rear shock valving and rider weight?

[400man]

Im planning on sending a spare stock rear shock to GT Thunder to be revalved/resprung/etc. for my XC link. Im currently running a shock redone by JET, its a dual rate spring setup. Ive been playing with settings for a while on it, ive had it for about 2 years now. when ever I get my ride height set to how I like it, it makes it way too soft and it likes to bottom out a lot. and I do have the compression adj. on the stiffest setting. and when I tighten the preload to try and stop it from bottoming out as much, my ride height is way higher than I like, and my rear shock feels too stiff and it rides kinda rough then.

So my question is, do they use different valving for different rider weights, or just one type of valving and stiffer or lighter springs? I weigh about 145lbs (an about 150ish with riding gear and stuff). Should I tell them my true weight, or tell em a lil bit extra so that they set it up stiffer, then I can use less preload and anot worry about it bottoming out as easy? does that make sense?

[chronicsmoke]

I could be wrong on this but I think the valve it into a certain weight/rider skill range and the springs are what fine tunes the progression for that valving..

When I had Stadium setting me up we had to go up on the main spring in the back and I had asked it it will affect the valving but he said I was still within the specs so we just went up on the main spring.

Dustin_j is the man to ask around here, maybe he'll chime in if he's online.

[ben300]

I could be wrong on this but I think the valve it into a certain weight/rider skill range and the springs are what fine tunes the progression for that valving..

When I had Stadium setting me up we had to go up on the main spring in the back and I had asked it it will affect the valving but he said I was still within the specs so we just went up on the main spring.

Dustin_j is the man to ask around here, maybe he'll chime in if he's online.


this ^


they have different valving for different rider weights and riding styles. they then use different spring combinations in conjunction with that. so if for say you are maxed out on your compression (which you should never max your compression. its bad for the shock) and when you increase your preload, the shock becomes to still, then id say you need to do one of two different springs. they either need to go slighlty stiffer on your cmpression and retain your springs, or they need to leave the compression, back it off, and then change either your helper or main spring (i believe on a dual rate set up, your main spring does most of the work).


a duel rate set up should act differently than a single rate set up, and note: XC set ups are inherently soft. they bottom out a lot. mine bottoms out quite a bit, but its not to the point where its like constantly bottoming out. also, GT thunder, and Gregs ATV (greg used to work for GTT and thats who i had do my rear shock), are known to make the rear end softer than what you normally would think.


sounds to me like your getting faster:muscle: (so maybe its time for a valving change)

[2001400exrida]

here's some good info on shock setup

https://www.youtube.com/watch?v=wH6JlGNvszg&feature=youtu.be

gt thunder does great work, i have some of their zps front shocks, but i'll tell you that there are other companies out there who seem to be better.

[400man]

cool video, but im still confused a lil bit :o

So basically, I just need a setup for a lil more aggressive riding? I don't really do any kind of big jumps, and just what ever is in the trail in front of me. It does it worst when im riding fast and I hit a wooped out spot or a gully or G-out (I think that's what they call em?)

but what I don't get is when people talk about setting their shocks up and talk about setting the frame on 2x4s so that their frame never bottoms out. when your riding, the ground is never flat.......and usually your in ruts. And when you bottom out in a rut, your frame hits sooner than what you set it for to bottom at, make sense?

[ben300]

cool video, but im still confused a lil bit :o

So basically, I just need a setup for a lil more aggressive riding? I don't really do any kind of big jumps, and just what ever is in the trail in front of me. It does it worst when im riding fast and I hit a wooped out spot or a gully or G-out (I think that's what they call em?)

but what I don't get is when people talk about setting their shocks up and talk about setting the frame on 2x4s so that their frame never bottoms out. when your riding, the ground is never flat.......and usually your in ruts. And when you bottom out in a rut, your frame hits sooner than what you set it for to bottom at, make sense?

the 2x4 measurment is solely for finding the compressed shock lengths for your suspension set up. it has nothing to do with real world bottoming out (unless you bottom out on perfectly flast surface). that 2x4 method is just a static measurement of a compressed shock length. you then give that to the shock builder so that they make sure that when the shock is fully compressed and through its shock stroke, its at that lenght. they then use this on the dyno to tune your shock to your needs.

[KKiowaTJ]

I used to and when I get to my shocks getting done for a rear mx link, Im going to have them valve it for 15lbs more than I weigh with gear. Reason being I like a stiff suspension so im always good to not have to 'dial it in' everywhere unless I need it stiffer. Plus, If you race a mud race like some of the pic's guys have posted, Looks like they gained about 20lbs in mud alone so that there offsets the difference.
The valves can be the same, But its how they are stacked in the shock and the response by the spring is what changes from growing into more aggressiveness on trails and track. Plus having the correct fluid in them makes a world of difference too. Lots of things go into shock building, That's why there are no or not many 'shade tree' shock builders.

[2001400exrida]

The valves can be the same, But its how they are stacked in the shock and the response by the spring is what changes from growing into more aggressiveness on trails and track. Plus having the correct fluid in them makes a world of difference too.
i run air filter oil in my shocks, is that ok? the nitrogen charge is very important too, if you've lost charge you've lost your suspension.

[KKiowaTJ]

i run air filter oil in my shocks, is that ok? the nitrogen charge is very important too, if you've lost charge you've lost your suspension.


If you loose you're nitro charge, Its just a bouncy *** ride with the shock doing nothing but acting like a limiting strap. There is no comp/de-comp.

IMO, For the money and the fact the suspension is what keeps you in the race and still at pace, I would only want quality fluid in my shocks like race tech ultra slick suspension oil. It has anti wear chemistry along with being fade resistant. Along with race tech gold valves, You wont find a more plush ride.

But in all honesty, If I knew a lot about suspensions, Id be making money doing it. I wouldn't think air filter oil would be the best, But could very well be the same thing in a different bottle. Only thing I can say, Is if its working for you and you are happy with it and is not causing harm to the internals, Run it!

[2001400exrida]

i was kidding about the air filter oil, lol. I have no clue what kind of oil has been put into any of my shocks.

[KKiowaTJ]

i was kidding about the air filter oil, lol. I have no clue what kind of oil has been put into any of my shocks.

No worse than watching people add air to their forks with an air compressor letting moisture in. All suspension builders are different and use what they like the best and have the best results. Im sure blinker fluid would be a decent substitute if you are in a pinch lol.

[400man]

so, should I just have them set it up for a 200lb rider, to compensate for the softness?

[Blodg]

I wouldn't exaggerate my weight, just tell them what type of riding you do with a good description of your setup. If you do mostly woods/XC type of riding then you want it soft. If your currently bottoming out on jumps then tell them your proper weight and that you will be doing jumping/mx style riding.

I described my experience, weight, setup, and riding style to GT Thunder and they work perfect. I rode the fall and winter at 10-15 lbs heavier than they were setup for in the spring and they work great. Yes they do bottom out occasionally and the frame hits on rutted areas sometimes but that is a proper setup.

[ben300]

so, should I just have them set it up for a 200lb rider, to compensate for the softness?

just tell laz or whom ever you speak to your weight with gear, and tell that person that your current set up is just a little soft for your like. explain to them your concerns about ride height in regards to compression and preload adjsutment and ultimately tell them you want to be a little stiffer on your set up.




on another note, i saw on FB that derisi is offering a deal now that if you get your stock shocks done by them, they offere free valving upgrades for life. all you have to do is pay for the service fee for shock work. pretty good deal imo.

[dustin_j]

just tell laz or whom ever you speak to your weight with gear, and tell that person that your current set up is just a little soft for your like. explain to them your concerns about ride height in regards to compression and preload adjsutment and ultimately tell them you want to be a little stiffer on your set up.




on another note, i saw on FB that derisi is offering a deal now that if you get your stock shocks done by them, they offere free valving upgrades for life. all you have to do is pay for the service fee for shock work. pretty good deal imo.

Most builders offer some sort of follow up valving changes and support within a reasonable timeframe for either cost of shipping or a fee cheaper than shock service. However, the offer for valving changes a year down the road for the cost of a service is pretty decent.

You want to tell GT Thunder your weight (with gear). Rider weight determines the spring rate to give proper race sag. Then tell him how you are struggling with your current setup being too soft when adjusting ride height. It would help if you measure and could share race sag (it's hard to do just yourself, you really need to have a helper). You want race sag to be 4-5". If you are adjusting your current setup within that range, and still having excessive bottom outs, then compression damping should be increased/stiffened. You don't really need a dual rate rear spring setup with a well designed linkage. The linkage provides the correct progression, so a single rate is good. Front A-arm leverage ratio does not generally change much (little to no progression) with wheel travel, so a multi-rate spring setup is critical in the front.