Which is better, a sports car or a 4wd? Each has a purpose. One would be more suited for a cross country bike that you want to limit pedal bob, the other to a dirt jump bike. You also have to take into account the spring being used, as the damper and spring work together.

 

C - zero preload shim stack with pre-loaded clamp shim.

If you want user adjustable HSC, a spring loaded stack is your primary option. Fox does have their adjustable stack setup though as well.

A stack built for you/your bike with a LSC bleed adjuster will probably give you a better result then a generic HSC adjuster, provided the tuner knows what they are doing.

 

I was thinking about this yesterday on my ride.

Preloaded compression stacks that require a significant amount of force to activate only open AFTER the bump has been transferred, effectively. This is the whole problem with the "platform" idea, using a threshold value to "activate". It seems then that what they are really doing is attempting to dampen out the resulting mass acceleration from your body that is attempting to resist or displaced by the spike, but not so much the bump itself. I think the preloaded stack is a cheap/easy way to increase the pedaling/efficiency without having to use the proper HSC/LSC flow rates and damping that would provide decent low-speed stability and awesome high speed bump absorption. As said above, preloading gives a little "adjustability" if that's what your adjuster is doing...but IME, that range of adjustment is really really narrow and not very useful (which fox has realized and attempted to fix with the Grip2).

Then there's preloaded HSR stacks. Not sure why anyone would choose this, it would seem to always spike.

 

Depends on what you are after, if you want a firm, platformy feel then maybe a preloaded stack will be best but personally given the option I would almost always use a non-preloaded stack.

BUT

its not the only factor, it does depend a lot on piston design. Large, wide ports often won’t generate enough compression damping without a preloaded stack so you will have to compromise something in that case.
There is also a big difference between a dished/stepped piston and flat piston with a ring shim. Broadly speaking a stepped piston will always have a digressive damping characteristic even if you remove most of the preload, while a flat piston with ring shim can still have a mostly linear or even progressive damping curve, once you include the freebleed (eg a rock shox mon plus rebound)

 

Thanks for the replies.

I am playing with different compression shim stack configurations on my fork damper. The most recent change made to the shim stack softened it to the point of needing to add significant HSC to attain a similar feeling of support during parking lot bounce test. Real world trail feel is also similar except for large square edge hits which are causing spiking/deflection.

Trails I frequent are mostly rough and chunky, but I was thinking having some HSC adjustment range would be useful as opposed to being run open all the time. Sounds like I will be better off tuning the stack to be run with HSC open.

 

What damper is it? The piston design limits things a lot, also if the low speed bleed is too large and effects the overall damping force too much then you will also be restricted as too how much change you can make

 

Preloading in the extreme makes low speed damping really harsh, creates a spike in compression forces on every sharp impact and provides less HSC than you would otherwise get.

Less extreme preloading moderates all those effects but most forks and shocks seem to go for the extreme end to really bring the suck.

 

For a small percentage of riders that are looking to invest (spend money) to get things working properly on the trails, when it comes to the newer RS forks, you have two options.

1. Have it serviced by a shop familiar with custom tuning of the damper. It can be corrected. However if this isn't an option for you...

2. HC97 from Push. It's not an install I would consider novice-friendly but the differences are substantial and when tuned properly (as with option #1) can provide similar results on the trail.

I'm not a fan of the VVC Fox dampers and I will gladly recommend another shop who's willing to take them in for proper tuning.

 

So, for heavier riders trying to make the most of an off-the-shelf tune, they’re going to have to resort to more HSC preload to approximate their needs. But, they’d be better served with a stiffer stack and preload all the way out if the option were available?

 

Yes.

 

Sorry to revive this thread, i have a fox shock with compression stack CMSS, or comp med split stack and i don't understand the purpose of the split stack.

question is: is this the same thing as a ring shim that preloads the first two shims (i thought ring shims preloaded the outside diameter?) i don't understand. shock came off a 2022 trance X 145mm trail bike.

SEE shim #3 off the valve, the first "valve: metric" shim. it's about .004in thick. the NON split-stack CM stack is here: https://www.ridefox.com/fox17/img/help/page1132-CPJ1/805-05-511-KIT.jpg

also, oddly Fox doesn't seem to have a FIRM stack for this shock, just CM+. wonder why? is it compensated for by a different base valve setting maybe?

 

That's a two stage stack. So it's more progressive and generates more damping with increasing speed than a linear stack will.

 

Thank you. So this shock has progressive comp and digressive (preloaded) rebound. Seems odd to pair the two but maybe giant engineers are onto something idk..

 

Dunno what they're on TBH. Preloaded rebound makes you choose between stability or traction.

 

Actually the only parts which me and the article both commented on are in agreeance.
And in the words of the article that is that softer low speed rebound causes chassis instability. Or in my words that firmer low speed rebound causes increased chassis stability.

The other part about compliance is just that. It makes no mention of an increase or decrease to traction.

 

This is the beauty of human brain. We read the same article with different takeaway!

Elaborating mine below.

There is only one spring, but the mass could be the human + bike in a jump landing scenario, or the unsprung weight in a rock garden scenario. My takeaway from the reStackor article is to manage landing (deep stroke) with HSR, and manage the rock garden (shallow stroke) with LSR. It’s a deliberate tradeoff I think makes sense for most DH race. The side effect is human body input is underdamped for LSR, and the article manages that with stiff compression at very low shaft speed (sec) to catch the overshoot passing the sag point. I don’t read “using more LSR to improve chassis stability.”

The tuning you mentioned only makes sense to me in a four wheel race track scenario. The antiroll bar acts as a very stiff spring and its rebound has to be controlled out of a corner. It’s like using more LSR to manage cornering roll rebound (w.r.t. antiroll bar) and use HSR to manage all other road bump rebound (w.r.t. suspension spring).

 

Reading this stuff gives me the sense a lot of folks just want to push the bike out in front of them, stiffen their limbs, and hope for the best. But, I'm a weirdo who couldn't give a fvck about full travel and thinks running the HSC wide open on the Mezzer turns it into hot garbage 😁