What is what?

[MattR]

Originally Posted by Krasi

So, the front bottom clicker (Pic 2) determines how fast/easy/"softly" the fork compresses, i.e. goes up, right? The "fully seated" position is the hardest setting, i.e. the fork is slower/more difficult/"harder" to compress?

You are almost correct, but made a slight typo above (see my red highlighted words). I will try to describe it another way...
Compression is when the distance between fender and wheel axle gets smaller/less. So, when riding the bike, this is when the wheel travels upward towards the fender or your bike is moving towards the ground (depends on your reference point). In any case, it is when you are squeezing the two ends of the suspension fork or shock together (i.e., compressing). If you continue to compress the fork or shock, you will at some point "bottom out" your suspension and the tire will rub the fender. The extension movement (also called rebound) is the opposite behavior.

Originally Posted by Krasi

The front top clicker (Pic 1) does the same, but for the extension movement of the fork, correct?

And there is no spring preload for the front springs (at least not on my forks)?

You are correct on both questions. While there is no "external" spring preload adjuster (like on KTM SX/XC forks), you can manually change the spring preload. If you remove the forks from the bike and remove the top cap (like you were going to change the fork oil), you can change the length of the plastic spacer that compresses or adds preload to the coil spring. You will have to do some slight disassembly, but the spacer length can be modified. A PVC water pipe from your local hardware store can be used as a substitute (just match up a similar diameter). Personally, I have not changed my front spring preload... only the rear spring preload.

Originally Posted by Krasi

The same applies for the rear shosk too I suppose, but I'll need some help with the slow and fast compression.

I didn't want to provide too many details initially (keep it simple) but you want to learn... so here it goes:

The low and high speed compression adjusters are slightly misleading. The high speed (larger adjuster nut) is not really "high" speed... but rather it controls motion in a "higher" low speed range or mid speed level. Actual high speed changes are really done by a suspension tuner who revalves the piston and staging of the shim discs.

These two compression adjusters (low and high) are only changing the oil flow thru a bypass hole. So, when you turn the adjuster screw or nut fully seated, oil is being restricted from flowing thru this bypass hole. It now has to flow through the piston valving. Think of it as water faucet... when you turn the faucet handle closed/off, then the water stops flowing. For suspension, when you make the oil flow more slowly/more restricted... it makes the suspension motion slower and feels more firm.

Conversely, if you back out these adjusters away from fully seated, then you are "opening" the water faucet. Your suspension now has oil flowing more freely/less restricted, so it makes the suspension motion faster and feel more soft.

Well, this reply is getting a bit wordy now... sorry if I'm rambling.

Just a final note... I mentioned the 2 compression adjusters are like low and "higher" low speed adjusters. The best way to remember these are the following: if you want to help control/adjust small suspension motions (like roots and rocks) you will focus on the low speed screw. If you want to help control/adjust larger suspension motions (like whoops and jumps) you will focus on the high speed screw/large knob.

Also, a word of caution... adjusting the Rebound screw will also have some effect on the low speed "compression" motion. This may confuse you but the rebound adjuster controls oil flow thru the center of the shock rod (bypass hole). The center of the shock rod (bypass hole) is also active during compression motion. So, a rebound screw adjustment may also need to be combined with a low speed compression screw adjustment to counteract its effect. Sorry if this just confused everyone... but this is something to consider if you are making a rebound damping change... so only make small changes like 1-2 clicks of the rebound screw. Ride the bike over the same terrain, then make another minor adjustment, etc..

Hope this helps!

[twowheels]

A couple points to add to Matt's description

Originally Posted by MattR

The low and high speed compression adjusters are slightly misleading. The high speed (larger adjuster nut) is not really "high" speed... but rather it controls motion in a "higher" low speed range or mid speed level. Actual high speed changes are really done by a suspension tuner who revalves the piston and staging of the shim discs. This is largely true. The compression adjusters are working on a valve dealing with fluid displaced by the shock shaft into the reservoir as the shock compresses. The compression stack in the shock body is dealing with fluid moving from one side of the piston to the other. The shaft and the piston obviously move at the same speed, but the fluid velocity is determined by the volume flow divided by the area the fluid travels through. Port sizes, both on the shock piston and between the shock and reservoir determine the actual fluid velocity through each component. The compression stack on the shock piston can have low, medium, and high speed damping elements, but they are not adjustable without disassembling the shock.

These two compression adjusters (low and high) are only changing the oil flow thru a bypass hole. So, when you turn the adjuster screw or nut fully seated, oil is being restricted from flowing thru this bypass hole. It now has to flow through the piston valving. Think of it as water faucet... when you turn the faucet handle closed/off, then the water stops flowing. For suspension, when you make the oil flow more slowly/more restricted... it makes the suspension motion slower and feels more firm. On recent shocks, the low speed compression adjuster is a needle jet, much like a fuel screw or the rebound adjuster. The high speed adjuster actually works on a spring against the compression valve shims, so adding high speed is actually preloading the valve stack making it more resistant to fluid flow into the reservoir.

How do you know if you should tune using the high or low speed compression adjuster? Consider the shock shaft speed, not the motorcycle speed. For a given forward speed, if the wheel has to climb this / the shaft speed is slower than if it has to climb this |. Rolling whoops and G-outs would be considered "low speed" events. Roots, square edged bumps, and jump landings are typically considered "high speed".

A note of caution: The displaced fluid wants to take the path of least resistance. If you crank down on your high speed compression, you're forcing more of the fluid through the low speed port, and you can easily end up with choked flow or orifice damping. The overall damping is a function of the interaction of both flow paths.

[nick790]

So how would you set fast/slow speed adjusted?

Is there a correct order to do it in?

What are we looking to get from each adjuster and in what conditions?

[twowheels]

Originally Posted by nick790

So how would you set fast/slow speed adjusted?

Is there a correct order to do it in?

What are we looking to get from each adjuster and in what conditions?

The short course goes like this -

* make sure your bearings are in good shape, your linkage is lubed, your shocks and forks are reasonably fresh, your tires are adjusted to proper inflation, and your axle is in the middle of its adjustment range.
* measure race sag, adjusting if necessary (see separate posts for proper values). Confirm static sag is in range. If not, install a stiffer or softer spring as appropriate and repeat the process.
* start with the clickers (rebound and slow comp) in the middle of the range, as with the high speed comp knob or adjuster
* warm up yourself and the bike
* if at all possible have someone else watch what the bike is doing and take notes. Ride a small loop a couple of times between each adjustment. Ride at the pace you normally ride or race at!
* adjust one clicker at a time, using large adjustments at first, then narrowing down on your final setting. Remember that every adjustment will affect the function of the others, so this is an iterative process
* adjust the rebound damping first, dialing in enough that you don't bounce after dropping off a small curb. Lighter rebound tends to be best, so use just enough to control the "springy-ness" of the bike. Too much will lead to packing and sensations of harshness as if there were too much compression damping
* attempt to ride over the same set of roots or square edged bumps at a consistent speed, dialing out enough high speed compression to eliminate harshness while still controlling pitch. Try a jump to see if you've created a bottoming issue. If so, dial in more damping.
* ride through some rolling whoops at speed and watch behavior of the bike on jump faces. If you're bottoming in these cases you need more low speed compression.
* look at your notes to make sure you've headed in the right direction and toward your optimum ride
* if you think you've got the ride dialed, go on a longer loop to see how it all comes together
* if your bike is still not behaving as you think it should, carefully craft a description of what it's doing under what conditions and what settings you ended up with, and then dig into the internals

Hope that helps.

[nick790]

Thanks,

Trying to get my sachs shock to feel like my old ohlins one.