Ross reviews the 38mm RockShox Zeb Ultimate, a big and burly enduro fork made to bridge the gap between the Lyrik and Boxxer.
Today sees RockShox launch a brand new fork – the Zeb – named after Zebulon Pike, the intrepid explorer who first attempted to summit Pikes Peak in the Rocky Mountains back in 1806. With an aggressive design and chunky 38mm stanchions, the Zeb is designed as a hard-hitting enduro fork that bridges the gap between the Lyrik and the Boxxer.
Based in Colorado Springs, RockShox’ design HQ sits under the shadow of the 14,115 foot Pikes Peak mountain and the Zeb is definitely a product of its environment. Designed to handle everything on the near 8,000-foot singletrack descent of Pikes Peak, the Zeb is aimed at enduro racers wanting to take on the world’s toughest enduro courses.
With four models in the range – Zeb, Zeb Select, Zeb Select+ and Zeb Ultimate – and available in 170mm – 190mm options, the Zeb is designed for the modern crop of long travel enduro bikes. We’ve been lucky enough to have a 29in 170mm Zeb Ultimate in Signature Slab Grey on test for the last month or so, to really put it through its paces and see how it stacks up on the trail.
Taking pro rider feedback into account when designing the new fork, one of the biggest gains of the new chassis is a claimed 21.5% increase in torsional stiffness over a comparable Lyrik fork. The engineers at RockShox put a lot of time and effort into creating the best stiffness to weight ratio possible, which in turn increases overall performance. By increasing the torsional stiffness, it allows the fork to hold a better line through rough sections and rocky tracks, allowing riders to brake less, ride faster, and remain less fatigued.
On top of the torsional stiffness gains, the Zeb is also claimed to be 7% stiffer in side bending and 2% stiffer in fore aft bending. This is thanks to not only the increased size in the stanchions but also the brand new lowers and crown.
The new aluminium crown features a more angular look than previous forks due to excess material being machined away in strategic places to give it the strength to weight ratio that RockShox was looking for. The new Zeb is only available in one offset per wheel size with RockShox settling on 44mm for the 29in and 38mm for the 27.5in.
Bonded into that crown are chunky looking ano black 38mm lowers and inside the right-hand leg is a Charger 2.1 RC2 damper. While the performance and characteristics of the damper are the same as that found in the Lyrik, the architecture has been completely redesigned to fit the bigger diameter 38mm stanchions.
As with other Ultimate level forks in the range, on the top of the right stanchion is a high-speed compression adjuster offering up five different settings. Go left for less, right for more. On top of that dial is the low-speed compression adjuster that has 18 clicks of usable low-speed compression. In the usual spot on the bottom of the leg, you’ll find a single rebound adjuster, rather than separate high and low that you find on other brands. RockShox’s mantra with the Zeb is ‘features that count’ rather than ‘feature count’
Look over to the left hand side and you’ll see the familiar air cap and valve. As with other RockShox forks, the Zeb also utilises the Bottomless Token system which allows for fine tuning the performance. The tokens screw into the underside of the air cap which is accessed using a standard cassette tool.
Inside that left hand stanchion you’ll find the Debonair Air Spring. While the Debonair for the Lyrik and the Pike was recently updated, the Zeb’s Debonair spring has been re-designed specifically for this fork including more negative volume. The new spring is designed to be super supple in the initial part of the travel, but also keep things riding high for added support and confidence on steep and demanding tracks.
Dropping down to the lowers, the new arch has been purposefully moved out to give better clearance for chunkier headtubes and the new integrated fender. That new fender mounts to the back of the arch via three mounting points to do away with zip ties and keep things looking clean. Internally, the Zeb’s new chassis has been designed to maximise bushing overlap to reduce friction and keep things running smoothly. To further reduce that friction, the Zeb uses long-lasting SKF wiper seals to keep stiction to a minimum, and grit and dirt out.
The heavy hitting intentions of the Zeb carry through to the direct brake mount which is sized for a big 200mm rotor, although this can be further increased to 220mm with the correct post mount kit. It’s also possible to run 203mm rotors with the correct adapter. Keeping everything nice and secure is a 15mm through axle and the Zeb is also compatible with Torque caps for those looking for added stiffness.
Setting up the RockShox Zeb Ulitmate
As with all RockShox forks, set up was nice and easy on the Zeb. With a handy pressure guide stuck onto the lowers it’s easy to get air pressures and sag set somewhere near by following the guide then tweak to suit.
With the Zeb sporting 38mm stanchions, the increase in internal volume translates to less pressure in the forks for the relevant weight. For example, on a Lyrik Ultimate 160mm, I usually run around 85psi for my weight of 85kg. With the Zeb, this was reduced to just under 70psi to get my preferred sag of just over 20%.
With the damper having the same characteristics as the one in the Lyrik Ultimate (a fork that I’ve spent quite a bit of time on), and after chatting with the guys from RockShox during set up, I started with the high speed compression fully open and the low speed a couple of clicks on from fully open. Since then those settings have remained pretty much unchanged.
- RockShox Zeb Ultimate Slab Grey 29”
- Air Spring: Debonair
- Wheel size: 29″
- Travel: 170mm
- Damper: Charger 2.1 RC2
- Offset: 44mm
- Upper tube: 38mm aluminum
- Weight: 2281g (29” / 170mm / Maxle Stealth / Uncut Steerer)
- Price: £969
On the Trail:
Back at the end of May the Zeb was fitted to the front of a Santa Cruz Megatower, a bike with a similar intended use. Since then it’s been ridden on every type of trail I’ve been able to get it on. From big, rocky, and natural, to flowy hero dirt turns, to steep tech, and everything in between.
As a fork that’s designed for world level enduro racers it’s going to have to climb as well as descend and the Zeb does a good job of that. There’s minimal bob under pedalling and the short offset helps get round tight turns without fuss. The SKF seals and redesigned air spring do a great job of keeping things active, letting the fork track the ground and soak up small bumps.
Once you get gravity on your side and speeds pick up though the Zeb really comes into its own. Getting up to speed you can really work the front end of the bike on fast flowy trails, using the mid-stroke support to pump downslopes gaining momentum. The impressive small bump sensitivity does a good job of cutting out small trail chatter while still remaining supportive for popping up and over trial obstacles and gaps.
On big, chunky, rocky trails the Zeb stays super composed, with the added torsional stiffness really letting you pick a line through the roughest of rock gardens. Just get off the brakes and let the bike run and the Zeb does a great job of staying on track and soaking things up. The same can be said about big impacts, with the Zeb just taking them in its stride. I’ve not used full travel that often on the Zeb despite some pretty big drops and shady landings, but when I have, it’s stayed nice and composed with no harsh bottom out or buckaroo moments.
The small bump sensitivity and good tracking help it keep a line over off camber and rooty trails letting you concentrate on riding and looking up rather worrying about losing your front wheel. And the same can be said about fast turns. Turn it in, get off the brakes and the fork does a great job of gripping and supporting through the whole turn without diving. The short offset enhances this and there’s a directness to the steering which lets you really push the front end in and trust it’ll grip.
When things get really steep the Zeb does a great job of staying high in travel, without blowing through, adding confidence and keeping plenty in reserve for when needed. This also translates to plenty of support for when you’re really leaning on the front, whether that’s on slow speed super tech, hopping the bike around, or on mega steep fast turns, the support is there to push on with plenty in reserve.
During the test period I’ve mainly had the high speed compression fully open. On one particular trip where the trails were faster and flowier I did increase the HSC a click for added support, but for my general mix of steep and rough riding I’ve found that running it fully open and just a couple of clicks of LSC has given me the perfect mix of small bump sensitivity, straighten line tracking and big hit support.
RockShox Zeb Ultimate | Overall
The Zeb has been designed and built to be RockShox’s ultimate big hitting single crown enduro fork and take on the worlds toughest enduro tracks and it doesn’t disappoint. I’ve been lucky enough to ride a lot of the recent top end forks and the Zeb is up there with the best.
On the trail it feels stiff and precise without being harsh and never feels out if it’s depth, no matter what you point it down. It’s simple to set up, has a range of usable adjustments and inspires confidence letting you get on with riding. Is the new Zeb Ultimate the ultimate long travel enduro fork… quite possibly.
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|Tested:||by Ross for 1 month|