S18 Suspension Chart -- is it garbage?

[SoleCycle]

Is there an unofficial chart that people are actually using? I'm looking at the official Suspension Settings Chart and it looks rather unreliable/unusable.

In my attempt to learn about setting the suspension, most guides for MTB air shocks suggest that the sag should be the first thing to set by pressurizing the top (positive) chamber. A typical starting point is for the Sag is suggested to be around 25% of the shock's piston travel from the unloaded position. According to specs, the stock shock has a piston travel of 57mm. 25% of that would be a Sag of about 14mm.

For a 65kg person who prefers extreme terrain, the chart suggest a Sag of up to 120 cm. That's almost 4 feet for us Muricans. What could they possibly be referring to? I would not trust any engineering chart that exhibits such a fundamental failure of getting the basic units wrong.

But even if they meant to say 120 millimeters instead of centimeters, that's still impossible. Could they seriously be two orders of magnitude off? The only numbers that might make sense is if we move the decimal over two places so that 120 cm becomes 1.2 cm, which is 12 mm. If that is what it's supposed to be, man... what an embarrassing blunder!

The second things that makes me suspicious is that Sag isn't supposed to vary by rider weight. From my reading, Sag is chosen for terrain and riding style. A light person and a heavy person both would want around 30% Sag if they're doing jumps. Each of them would simply use different pressures to achieve 30% Sag, based on their weight.

[daniel1234]

I recommending cheap coil shock ala RCP-2S / exe shock e.t.c. ...  shock itself isn't strong enough for EUC . I was tinkering too much with it until it started losing pressure - not worth of your time !

[UniVehje]

The way I see that chart is that it's a typical chinese way of doing things. You know, the same way they make our vehicles. Someone had a task of making a chart and they put something together that looked like a chart and called it "good enough." Then they just checked the task done on the list and moved on. Nobody bothered to check the quality and once it's done, there's nobody willing to make a better version without someone budgeting funds to do so. The wheel is selling well enough with that chart anyway. 

Obviously the units are completely wrong and whoever made it probably just looked at first result on google and extrapolated from that in a pirated copy of Excel. I would disregard that chart and use the knowledge on this forum to set the suspension. Go with the 25-30 % for sag and then experiment with it until you find a nice setting. 

[FinRider]

48 minutes ago, UniVehje said:

The way I see that chart is that it's a typical chinese way of doing things. You know, the same way they make our vehicles. Someone had a task of making a chart and they put something together that looked like a chart and called it "good enough." Then they just checked the task done on the list and moved on. Nobody bothered to check the quality and once it's done, there's nobody willing to make a better version without someone budgeting funds to do so. The wheel is selling well enough with that chart anyway. 

Obviously the units are completely wrong and whoever made it probably just looked at first result on google and extrapolated from that in a pirated copy of Excel. I would disregard that chart and use the knowledge on this forum to set the suspension. Go with the 25-30 % for sag and then experiment with it until you find a nice setting. 

There are several charts floating around, the "official KS" chart being one of them. As stated, the chart is flawed, not to mentioned the method they use with the block between the pipes when inflating and putting in the pressure. For me it was a trial and error procedure. All the early trials were useless as the suspension was seriously binding. Once I had that issue resolved with the suspension overhaul, I started tinkering and found settings that are right for my wheel. Thats the other parameter that needs to be taken into account, all these wheels seem to be "individual" and no two are alike... so the pressure I use may not work on your wheel even if we would have the same weight.

My recommendation would be to just trial and error it to find the pressures that feel right to you. Just for information, I have ended up at 200 / 80 (I do not use the block) as my go to setting. I check it every few months and I see only a slight drop in negative pressure from time to time, which most likely is attributed to the escape of pressure when you detach the pump hose.

 

[SoleCycle]

I think that years of western schooling has instilled a more trusting perception of technical charts. Thanks for the replies and the sanity check.

[Tawpie]

Also keep in mind that you can find all sorts of things on the internet, charts and specs etc. It's pretty much impossible to verify that "this one" is the latest, most correct and not a proof copy for colors and spacing and typos. And even then, it's rare to see much of anything actually gets updated to make corrections... once the product is out there, few companies care anymore.

Definitely follow @FinRider's advice and go with what gives you the ride feel you are looking for, the chart is a hint at possibe places to start. You must experiment. The only thing the block does is make sure the suspension is in the same specific position each time you pressurize it so that you can use the pressure reading as a reference. The actual numbers don't really matter, you're after a certain result!

[Wrd]

The chart’s a bit wonky but it’s best I’ve found. I don’t know what I’m doing but this is what I’ve come up with.

I’m like 160lb and ride rough trails; My gear probably adds an extra 30lbs.

Here are my steps:

Start empty
- Remove the caps (remember the cap order cause mine are like that)
- Empty both chambers

Filling
I screw on a 90 degree valve adapter (TopPeak: https://a.co/d/fIOVhp9) so the hose doesn’t get impinged with the upper chamber)
- Fill the bottom chamber 160psi
- Fill the top chamber 235psi

Set rebound
- Set the dial to about midway.

Replace the caps. 

Enjoy your shock!

If you don’t have a 90 degree valve adapter you can start the 2nd filling step (upper chamber) after 
- turning on the wheel;
- sitting on it so the upper chamber stays exposed
- Lock the shock to slow it down
- Over fill (I went to to 260 - 300psi) keeping all your weight on it.
- remove the pump hose, but keep your weight on the wheel and watch your fingers!
- stand up

[SoleCycle]

35 minutes ago, Wrd said:

I’m like 160lb and ride rough trails; My gear probably adds an extra 30lbs

We're the same weight and ride similar terrain so I really appreciate you sharing your settings!

[level9]

Here's what I have personally found after much research over the last year (looking at my notes as I haven't had to adjust in quite a while):

Option 1 - Without sitting on the wheel (using valve extender), use settings from the DNM shock manual.

Option 2 - If sitting on the wheel, use the kingsong chart.

 

I had the best luck setting using the first method, dial in 10mm sag, 240lb rider w/ gear. I hop curbs and go down stairs all of the time, hit pot holes, etc. (but no BIG jumps) and no issues.

[mrelwood]

 

On 9/13/2022 at 9:49 AM, Wrd said:

- Fill the bottom chamber 160psi
- Fill the top chamber 235psi

Note that if you fill the negative bottom chamber first, it's pressure will change drastically while you fill the main top chamber. Every time the shock compresses or extends, both pressures change. And for that same very reason...:

 

On 9/13/2022 at 9:49 AM, Wrd said:

- sitting on it so the upper chamber stays exposed

Pumping while sitting on it will give you drastically different results each time.

[Wrd]

On 9/16/2022 at 1:32 PM, mrelwood said:

Note that if you fill the negative bottom chamber first, it's pressure will change drastically while you fill the main top chamber. Every time the shock compresses or extends, both pressures change. And for that same very reason...:

 

Pumping while sitting on it will give you drastically different results each time.

That’s a good point.
With the valve extender there’s no need to sit on it while pumping anymore! I’ll try filling the top chamber first next time.

At least it’s pretty well dialed in at the moment.