All other things equal, which is preferable, a soft shim stack with HSC preload, or a firm shim stack with zero preload?
Preloaded Shim Stack vs Non Preloaded
nmxtrdr
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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.
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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.
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.
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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.
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)
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.
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.
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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.
Less extreme preloading moderates all those effects but most forks and shocks seem to go for the extreme end to really bring the suck.
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
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17,486 Posts
If the low speed bleed is too large then you can close it down with the LSC dial......
That probably depends on the damper, right...
faulty charger 2.1?
Hello, i own a lyrik ultimate since a few weeks,but something seems to be wrong. i cant feel any difference in between the full closed settings and/or the full open settings. Not on the parkong lot, nor on a rooty downhill section. went to winterberg bikepark last week, and did a few runs with...
www.mtbr.com
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There's one common exception and it looks like you've found it. But it doesn't have a huge open LSC port to start with. The Charger 1 is a good example of a really big LSC path that opens all the way.That probably depends on the damper, right...
faulty charger 2.1?
Hello, i own a lyrik ultimate since a few weeks,but something seems to be wrong. i cant feel any difference in between the full closed settings and/or the full open settings. Not on the parkong lot, nor on a rooty downhill section. went to winterberg bikepark last week, and did a few runs with...
Mezzer
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17,486 Posts
Low speed bleed in the Mezzer is the size it should be. It's designed to choke out and not have much influence past chassis control speeds. Getting the compression shim stack right is always the key to happiness.
Changing the shim stack tomorrow. A bit of research has turned up conflicting info - shocking.
Will replacing the Dougal 12mm compression shim with a 10mm shim increase or decrease damping?
I was thinking decrease, but I could see it being less initially while being more restrictive at highest velocities.
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17,486 Posts
In a Mezzer you get the same reduction in stiffness again from replacing the 17.5mm to 12mm as removing the 12mm.
Going from 12mm to 10mm you likely won't even feel it.
Thanks.
So, if 20-17.5-12 was a tad stiff, and 20-17.5 is too soft, what would you suggest as a half way point?
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17,486 Posts
More air.
Gotcha.
I don't tune by sag, but I'm at less than 20% already.
I will try the 10mm shim.
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17,486 Posts
Last time I measured sag it was something like 16%!
Nothing to lose by experimenting, go for it. I haven't tried to measure out any shim stacks in between those three (2x17.5, 1x17.x and 1x12, 1x 17.5mm).
Think I'm at 16% also.
I am approximately 16% also.
Went with a 14mm shim instead of 10. Clamping shim (if that's the thicker ring between shim stack and backing) looks to be 10mm od. If I have visualized the stack correctly, 14mm will yield a softer stack than 12mm. We shall see.
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