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Discussion Starter · #1 ·
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.

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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!
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.
 

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Discussion Starter · #6 ·
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.
 

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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.
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.
 

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Discussion Starter · #8 · (Edited)
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.
Yeah, the Luftkappe allows a higher pressure to be run without feeling harsh off the top, which results in a more supportive mid-stroke. With the Zeb, I was also looking for more sag at an appropriately supportive mid-stroke, so the extra sag is welcome. I also went from 160 with the stock spring to 170 with the Luftkappe, so I get some extra height there.

Also, re-reading my post, using the words “starting air pressure” may have caused confusion. I meant my first guess at pressure with the Luftkappe. I was running 57.5 psi at 160 or 55 psi at 170 with the stock spring, and am running 65 psi at 170 with the Luftkappe. The Luftkappe definitely feels good with more air pressure than the stock spring.
 

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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
 
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Discussion Starter · #10 · (Edited)
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...
 

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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.
 

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Discussion Starter · #12 ·
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.
 

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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.
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.
 

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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.
 

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Discussion Starter · #17 ·
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?
 

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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?
I don't know. I think it's very close to the top like c1, but every time I air up from empty I cycle through the travel each 20 psi out of habit.
 
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