why such low pressures in the Zeb's?

[Paris Doo]

No matter where you start (higher or lower pressure) try the bracketing method in order to get the desired performance. For example start at 80 and see if you are happy. If it is too hard try 70. If it is still too hard try 60. Then if 60 is too soft try 65. If 65 is still too soft then try 67.5 which would probably be the desired pressure.

Same method could be applied to rebound, damping, spacers etc but make sure to start first with the psi (with everything else fully open).

 

[Plummet]

Hopefully others don’t take this as a good way to set up their fork. It leaves nothing in the tank for an over shoot on a jump, a general fuck up or even riding progression.

I have a 140 fork that I rarely bottom so with your thinking I may as well be on a rigid fork as I set my forks up leaving a little in reserve at any travel.

I hope they do take my advice. It is suspension set up 101. Go test your suspension for small bump compliance, mid range and then at bottom out. If you don't test bottom out haven't correctly set up your suspension.

How do you know what extra amount you have in the tank if you dont test?

Go out and jump off the biggest thing you expect to take on and find the limits of your fork. You should soft bottom on that biggest thing. If you dont test, you dont know what the limit is.

Here's my datum drop. Its about a 12 foot vert step down with a landing not really steep enough. If i soft bottom off this, have good small bump and midrange I am set up perfect for my riding.

Now, as im not hitting harsh 12 foot drops all the time for less crazy riding i am using about 80% of my travel. Then i have another 20% to tank on these big features when I want to take them on and for regular riding i have that bit extra in the tank for stuff ups that you talk about.

So... it is far better to test that bottom out and discover the limit in a controlled manner rather than fining out while crashing or during an error if you have set up your suspension correctly.

 

[irie]

I hope they do take my advice ...

... Then i have another 20% to tank on these big features when I want to take them on and for regular riding i have that bit extra in the tank for stuff ups that you talk about.

Good to know that using perhaps 80% of suspension travel with perhaps 20% "extra in reserve for stuff ups" is a sensible strategy.

 

[RustyIron]

For example start at 80 and see if you are happy. If it is too hard try 70. If it is still too hard try 60. Then if 60 is too soft try 65. If 65 is still too soft then try 67.5 which would probably be the desired pressure.

Whaaaaaaat?
Are you suggesting that decreasing the pressure will provide a softer ride?

 

[Paris Doo]

Whaaaaaaat?
Are you suggesting that decreasing the pressure will provide a softer ride?

What I said was just an example of the bracketing method but yes usually less psi mean plusher ride and more traction until of course you go too low. Of course what is too low or too high depends on your weight, riding style, terrain, fork model etc.

I have a 190 Zeb and I run lower than average psi with faster than average rebound.

 

[Shjay]

What 35-40% sag for your plush ride? Would be running v soft then bung in load of tokens to firm up last bit of travel?

 

[Dave_B]

so that's the other thing, what sag % do you all aim for in your Zeb setup?

 

[Paris Doo]

I care more about achieving the desired ridding performance rather than a specific sag % . Obviously it is not 5% or 50% - it should be around 25% - 30% if I remember correctly and I always try to balance the fork & shock performance.

Running too much sag and then adding volume spacers could reduce the range of useful travel so I prefer a more linear approach but I don't do big jumps or drops anyway.

 

[Plummet]

Good to know that using perhaps 80% of suspension travel with perhaps 20% "extra in reserve for stuff ups" is a sensible strategy.

If I wasn't hitting the big stuff I'd probably change that to 90% for regular riding.

I'm still a firm believer of you should soft bottom on your hardest hit.

 

[ebikerider]

I hope they do take my advice. It is suspension set up 101. Go test your suspension for small bump compliance, mid range and then at bottom out. If you don't test bottom out haven't correctly set up your suspension.

How do you know what extra amount you have in the tank if you dont test?

Go out and jump off the biggest thing you expect to take on and find the limits of your fork. You should soft bottom on that biggest thing. If you dont test, you dont know what the limit is.

Here's my datum drop. Its about a 12 foot vert step down with a landing not really steep enough. If i soft bottom off this, have good small bump and midrange I am set up perfect for my riding.

Now, as im not hitting harsh 12 foot drops all the time for less crazy riding i am using about 80% of my travel. Then i have another 20% to tank on these big features when I want to take them on and for regular riding i have that bit extra in the tank for stuff ups that you talk about.

So... it is far better to test that bottom out and discover the limit in a controlled manner rather than fining out while crashing or during an error if you have set up your suspension correctly.

That's a clearer explanation rather than what you said the last time of how to set your fork up by bottoming it.

 

[Plummet]

That's a clearer explanation rather than what you said the last time of you set your fork up by bottoming it.

But i do set it up by testing bottom out....

 

[RustyIron]

so that's the other thing, what sag % do you all aim for in your Zeb setup?

I like 30%. Don't try to soften up your suspension by increasing sag. Doing so will increase harshness.

 

[High Rock Ruti]

lots of posts on here about users running lower pressure than what the trailhead app suggests. I'm the same. 95Kg rider, 2 tokens, 65psi pressure and very rarely if ever get full travel. (Trailhead suggests 92psi)

why are such low pressures needed in the Zeb's? (I have the latest buttercup version)

High Rock Ruti

I tried all the setting combinations, landed here. 0 tokens 0 Compression some rebound pressure in the 60's. I am unable to get Fox plushness, something about foxes oil system? But my lyric and zeb are close to the fox. I might be dreaming but I think the Rockshox have less chattering on fast 2-4 inch rocky flat trail, the foxes feel like they vibrate over the tops of the rocks, might be packing up. It takes lots of experimenting, I have not found Rockshox easier to set up as I've read others claim. Would like to ride that new buttercup, oh yeah!

warm regard Ruti

 

[STK]

Swapped out my 180 mm Lyrik for a “new” but 2021 MY Zeb over Labor Day Sale. Love/Hate relationship so far. Tracks so much better through ruts and everything BUT even at much lower psi that recommend I have migraine and arm and wrist pain after every ride.
Lowered PSI from 60 to 50 to 40 then added 1, 2 then 3 tokens to not bottom out. Somewhat better.
Gen 1 Kenevo has 180mm Ohlins coil with 30% sag, so even at 40 psi Zeb was only at 15% sag and the bike feels very unbalanced. So….
Installed a new 190mm Airspring with Buttercup and running 38 psi, 3 tokens and the new airspring seems to add a metallic 4th. It is still very stiff but much more plush. Probably mostly just due to lower psi not the new airspring but it was just hard to wrap my head around going that low. But looking inside the positive air chamber, it is massive even with tokens and has to accommodate so many travel lengths. On my first few test rides my hands and arms are sore but severe migriane after every ride is gone. Love the 190mm so far too. Slackens it out a tad and I prefer a more upright stance. May bite me a bit on extreme steep climbs but I probably have no business trying that anyway. My rule generally is if I can roll down I can attempt to climb it.

 

[Planemo]

I tried all the setting combinations, landed here. 0 tokens 0 Compression some rebound pressure in the 60's. I am unable to get Fox plushness, something about foxes oil system?

Could be, but as has been mentioned before, the bushing clearances can be a bit of a lottery with RS and you can end up chasing your tail trying to sort stiction and harshness, spending hours and hours dicking around with pressures/tokens/damping etc when all the time it's just a poorly sized bush/s.

I stripped my 180mm Domains right down to check the bushes, each leg in turn, then both legs BUT crucially to either have the wheel installed or a makeshift axle that clamps the lowers at the same width as the hub. On my tests the uppers slid into the lowers under their own weight, which is good. If they don't, its bushing resize time. I always fit SKF green seals too, they have noticeably reduced stiction.

 

[mike156]

These long travel forks tend to add a lot of spring rate deep in the travel due to the lowers. There is very little volume at bottom out in the lowers so the more travel you have, the higher the compression ratio and the more progression. On the Lyrik, it adds 60-80 lbs of force at bottom out, which is about 20-30% of the total force. The F38 uses the volume between the inner sleeve and the stanchion to increase the volume of the lowers. (I've seen people say it increases the volume of the negative spring but that is incorrect) Pretty smart design, along with it also reducing the piston diameter making the positive spring more linear.

In my experience, if I go off of trying to bottom out the fork on the biggest hits I do, the fork is way too soft. I don't do big jumps and drops though. Setup the spring rate based on how you want the bike to balance out. Tweak progression as needed if you are bottoming out.

 

[2stroked]

I was struggling with my fork, running lower air pressure and still not bottoming out and not feeling as plush in the first part of the travel. I went on You Tube and found a video of a guy that would push his fork about 20mm into the travel before tightening the shaft bolts so it would have a bit of negative pressure in the lower legs. I did it with my 23 Ultimates before realizing I could do the same thing with the lower leg air bleeders, made a difference in the way the first part of the travel felt and was closer to the recommended air pressure settings in Trail forks. With the Debonair + you don’t go off sag settings as per the manual.

 

[Rando_12345]

Same as above, when I got the bike I was running the recommended pressure and all felt good, over time it got harsher and harsher, dropped 20 psi to still have usable travel range. (at its worse, ~50psi for a 75kg rider and still only getting 80% travel)

Then did the trick above, put your bike upside down with no air in main chamber, loosen the bolts and tap with mallet to release air from the lowers, then put a bit of weight on the axle/lowers to have 20-30% sag as you tighten the bolts back up. I'm running the recommended air pressures again and fork feels good (70psi, 75kg, can get full travel on big jumps to flat).

I have read a variant of the trick but leaving 30psi in the main chamber when you under the lower bolts, have not tried that. Will have to see how many weeks/months go by before have to do the lowers air release.

 

[2stroked]

I’m not sure how having air pressure in the main chamber would help, I think it would make it more difficult since you are trying to compress the fork with air in it and trying to push the air shaft in, I don’t really see any benefit to air being in the chamber?

 

[2stroked]

Went for a ride today and the Zeb was way better even with the recommended pressure, definitely could go lower but at least it’s closer to what I expected as far as how it felt on the slower smaller hits

 

[Planemo]

I went on You Tube and found a video of a guy that would push his fork about 20mm into the travel before tightening the shaft bolts so it would have a bit of negative pressure in the lower legs.

I understand how it would work, up until the point of first compression when the piston passes the notch and equalises the neg with whatever is in the positive, irrespective of what might have been in the negative to start with.

Quite happy to admit I'm missing something though.

 

[Bones]

I understand how it would work, up until the point of first compression when the piston passes the notch and equalises the neg with whatever is in the positive, irrespective of what might have been in the negative to start with.

Quite happy to admit I'm missing something though.

I just have to reply to this.
There is some utter crap on the internet.
The air shaft in the upper leg is completely sealed off from the lower leg providing the lower air seal is working on the shaft.
Adding air to the lower legs is going to be similar to adding a token and making the rebound faster. And that's probably what you need to adjust.
The air won't compress so it will push the forks back up.
It will be like having too much oil in the lower legs and possibly force it out of the stansion seals .

 

[Planemo]

Got that, and I think your reply is actually to 'YT guy' who suggested adding air to his lowers

But you do raise something - I appreciate that the airshaft is sealed from the lower, but anything in the lower will still affect the airshaft operation will it not? A bit like why F38's have pressure release buttons on the lowers.

I presume 'YT Guy' went along the lines of thinking that if he actually added pressure to the lowers then it would do 'something beneficial' to the uppers...

Not saying I would try it, or that it works, just trying to see his thought process after 2stroked mentioned it.

 

[Bones]

Sorry yes general reply to whoever thought it was a good idea!
The air shaft itself is not affected but the extra air is pushing on the bottom seal and helping to keep the fork extended. It's also forcing the forks back up whilst in use and acting as a bottom out damper. But it's doing this on the wrong side of the fork. Hence the suggestion that the rebound and token need adjusting to keep with the forks design.
Quick edit. The factory 38s rear valve is a bit of a gimmick. It's too release pressure when the bike is set up at sea level and then you go into the mountains and the air pressure is different.
I have the 38s and fox UK say that the pressure difference is very little.

 

[Planemo]

The air shaft itself is not affected but the extra air is pushing on the bottom seal and helping to keep the fork extended. It's also forcing the forks back up whilst in use and acting as a bottom out damper.

Yeah I think thats where the YT guy is trying to come from. Although adding air to the lowers won't affect the air spring chamber pressure, it does add air pressure under the stanchions. The obvious question one has to ask therefore is.....why not just add more air to the airspring to achieve the same thing...

YT guy is basically creating a dual air chamber, presumably on the premise that 2 is better than 1

The factory 38s rear valve is a bit of a gimmick.

Oh for sure. The pressure difference between even the top of Everest and sea level is only 10psi so not exactly monumental to a set of forks. I was just pointing out that any pressure in the lowers that is different to ambient will by default change how the airspring reacts. Which is what you also confirmed. How much it reacts is of course down to how much you throw in there...

 

[Dax]

YT guy needs to buy ohlins.

 

[High Rock Ruti]

I was struggling with my fork, running lower air pressure and still not bottoming out and not feeling as plush in the first part of the travel. I went on You Tube and found a video of a guy that would push his fork about 20mm into the travel before tightening the shaft bolts so it would have a bit of negative pressure in the lower legs. I did it with my 23 Ultimates before realizing I could do the same thing with the lower leg air bleeders, made a difference in the way the first part of the travel felt and was closer to the recommended air pressure settings in Trail forks. With the Debonair + you don’t go off sag settings as per the manual.

High Rock Ruti

Please specify "shaft bolts" , this sounds really interesting, in light of the post about about bushings creating "stiction"?

Warm Regards Ruti

 

[2stroked]

High Rock Ruti

Please specify "shaft bolts" , this sounds really interesting, in light of the post about about bushings creating "stiction"?

Warm Regards Ruti

The bolts that attach the air shaft and damper shaft to the lower legs. You could also just use a tie strap between the seals and stanchions.