Luftkappe for Zeb

D(C) · Oct 30, 2021

Vorsprung recently released a Luftkappe for the Zeb. I got mine yesterday and did the install. The orange piston head on the stock air spring unthreads and is replaced by the Luftkappe assembly. I was able to use the foot nut to hold the air spring while unthreading the upper piston - I didn’t need shaft clamps.

The photos below show the stock and Vorsprung air springs side by side. They are positioned so both are at top-out (the stock one is a 160 spring, and the Luftkappe is 170).

You can see that the upper seal has been moved down a few mm, which will cause it to pass the air transfer dimple a little bit into the fork’s travel and pressurizes the negative spring at a higher pressure. The stock spring equalizes at top-out.

the Luftkappe also adds the dome above the upper piston and removes the big orange top-out bumper assembly (no longer needed since it tops out pneumatically). Both of these changes increase negative spring volume.

I’ll report back after I ride it, but so far, I have it set up with 65 psi and 0 tokens, and weigh 170 lbs. My preferred setup pre-Luftkappe was 57.5 psi and 2 tokens for 160 and 55 psi and 1 token at 170.

The fork tops out fully to 170 if I pull the bars off the ground after compressing the fork, but stops topped out at about 165 mm if I don’t. The pneumatic top-out means zero preload at top-out, so even a small amount of friction could prevent the fork from continuing to extend.

Jesse Hill · Oct 31, 2021

It’ll be interesting to see how it rides compared to the 2022 Zeb air spring that looks like Sram put their own luftkappe on.

mtnbkrmike · Oct 31, 2021

This is my second season running a Luftkappe on my 36. I will be interested to hear whether your observations with your Zeb are similar to mine with my 36.

Jukka4130 · Oct 31, 2021

Vorsprung has a strong track record of bringing products to the market that deliver what it says on the label. It's hard to think that this one would be different. Interested to hear some first impressions, though!

Jesse Hill · Nov 1, 2021

I’m sure it’s an improvement and as the saying goes imitation is the strongest form of flattery and if you look at the 2022 Zeb spring you’ll see it’s a domed piston like a luftkappe.

D(C) · Nov 1, 2021

I got a couple rides in over the weekend, but not enough time yet to say that I've fully put things through the test. So far, it feels like an improvement over the stock air spring. I had to speed up the rebound a couple clicks, as it tops out with less force, but my starting air pressure feels pretty close to where I want it.

The stock air spring sits very high in its travel, which made setup a bit challenging. I tried both 160 and 170 air springs and preferred the 160 since the 170 felt too tall. Even then, to get a ride height that didn't result in the feeling of skipping off the trail, I ended up with a mid-stroke that felt a bit mushy. The Luftkappe sags more, which helps the bike feel more settled, but then there is substantially more support deeper in the travel. The 170 air spring now feels good.

I need to put more miles in, but Luftkappe seems like an improvement when it comes to faster riding where support is needed, and also on steeper terrain where the stock air spring would dive. I will say that the stock air spring was maybe more forgiving at low speeds due to the softer mid-stroke, and also maybe felt a bit more lively due to the higher spring rate early in the travel.

mtnbkrmike · Nov 2, 2021

Interesting. Apart from the lower sag comment, my observations with my 36 seem to be a bit different. I’m no suspension guru by any stretch though (understatement of the year), so take my comments with a HUGE grain of salt. It may also be that the Luftkappe reacts differently with the 36.

I wasn’t happy at first with the dropped front end. I thought I had made a mistake installing it. I increased my PSI a bit though, and things instantly improved.

I kinda forget what it was like without it though, so maybe I’m way off.

Gman086 · Nov 2, 2021

Since i've owned my Zeb I've been hoping for the Luftkappe because it doesn't suffer from lower leg pressure ramp up like the smaller diameter forks do (and thus the need for a Secus)... the Zeb has decent damping but somewhat poor mid-stroke support and a bit harsh off the top when you air it up enough to overcome the mid-stroke issue. The Luftkappe solves all that. As the OP states, it pulls the static fork level down by about 5mm (which is actually a good thing for trail riding if you've over-forked your bike like I did) yet the dynamic ride height is HIGHER in the steeps because of the added mid-stroke support - a WIN-WIN in my book. Before my Zeb was notchy off the top but now it is butter smooth and tracks much better at any angle. It's exactly what the Zeb needed. Mtnbkermike - I have a 36 with a Luftkappe too and they feel real similar. Also note that the Zeb version is LARGER than all other Luftkappes and takes the volume of TWO volume spacers (which is where I needed to be on a 170mm Zeb). I ended up using the same air pressure (73 psi) which seems spot on and Vorsprung also recommends starting at the same pressure for the Zeb because of all the volume the larger piston takes up. I'm not associated with Vorsprung in any way but I can say that any aggressive riders with a Zeb should get this, without a doubt, as I'm certain they will sell out soon!

Have FUN!

G MAN

D(C) · Nov 2, 2021

Gman086 said:
I ended up using the same air pressure (73 psi) which seems spot on and Vorsprung also recommends starting at the same pressure for the Zeb because of all the volume the larger piston takes up.

I'm thinking whether you run the same or more pressure with the Luftkappe compared to the stock spring depends on your approach to the stock spring setup.

At 170 lbs, 65 psi (my Luftkappe pressure) felt about right for mid-stroke support with the stock air spring, but I couldn't deal with the lack of sag, so I settled on a setup that lacked mid-stroke support but gave me a better feeling off the top. 73 psi in a 170 Zeb definitely sounds like a setup that prioritizes mid-stroke support, so that is probably why keeping the same pressure with the Luftkappe worked for you. If I ran the Luftkappe at 55 psi, that wouldn't go well...

minimusprime · Nov 3, 2021

This is pretty rad, not going to lie. I put a secus on my zeb because I couldn't quite get along with the pre-loaded air spring feeling and the rather empty mid stroke. With the stock air spring, I ran a 160mm because the dynamic/static ride height was so high, but with the secus I went to a 170mm air spring and ran a bit more sag. Overall, it transformed the fork and made it better then what I experienced out of the 38 factory with regards to spring support.

While I love the secus, it's expensive, and complicates a few things like flying with the bike and makes the lower leg service ever so slightly more involved. If the luftkappe can get 80% of the way there without the expense/complication, that would make it an awesome option.

I wish I could try both options back to back and give my impressions. I'd have two concerns that the luftkappe wouldn't make the zeb as good as the secus does. 1) the ramp up from the air trapped in the lowers. I feel like this starts to be a significant issue with longer travel versions of the zeb, 170+ where not as much at 160mm. 2) The luftkappe is going to make the fork more progressive as it's reducing the positive chamber and essentially adds a token.

I'm not the heaviest rider, but I'm 180lbs and can ride well enough. The Zeb is quite progressive from an air spring prospective even with zero tokens. I feel like there's a chance that with a 170mm plus zeb, and a luftkappe, I may not be able to use full travel.

D(C) · Nov 8, 2021

I have a couple more rides on the new setup and everything I said previously holds. I wasn’t that stoked on the Zeb’s air spring before but now I am. It sits comfortably into its travel off the top but then feels substantially more supportive in the mid-stroke, with a proper gradual ramp-up. I guess the only potential negative is that the fork feels less poppy than with the stock spring - I was previously pushing against the very top of the stroke when pumping, whereas now that resistance comes more gradually and deeper in the travel. But the fork feels far more composed, and I find I am able to relax more while descending as a result.

I’m 170 lbs on a medium 2021 Norco Sight 29. My Luftkappe setup is 170 mm travel, 65 psi, 0 tokens, 0 or 1 click HSC from open, LSC fairly open. I’m regularly using 160 mm of the 170 mm travel on proper descents, with full bottom-out achieved on big hits.

I’m running 40 mm rise Renthal bars and Renthal stem (6 deg rise), with 10 mm headset spacers and a low headset dust cap. This is the same cockpit setup I was running with the 160 mm stock spring. I find cockpit settings and suspension ride height go hand-in-hand.

cscsw · Apr 11, 2022

Why you keep the top out bumper?

D(C) · Jul 3, 2022

Now that the new Zeb air spring is out in the wild, I’d be interested in any details on how it compares to the previous air spring with Luftkappe.

jetrick07 · Jul 5, 2022

Also interested on this one, I have a 2022 Zeb. Im thinking of buying a Luftkappe before upgrading the internals to the new Debonair+ and Charger 3.0. If the performance gain is marginal I will stick with the Luftkappe.

boellefisk · Jul 5, 2022

Can't compare it to luftkappe but on a 180mm fork I find the new spring too progressive.
I spent a week in the alps on it, roughly 4.5km vertical depending per day. Couldn't get it properly dialed.
I suspect the luftkappe would have the same problem.

D(C) · Jul 5, 2022

boellefisk said:
Can't compare it to luftkappe but on a 180mm fork I find the new spring too progressive.
I spent a week in the alps on it, roughly 4.5km vertical depending per day. Couldn't get it properly dialed.
I suspect the luftkappe would have the same problem.

You are probably correct. Even with the fork at 160, I am only seldom using every last mm of travel with the Luftkappe installed. Still, the feel is a big improvement over the stock 2020-2022 spring.

One question I have about the 2023 air spring - does it need to be cycled through its travel to equalize positive and negative pressures, or does it equalize at topout like the previous air spring?

PHeller · Jul 5, 2022

Put your money towards a Secus and call it a day.

D(C) · Jul 5, 2022

The graphs in this thread are insightful. My take is that, if you can live with the end of stroke ramp, the Luftkappe offers good performance in a cheaper and more integrated package than the Secus.

Fox 36 Stock vs Luftkappe vs Secus

Shockwave95 · Jul 13, 2022

I just bought a Zeb ultimate 170. I right away got install a Luftkappe in it. I am at about 20% sag. All I can get is 130mm of travel so far. Is this normal? I would like to get about 150mm and keep a 10mm for those moment that I really need it.

D(C) · Jul 13, 2022

What are your settings? The Luftkappe is approximately equal to two positive tokens, so it will add bottom-out resistance, and you'll want to remove 2 tokens as a starting point. If you were already running fewer than two tokens, there is no way to get around the extra ramp.

I had air trapped in my lowers at one point, which made it difficult to use full travel.

Shockwave95 · Jul 13, 2022

I have 0 token in the fork. High speed compression fully open. Low speed compression 6 clicks in from full open.

Shockwave95 · Jul 13, 2022

I weigh 225lbs I was at 85. I drop it at about 81 for my next ride.

ehfour · Aug 17, 2022

Curious if you figured it out?

Also what's your local riding spot

MtnBkrBob · Jul 29, 2022

Glad I found this thread. I'm in the process of upgrading my '21 ZEB Select +.

Good info in here.

D(C) · Aug 4, 2022

One thing that occurred to me when I did a service last night - you'll want to release the air from the lowers after equalizing positive and negative chambers after doing the install. The final height of the air spring top-out isn't set until the spring is equalized, so if you mount the lowers before equalizing, the lower leg volume at top-out will change and could end up pressurized.

I stuck a zip tie down the dust wiper after equalizing and heard a hiss from both legs.

wurst656 · Aug 14, 2022

Hey Guys,

i'm thinking about trying the Luftkappe in my Zeb. I'm quite happy with my Zeb's performance but i'm curious about the effects of Luftkappe since i put a megneg on my super deluxe. The bigger negative spring really improved my shocks performance and i'm wondering if the Luftkappe might do a similar thing for my fork.
I'm about 78kg fully kitted and currently run 58psi in my Zeb with 3 tokens installed. HSC is in the middle, LSC 7 klicks from open. Rebound is 8 klicks from open.
I'm not after a more supple fork but i find the Zeb's midstroke support somewhat lacking in certain situations.

D(C) · Aug 14, 2022

wurst656 said:
Hey Guys,

i'm thinking about trying the Luftkappe in my Zeb. I'm quite happy with my Zeb's performance but i'm curious about the effects of Luftkappe since i put a megneg on my super deluxe. The bigger negative spring really improved my shocks performance and i'm wondering if the Luftkappe might do a similar thing for my fork.
I'm about 78kg fully kitted and currently run 58psi in my Zeb with 3 tokens installed. HSC is in the middle, LSC 7 klicks from open. Rebound is 8 klicks from open.
I'm not after a more supple fork but i find the Zeb's midstroke support somewhat lacking in certain situations.

Yeah, the Luftkappe will let you run higher pressure for more support without the fork becoming to firm off the top/low on sag.

wurst656 · Aug 14, 2022

you mentioned having to adjust your rebound with the luftkappe? I like to run a rather stiff and fast setup, but have slowed down my rebound from 6 to 8 klicks from open. what adjustments did you make to rebound and compression damping after installing the luftkappe?

As i did with the megneg, i also want to remain around the same amount of sag i run.
Removing two tokens and running similar sag should provide better mid stroke support and slightly better inital response?

D(C) · Aug 19, 2022

wurst656 said:
you mentioned having to adjust your rebound with the luftkappe? I like to run a rather stiff and fast setup, but have slowed down my rebound from 6 to 8 klicks from open. what adjustments did you make to rebound and compression damping after installing the luftkappe?

As i did with the megneg, i also want to remain around the same amount of sag i run.
Removing two tokens and running similar sag should provide better mid stroke support and slightly better inital response?

It’s been a few months since I installed the Luftkappe on the Zeb and I’ve fiddled with rebound often depending on how things feel. I don’t remember where I landed compared to before the install.

But I did recently install a Luftkappe in the 2021 Fox 36 on my hardtail and I had to open up LSR a few clicks to make it feel good. The softer initial spring rate results in less rebound force near the top of the travel, and I found the fork was packing up a bit into the mid-stroke.

wurst656 · Aug 27, 2022

I damaged the shaft of the air spring trying to install the Luftkappe without shaftclamps. very stupid. i wasn't able to get a new 170 spring so i ended up ordering a 180mm air spring which i feel lucky to even get my hands on.
i'll hopefully get to try the Luftkappe next week after the new airspring arrives...

D(C) · Aug 27, 2022

wurst656 said:
I damaged the shaft of the air spring trying to install the Luftkappe without shaftclamps. very stupid. i wasn't able to get a new 170 spring so i ended up ordering a 180mm air spring which i feel lucky to even get my hands on.
i'll hopefully get to try the Luftkappe next week after the new airspring arrives...

That sucks that you wrecked your air shaft.

I’ve found that I can do the install without shaft clamps by holding the flats on the foot nut of the air shaft with an adjustable wrench, then unthreading the stock orange piston head with another adjustable wrench.

wurst656 · Aug 28, 2022

Tried that initially, didnt work. The foot nut always came loose before the piston did. i've ordered some clamps but i'll just secure the foot nut with some loctite if the new shaft arrives before the clamps do. hopefully that'll do it.
the dent isnt even visible and you can barely feel it. but it's enough to get a little stuck when it passes the seal..

I was happy to read that you increased your travel by 10mm when you switched to the Luftkappe. i love my bike's handling and i'm slightly concerned that the new 180mm spring will negatively affect my bikes handling, even though it's just a 10mm increase.

wurst656 · Sep 1, 2022

I've just installed it. Switched from 170 to 180mm due to part shortage and also had to release some air from the lowers. I'll update this once i get back from my test ride.

so update: did a few different trails, multiple runs. i tried different pressures from 60 to 62 psi and also added and removed compression damping from my setting pre luftkappe.
since i also increased travel from 170 to 180mm you can't really compare pressures, in my opinion. i ran my 170mm zeb with 58 or 59psi, which equated to a little above 15% sag. i weigh 80kg fully kitted. with the luftkappe, i currently run 63psi, which results in about 20% sag on the 180mm air spring. i previously ran 3 tokens and have removed all of them. compression and rebound damping has stayed the same. i don't feel like it's transformed the fork, but it noticeably improves where i previously found the fork lacking. yes it does feel a bit more supple, but mainly it doesn't blow through the midstroke as easily and thus feels a lot better on steep stuff and through bigger compressions. at actually feels pretty dialed already.

MtnBkrBob · Sep 9, 2022

Got a couple rides on my newly installed Lufftkappe on my '21 ZEB select + (Trek Rail XT). Noticeable improvement, but still not satisfied. Data points: Pocahantas state park (Richmond VA). 62 years old. 200 lbs. 80 psi. 4 LSC. No tokens. 7 rebound.

Used 98% of suspension. Fork sweet spot seems to be hitting things at 15-20 mph. Seems counter intuitive, but more air and more LSC seems to soften blows. And more air & LSC helped stabilize the bike to launch over small/medium jumps.

Dougal · Nov 4, 2022

Here's how the 2021 Zeb stock air spring graphs out. It's pretty firm off the top:

ehfour · Nov 4, 2022

Dougal said:
Here's how the 2021 Zeb stock air spring graphs out. It's pretty firm off the top:

Thanks for posting this and showing what we all feel out on the trail

Is this with the updated silver seal head?
Any chance you have a similar view of Zeb with Luftkappe or Secus?
Any idea what's causing the small spike->dip mid-stroke on the Force v Displacement graph?

MtnBkrBob · Nov 8, 2022

Update on my ’21 ZEB Select + on my Rail 9.8 XT…

Have another 10 or so rides on my Luftkappe and have adjusted settings continually. Still not satisfied.

62 year old, 200 lbs intermediate – Last ride in tight deep-woods single track (east coast VA USA), was 75 psi (24% sag), 1 token, LSC 0, rebound 3 from full open. Used 80% travel. Harsh ride, especially on consecutive bumps.

Will try 70 psi next ride.

Previous ride was 70 psi (24% sag), 0 token, LSC 0, rebound 4 from full open. Used 100% travel. Decent ride.

Considering a smashpot or completely new fork & shock but may just sell the entire bike. Bikes crushes manmade bike parks, but not so good on natural single track.

Jayem · Nov 9, 2022

MtnBkrBob said:
Update on my ’21 ZEB Select + on my Rail 9.8 XT…

Have another 10 or so rides on my Luftkappe and have adjusted settings continually. Still not satisfied.

62 year old, 200 lbs intermediate – Last ride in tight deep-woods single track (east coast VA USA), was 75 psi (24% sag), 1 token, LSC 0, rebound 3 from full open. Used 80% travel. Harsh ride, especially on consecutive bumps.

Will try 70 psi next ride.

Previous ride was 70 psi (24% sag), 0 token, LSC 0, rebound 4 from full open. Used 100% travel. Decent ride.

Considering a smashpot or completely new fork & shock but may just sell the entire bike. Bikes crushes manmade bike parks, but not so good on natural single track.

Fixing the spring won't fix a crappy damper tune.

There are mods, Diaz mid-valve spring and rebound tune. DIY compression and rebound stack tuning. Push HC97 and more, from simple shim mods to complete cartridge swaps. Many are outside of the US though.

Yeah, in a perfect world suspension companies know how to tune forks properly. But we don't live in a perfect world. Custom tuning can get you pretty close to perfect.

947656 · Nov 9, 2022

To highlight how sag is a useless measurement, as it's impossible to measure accurately, you've just shown that both 70 and 75psi gives you 24% sag....

MtnBkrBob · Nov 9, 2022

Good catch. That was a typo. I don't remember what the sag was at 70 psi but failed to edit it out when I cut & pasted the other sentence. I believe it was closer to 30%. But like you said, it's hard to get consistent sag readings.

Luftkappe for Zeb

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