suspension-i am still confused, so back to basics?

[dhkid]

ok guys, have a slightly better understanding over suspension after a few long threads here about lsc and stuff. also over the summer i re shimmed my shox a few times to get it where i liked it, experimenting with some wacky set ups along the way.


what i changed in my shox, first of all was to drop the oil weight to 7.5 (from the fox standard 10wt) i liked it, rebound was faster and i couldn't feel the boost valve click so much when in pro pedal mode.

then i wanted even faster rebound, so i went down to 5wt. but then there wasn't enough compression, and i didn't like how the shox felt when i used more air pressure to compensate for it.
lesson learn, going to the extrems with oil weight isn't really a good thing. :poster_oops:

then i went back to 7.5wt and re shimmed the main compression shim stack. i made a two stage shim stack, with very very little low speed compression. it was really lively, i sorta liked it. but on the hard fast hits it would use too much travel and the ride was getting really harsh. maybe i should have changed my sag to test that set up more.
lesson learnt, low speed compression is really important.

now its back to 7.5wt and the shim stack nearly stock. still not happy with it tho.


anyways, what i am really confused about is high speed bumps. mainly big roots and stuff like that at speed. what i know is you want as little possible high speed compression so that the wheel can move out of the obstacles way asap. (while on that point, why do we need HSC anyways? since the highest shaft speeds come from high speed bumps, not drops and jumps) BUT we also want LSC so that the suspension doesn't wallow and sink deep into the travel. staying high in the travel, hence the force needed to move the wheel out of the way will be less coz the spring will be less compressed.

SO, is the right amount of LSC the max you can run with out it interfering with the ride over high speed bumps but enough to keep the bike stabel under braking and in berms ect? coz i have haveing a really hard time finding that 'right amount'.

[dhkid]

the more i think about it, the more i wish i could have gotten the 5th element shox tuned the way i would like it. it was just giving a tad too much compression damping for my taste. maybe i could get a small shim to hold open the CV slightly to give less damping. i think its got to do with the low leverage ratio of my bike and the low weight of the rider. :(

arrhh, i am pissed off, feel like saving up and sending my shox to push and finally getting this over with.

[nugget]

It sounds like you need a new Iron Horse Sunday. : )

[pelo]

I´ve done changes just like you to my shock. It´s really hard to know how to tune it...
Maybe you had to much ramp up whith the lighter shimming? How about staying with the lighter shimming or standard shimming and do some changes further in to the shimstack (piston). I know some put a small diameter shim between the two shims closest to the piston to make it more active and blow off easier.(?)
I´ve tried to remove the propedal as much as possible to get it more active and at the same time try to make as stable as I like it by tuning the shimstack.
I have no idea how to do it, just taking it step by step and try to learn some really strange things in life... heh...:rolleyes:

[dhkid]

nugget, back off..:P i would have loved to try your bike down the track i rode yesterday tho.

pelo- what you mean by putting a smaller shim under a big shim is basically a two stage shim stack. it sucked balls. i dont quite understand what you mean by saying changing the shims, coz all the shims are on the main shim stack, aka the piston.

at one point i was all for getting rid of the propedal and low speed compression to make the ride lively but i found that low speed compression is really important.

[pelo]

Ok, two stage shimstack, sorry not too familiar with all the terms, thanks.

I was thinking of maybe try getting some spare shims with another diameter or thickness to change for the ones in your current shimstack?

Yea, low speed compression might be good after all...

[freakrock]

it seems to me that what you are trying to achieve with your dhx is a rocco with 2.5wt oil in it.

[Udi]

You asked why you need HSC... I think first you need to understand what HSC is.

HSC is simply a reduction of LSC. In a ported damper (imagine you had a needle valve adjusting LSC port size, which is pretty common, but the shim stack was locked closed) as shaft speed increases, damping increases progressively.

That's where some sort of variable aperture mechanism (shim stack, motion control, sprung valve) comes into play - this can allow that progressive damping curve to become linear or regressive to provide a reduced amount of damping as shaft speeds increase.

Now if you had a blow-off mechanism that made the amount of damping zero at a certain shaft speed, you would run into issues. If you hit a corner / g-out that created a shaft speed fast enough to reach that HSC "threshold" (which isn't uncommon with a correctly tuned compression damper) you'd have the suspension diving hardcore in those sections of the track. You'd also run into issues with the suspension starting to sit deeper into the travel over consecutive impacts.

Also when the damper works, LSC/HSC aren't two completely seperate entities, together they form a smooth curve and there will always be some overlap.

[dhkid]

Also when the damper works, LSC/HSC aren't two completely seperate entities, together they form a smooth curve and there will always be some overlap.

i understand that, but what i though was an ideal (which i am probably wrong) was to have as much LSC as you can to keep the ride stable and pretty much no HSC? of course when it comes to a main piston shim stack that may be hard to quantify in terms of tuning.

but just say like your boxxer, the motion control handles most of the LSC and the shim stack handles the HSC right? you tuned yours to have loads of LSC with a lower blow off threshold and removed the shim stack. and you prefer it that way dont you?

so a comparable setting for my 40 would be as much LSC as i want, right now about 7 clicks, and with my HSC open all the way?

[davep]

i understand that, but what i though was an ideal (which i am probably wrong) was to have as much LSC as you can to keep the ride stable and pretty much no HSC? of course when it comes to a main piston shim stack that may be hard to quantify in terms of tuning.

but just say like your boxxer, the motion control handles most of the LSC and the shim stack handles the HSC right? you tuned yours to have loads of LSC with a lower blow off threshold and removed the shim stack. and you prefer it that way dont you?

so a comparable setting for my 40 would be as much LSC as i want, right now about 7 clicks, and with my HSC open all the way?

To do this, you need some way for the lsc to 'blow off'. A shim stack can do this, but only to a certain extent. the shims can only deflect so much. Have you tried to put some kind of spring behind the main (first) shim? Basicly pre-laod the shim that closes the ports in the piston, giving LSC. The spring will then compress allowing the shim to move far away from the piston (when pressures increase)...opening up the HSC, mush more that the shim could if it had to bend.

Opening up the piston passages should help as well. The first shim will still close them off for LSC, but when open, more oil will flow with less constriction due to the larger passageways.

PS, let me know if you need some more shims....I Have a full set of DHX shims sittting around.

[dhkid]

thats what i am sort of confused about, would it be good to have loads of LSC, then be really regressive, in that case having very little HSC? or what?

davep, i did try something along what you mentioned. i put a smaller shim behind the first big shim on the shim stack. the shox was really active, and had way to little lsc. and rode way to low in its travel. i might try it again tho, but with more bigger shims in front of it.

how much do you want for the shims, i am interested.

[davep]

thats what i am sort of confused about, would it be good to have loads of LSC, then be really regressive, in that case having very little HSC? or what?

davep, i did try something along what you mentioned. i put a smaller shim behind the first big shim on the shim stack. the shox was really active, and had way to little lsc. and rode way to low in its travel. i might try it again tho, but with more bigger shims in front of it.

how much do you want for the shims, i am interested.

They are yours if you want them. I had push do a DHX that was on a bike that subsequently was stollen. They are the original ones that push returned with my shock. Without the shock, I have no need for them.

They should fit in an simple envelope...cant be too much to mail. Are you in the UK or Malaysia currently?

[nugget]

dhkid,

I think u should really start saving up and send the shock to a custom tuner. Save those pounds, their the biggest dollar. Everywhere u go, anything is cheap. (compared to SGD or the Ringgit) :)

[dhkid]

ian- i could afford if i want to, but i would rather do it my self. and i know i will never get as good as they have done. but its not make me win races.

[nugget]

Adam

Uhh huh.. But u know deep down inside, u would want 2 shocks, one thats tuned and ones that u can play around with. haha.

Anyways, my DHX now feels insanly good. Its all broke-in now.. Feels good, Now to work on the 40.

:)

Laters.

[dhkid]

i know, which is what i sorta did. i had a dhx which (at the time) i was happy with. and i worked on an old 5th element. which i still use now, but that made me realized that i wasn't all too happy with the dhx.:poster_oops: