bring me back into the right range, and with oil weight changed to match all of a sudden the suspension will begin to operate like it's supposed to, like it would for that 150-160lbs target rider. In theory.

    Having said all that though, I'll be satisfied just to have full travel back and to stop hearing (and feeling) those scary clunks. My wrists will thank me.
    #27
  8. mung

    mung Been here awhile

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    When you do your spring change I assume you will change the oil? For the clunk I would check that the cartridge rod nut is [was] tight to forkcap and that bolt in bottom of fork is tight.That and a good bleed of the cartridge with new oil and springs should do wonders for the front end. Also my bike [04 300 Raga] was targeted to a gentleman named Adam Raga.I stood next to him at the world round at Donner, California in 1997 and if he weighs 135 pounds that must be with a big dinner and a backpack on.He is a very tiny guy.He came to the middle of my chest.
    #28
  9. Sting32

    Sting32 Trials Evangelist

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    Yep, you will have it sorted I think, my "un needed" worry, why did I worry about someone I dont even know's trouble? Because I am the TRIALS EVANGELIST, lol. My point, and if I knew you better I think I could have risked being lots more "direct" than hoping you might somehow magicaly figure out what I was warning about, with the big old posts...

    Im worried that the springs you have are nackered... way soft due to sinching bikes in trailers and what not... then if you replaced with FRESH NEW "stock" springs, it might fit you better, with even adjusting up to maybe 1/2 inches of spacer added to one or both sides, measured from STOCK spacer size, of which we'd have to look up, or take my bike apart to recall the actual lenght.

    My worry is, from my experience, 2x 10% stiffer than stock springs, for a person who weighs 190 LBS, seems to me going to be an ERROR... ONLY because when I, who was at one time 280 hated 2x10% stiffer than stock springs & stock spacers.... you get me?
    #29
  10. ThrottleJock

    ThrottleJock Shaved Ape

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    Totally, and I appreciate the concern! :) I was thinking that if it turns out that the +10 springs are too much, I can just drop one of the stock springs w/ correct preload spacer back into one of the legs. It'll be good for me to get to know the suspension on this bike a little more anyway so taking it apart a couple of times won't be so bad if that's what it comes down to. Thanks again man, I'll keep you all posted on the results!
    #30
  11. Sting32

    Sting32 Trials Evangelist

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    That is cool :thumb

    Reading your posts, I hope we'll run into each other sometime, you seem to think like me, brewtus, and the gang... Everything is about tweaking it how you like, with help, it goes the right direction. Trials has a long known, maybe unwritten motto though (besides the Bultaco Thmbs up "cemoto" hehehehe). It is an original fact, (IMHO):
    "learning to use new techniques, is grossly and inversly proportional to the time it takes to UNLEARN bad habbits you already use."

    Oh, and DONT FORGET
    Be sure to post up results of your work, Im am sure either now or in the future, this thread could come in handy...
    #31
  12. ThrottleJock

    ThrottleJock Shaved Ape

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    Okay guys, a quick update.

    Yesterday I rebuilt the forks; tore them down, changed the oil, recharged the oil in the cartridges, changed to the +10 springs, set the oil height and stared at the preload spacer for about an hour trying to decide whether I should cut it or not. I decided to bolt it back together.

    It works! A full, glorious 7 inches of travel! Holy cow I didn't know what I was missing. I'm able to ride down hills and ledges and over rocks and things now without slamming metal on metal and cracking my wrists.

    The springs ARE a bit stiff, so I may end up pulling the spacers and trimming a 1/4 inch or so, or I may swap one of the stock springs in to get the spring rate in the middle. It actually feels perfect for the type of training/play riding I do, but it might not be dropping far enough in the stroke to get the traction I need for slow slippery trials comp stuff. I'm getting about 1.5" of sag, which I think is a little short.

    NO complaints though, all in all I'm extremely happy to have working suspension! THanks all for your help.
    #32
  13. Jonny042

    Jonny042 Been here awhile

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    Something to keep in mind when playing with springs, and adjusting for different rider weights, is the fact that only 1/3 of your body weight (under static, ideal, conditions) ends up on the front.

    I took the following measurements on my scale:

    73 pounds front bike empty
    72.8 pounds rear bike empty

    135 (ish) front standing on pegs which means 62 of my 195(ish) body weight ends up on the front suspension, and the rest on the rear. So that means 133 of my body weight is on the rear, so loaded weight should be about 206.

    I take from this that even if you are a REALLY big guy, your body weight contributes a lot more to the action of the rear suspension, and in theory means playing with front spring rates more than a little bit is going to take you outside the optimum range.

    In practice, I found the front end of my 2011 300 Gas Gas to be far too easy to bottom out, and the rear to be too soft. I added a bit of oil (sorry cannot remember how much!!) to each fork leg and swapped from the stock 65 n/mm rear spring to a 75n/mm rear spring to compensate for my weight.

    I think it's perfect now and wouldn't change a thing. Except a new bike is on the way so I have to start all over with the reiger shock!
    #33
  14. laser17

    laser17 Been here awhile

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    The nice thing about the Reiger is that it has adjustable rebound damping control - so when you put on the HD spring, you can tune the shock accordingly (add rebound). Reiger has a shock spring weight chart as well as a fork revalve / oil height guide that comes in very handy. Stu at Jackscycles stocks some of the common HD Reiger springs and has done a couple fork revalves to the Reiger spec as well. The initial feedback seems to be very high. Reiger and GasGas are developing some really neat suspension upgrades. Stu has a new "factory" shock that has High and Low speed compression damping adj. Rebound damping adj, A hydro bump stop setting and a rebound delay adjustment ( a really cool idea for helping advanced trials techniques) . I hope that we will see those upgrades on the 2012 raga bike.
    #34
  15. Jonny042

    Jonny042 Been here awhile

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    Sounds neat! And expensive..... I have seen the weight chart for the spring, and was relieved to see that it validated the spring change I made for my weight on my "old" 300 with the Ohlins shock. My understanding of the new bike (not quite here yet), a 300 "Race" is that it has only one dampening adjustment.

    I have not, however, seen the fork info can you point me at it?

    I will have to get in touch with Stu, is he an email guy or strictly a telephone type? I was quoted $190.00 for a spring, perhaps he has a better source.

    Thanks for the info, Jon
    #35
  16. laser17

    laser17 Been here awhile

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    Hi Jon - Stu is a phone guy. 207-337-1274. Give him a call - i think the new HD fork springs he gets are FAR cheaper than $190 and you are both the same weight -so he can give you the specifics on his forks. I think your right with the shock on the Race. That makes no sense to me as the race should have the top flight shock IMO. Probably works great, but for us big guys who change the spring - the rebound adj.is really nice to have. Other than that - they look like great bikes.
    #36
  17. Jonny042

    Jonny042 Been here awhile

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    Thanks!! I will call him Monday then. I was unclear, the quote I got was 190 for a rear shock spring. So hoping he's got the hookup for a slightly better price we'll see. Sounds like he'll be interested in my suspension mods rather than trying to discourage me like other people seem intent on....

    I have searched for the Reiger info on fork oil/valving - is it available on the web? I also checked the Jacks website and didn't see it but I did find a really neat .pdf file of the "Racing" brochure:D
    #37
  18. laser17

    laser17 Been here awhile

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    Sorry I misunderstood. Im pretty sure the Reiger fork re valving guide is for dealers only - so it's not online. In fact, i think dealers have to purchase it from Reiger. Im not sure of all the prices, but Im positive Stu will save you big money on the shock spring or fork springs - so definitely give him a call. With all the variables with the suspension - its best you have a direct dialog.

    Also - Just to know your not alone in your quest, another friend of mine just up'd the spring on his Raga to a 72.5n-m and loves it for making the bike more lively under him. (he's about 200lbs and an expert rider here in the NE) He feels the forks are fine the way they are. Stu uses a 75n-m on his bikes and wanted better balance between the ft/rr spring/damping rates. I dont think there is a right and wrong here - just what you personally prefer.
    #38
  19. Jonny042

    Jonny042 Been here awhile

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    I called Stu today and we are all set - have ordered springs, front and rear, for the new bike. He and I see exactly eye to eye on suspension setup so I am looking forward to installing them them!

    Stu seems like a stand-up guy and great to talk to, a wealth of knowledge that he seems eager to share.
    #39
  20. Sting32

    Sting32 Trials Evangelist

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    But, Is it possible for you to possibly post the "round figure" (not maybe special price he may or may not have gave you) for the heavier rear spring? I only ever had springs for the old Sachs shocks...

    I mean, for the (lost track, you have the "racing reiger rear" or "Raga reiger rear" dual adjustable, or Ohlins rear shock?

    and another question, if you have the most recent gasgas bike, is the front is still Marzoocchi even on the 2012 bikes right? (ignore spelling).

    thanks.
    #40