[Closed] Setting up a DHX2/Damping physics

High speed rebound is only going to affect the shock close to full travel. Setting the LSR is easy with the curb method. Setting the LSC shouldn't take long either. HSC will require some big hits normally.

If you use the cane creek app it helps quite a lot for setting it up.

What is the curb method?

Ride off a curb and make sure the rebound feels goldilocks

I do wish shock companies would use the term amplitude instead of speed. High speed to me is actually high amplitude in shock tuning; now most of the time the faster the shock shaft is moving the deeper into travel it's likely to go but it just makes more sense to my physicist brain. So the "low" speed adjusters are for smaller bumps and the high speed adjusters are for bigger bumps.

No idea about pro tunes though.

I've seen a lot of pro tunes or tunes that have been suggested by people like Mojo to bloggers - that are really quite extreme in comparison to the base settings recommended by Fox.

And then the majority of us "average Joe's" end up running tunes quite a bit more supple than Fox's base settings too! There's a lot of personal preference still to shock setup...

The HSR was the one element I found I couldn't get at all dialled until I actually got out and rode the bike on some bigger terrain. Put simply, you don't notice or feel it at all until you really need it. Coming out of a bombhole, up to a lip, which I took off, but at the same time I discovered just how little HSR I had as the back tried to pogo me off the bike on that first ride! The LSR is what you feel all the time normally, and is what any other shock comes with for adjustment. HSR is factory set in every other shock and fork.

The compression settings I was advised by the Mojo tech guy to ignore Fox's recommended settings. My Evil Wreckoning is a lot more pedal friendly and has a lot more ramp up built into the design than most bikes. He said to wind the adjusters all the way out, then bring them in one click at a time to suit.

It's a fairly tricky shock to setup, and first ride or two out you can be thinking "oh my god, what have I done, this shock is crap" for some time. Stick with it though, when you finally find the sweet spot, it's really rather good.

Cheers Mboy. Ive tuned HSC and LSC damper settings before - but never HSR.

Thanks for the advice.

So the "low" speed adjusters are for smaller bumps and the high speed adjusters are for bigger bumps.

Shaft speeds could be quite high on some small bumps though, could they not? Hence why the low speed adjusters can cause the shock to choke, as therea not enough time for the high speed circuits to open right?

But yeah, amplitude seems a better description.

He said to wind the adjusters all the way out, then bring them in one click at a time to suit.

It's just common sense isn't it really, adjust it untill it feels good rather than everyone asking other people what they run or a generic base tune that is never going to be right for everyone

It's just common sense isn't it really

From what I've seen of the damping circuits high speed low amplitude hits don't push the stock far enough into the travel for the "high speed" circuits as which circuit is being used depends on travel. Hence my preference for amplitude but happy to be proved wrong.

I cant comment on the DHX specifically but to clear up a few things...

Speed sensitive is a bit of a pojntless description these days as any shock with a shim stack is speed sensitive (Which is basically anything worth owning). In almost all shocks low speed is a bypass for the high speed stack, and you adjust the amount of oil that can pass through that bypass using the low speed control. The more low speed you wind on, the less oil that can flow around the high speed stack. This will have the effect of slowing the shock movement on low speed hits where the oil pressure isn't high enough to open the high speed stack, but also to reduce the shaft velocity at which the high speed stack takes effect. By running the low speed pretty closed and the high speed pretty open, you're moving the damping more quickly from a metered port to a shim stack, the latter providing a more consistent damping across a wider range of shaft speeds.

Position sensitive damping is pretty common on many shocks, either as low speed pedal platforms, or deep stroke rebound bypasses, but thats where amplitude of a hit ends its effect as a rule, everything else is generally controlled by shaft speed, which can be as fast at the start of the stroke as it is at the end (and also varies depending on frame design).

When tuning its important to remember that low speed is also in effect at high speed, so high speed damping is the cumulative effect of your low speed and high speed damping settings (in most shocks).

Shocks choking is normally the effect caused by insufficient shaft speed to open the high speed stack, but too much flow for the low speed to cope with, big steps in the stack tune. Its not so much a timing issue as a gap in the tune that means there is a point in the shaft speed thats not properly catered for. It can also be an effect of using flow control pistons on shim stacks that are set too firm on their blow off, having the same effect. or indeed using just flow pistons on their own (like in cheap forks) which have no effective means of dishing out the right amount of damping at the right speed.

Some shocks will have a second high speed compression stack for really high speed hits, which you cant mess with easily. Again combos of the adjustable LSC and HSC might leave you with a choking shock if you aren't careful as you might find that you get gaps in your tune.

Mid stroke damping is always the hardest to get right - the transition from the flow port for low speed onto the stack. It can also be counter intuitive too. For example you might find you have insufficient rebound to control a mid stroke bouncy feeling, but the solution is normally to [i]back off[/i] the HSR whether using an adjuster or tuning the shim stack, in order that you can add LSR to control that wallowy feeling without the shock being too slow to recover under fast hits.

Awesome post Ben! Cheers mate, these are the kinds of informative posts I'd love to see more of in the mountain bike world.

If you haven't already done so, watch all the Vorsprung Suspension Tech Tuesday videos.

Low and high speed circuits are never truly independent, so you can't compare settings on one parameter unless all the other parameters (including psi and linkage kinematics) are the same.

High and low speed should not be renamed high and low amplitude - it relates to pressure gradients across the damping elements and they are mostly a product of damper shaft velocity.

Changing the low speed parameters will affect the high speed parameters because the knee of the curve (where the circuits swap - or combine in most cases) shifts, not just the gradient of that part of the curve.

So he told you to turn off the damping then ride it while slowly turning it back on until it felt ok.
#Groundbreaking#

If I didn't know better, I'd think you were trolling me on purpose! 🙄

You missed the point that I was making anyway, which rather than starting with Fox's recommended settings which seemed miles off, speaking to the tech guy at Mojo he recommended ignoring those settings completely and starting With the compression adjusters wound fully out... Based upon, you've guessed it, his experience!

Informative post benpinnick, makes a lot of sense... When you first start fiddling with the X2 shock it's a case of trying to work out where the low speed adjustment ends, and where the high speed adjustment begins. I had a few moments on the first 2 or 3 rides with the shock when it wasn't fully dialled in to my liking, having made adjustments that I thought would improve the ride but found out to the contrary...

No Mark I was just pointing out you were stating the bleeding obvious but don't let your paranoia get to you. 😕
BTW you might find the MOJO guys can be a bit more specific when they watch you ride and help you rather than just tell you stuff you should already know...

I had a few moments on the first 2 or 3 rides with the shock when it wasn't fully dialled in to my liking, having made adjustments that I thought would improve the ride but found out to the contrary...

I think Stu has it in for mojo! 😆

Not at all Tom.
Paul and Toby from MOJO have both been very helpful when I've been out with them.
Just that the way Mboy talks on here I'd expect him to already know that what he was told was a standard answer...

That tought you so much more than a kind of fob off comment from someone else.

Yes, but the brown stains in my shorts tell me I'd have preferred to have known before hand... (This was on the rebound settings by the way, trying to work out where HSR and LSR took over from each other)

I already know to start with a base setting, then make one click adjustments Stu, again that wasn't the point. Normally the manufacturers base settings are somewhere close, the point was that this really wasn't the case with the X2 on my bike. I'm not running the compression adjusters fully wound out now, but they're much closer to full out than they are the factory recommended settings...

BTW you might find the MOJO guys can be a bit more specific when they watch you ride and help you

You would imagine so for sure... Haven't been afforded that luxury yet. Bumped into a lad down Staunton yesterday with a new Trek Slash 29er, said he bumped into Porter in the car park 2 weeks prior (I saw him out and about too to be fair) who got chatting with him, then rode together for a bit and he made some tweaks to his shock settings for him then and there...