New RockShox ZEB: What Downhill World Cup technology does to an Enduro fork!

Conclusion from Max Fuchs, BIKE test editor

The new features on the ZEB are having an effect - a successful relaunch! Especially on high-speed sections, the ZEB literally eats up rough hits, releases its travel generously but in a controlled manner and smooths out even nasty rock gardens or root carpets - just as a high-end enduro fork should. In our estimation, the new ZEB even comes close to the Fox Podium, which currently sets the benchmark in the enduro segment. In terms of traction and directional stability in corners or off-camber sections, however, the Podium is still the benchmark due to its design and significantly lower torsional stiffness. In general, however, one can say: traction, comfort, absorption capacity - the ZEB has improved in all of these areas without sacrificing control or feedback.

Four years, a completely new product

With the new ZEB, RockShox ends the longest fork production cycle in its history - and doesn't do things by halves. Exactly one component remains from its predecessor: the thru-axle. Casting, fork crown, stanchions, air spring, damping - all new. The tried and tested 38 mm stanchions provide the necessary stiffness for enduro use. The suspension travel ranges from 150 to 180 millimetres, available in 27.5 and 29 inch. Prices start at 1080 euros for the Select version, while the Ultimate model is available for 1415 euros. The Select+ versions are not available from retailers for the time being.

Technical data: RockShox ZEB MY27

Predictable: The Linear XL air spring

The technical centrepiece of the new ZEB originates from the Downhill World Cup: the Linear XL air suspension unit in cartridge design was developed in close cooperation with RockShox athletes and is now available for the first time in an Enduro fork. The principle: As the name suggests, it generates a linear spring characteristic. This means that the force for compressing the spring increases constantly and evenly over the entire spring travel - the result is a constant and predictable ride feel, similar to a steel spring.

To achieve this, RockShox has reduced the ratio between the piston surface and air shaft and at the same time created more air volume in the negative chamber - both measures that benefit the most linear spring characteristic possible. The force required to overcome the breakaway torque of the fork is very low due to the large negative chamber, and the spring can work extremely sensitively at the beginning of the spring travel. In the middle, it offers a lot of support, and towards the end, a mechanical anti-puncture device protects against bottoming out.

AirAnnex: The bump with function

The distinctive bump at the lower end of the air spring side is not a design element, but the so-called AirAnnex - an additional air chamber that increases the volume in the left immersion tube. The reason for this is that the damping unit in the right-hand dip tube is more compact than the new air spring cartridge. Without equalisation, both sides would work with different air volumes, which would lead to uneven progression during compression. This is exactly what the AirAnnex prevents.

Breather Holes: Two small holes, big effect

RockShox has provided each stanchion tube with two holes below the oil seals - the so-called Breather Holes. They enable faster and more even air circulation in the casting during compression. The aim here is also to prevent uncontrolled progression peaks and to ensure a characteristic curve that is as linear and predictable as possible.

Volume spacers remain possible

If you prefer a more progressive characteristic curve, you can still install volume spacers. AirAnnex and Breather Holes are only intended to prevent unwanted progression - targeted adjustment of the characteristic curve via the air volume is still possible.

ABO: When the suspension travel is fully utilised

The more linear characteristic curve comes with a catch: because the maximum suspension travel can be utilised more easily, the fork can also bottom out more easily in extreme cases than forks with a more progressive characteristic curve. This is precisely why RockShox has developed the ABO (Adjustable Bottom Out) - a bump stop that can be adjusted using an Allen key. It engages on the last 7 to 17 millimetres of the spring travel and also absorbs hard impacts. This eliminates the typical metallic bang when bottoming out.

ButterWagon: Constant slide bush lubrication

Less friction is the second major development focus of the new ZEB. The ButterWagon technology solves the problem with an approach that is as simple as it is elegant: a network of milled recesses on the stanchions, below the oil seals. The structure of the recesses is reminiscent of the surface of a golf ball - only with greater spacing. With every spring movement, they absorb oil and release it again via the sliding bushes. The continuous lubrication reduces friction losses, enables a finer response and pays dividends in terms of durability. The system is flanked by more viscous Maxima 920 W15 oil, new grease and revised wipers - all measures that further reduce friction in the chassis.

Charger 3.2: More damping because less friction

Less friction only sounds like an advantage at first - but it has a direct consequence for damping. This is because friction acts like additional, natural damping during compression. As RockShox has declared war on friction losses in its new forks, the tune of the new Charger 3.2 unit is significantly firmer than the Charger 3.1 damping cartridge in the previous model. This compensates for the lack of natural damping and prevents the fork from rushing uncontrollably through its travel.

The range of functions remains familiar: rebound and separate high and low-speed compression stages, all manually adjustable. What is new is the numbering of the compression adjusters. The basic setting starts at 0, from where the damping can be gradually increased (+) or reduced (-).

ButterCups: the vibration filters

Not everything is new. In addition to the thru axle, the ButterCups have also remained. The elastomers at the lower end of the air spring and damping unit are already familiar from the old generation of forks. They support both units floating in the chassis and, according to RockShox, reduce high-frequency vibrations by up to 20 per cent. The result: less strain on hands and forearms, less fatigue on long descents, less arm pump.

New casting: speed ports and mudguard mount

In addition to the AirAnnex, two other details stand out on the new casting. Firstly, the so-called speed ports - struts on the front of the triple clamp where it joins the fork tubes. Although they do not directly make the ZEB a faster fork, they do take tension out of the bush seats under load and thus reduce friction even further. Secondly, the plastic cover in the centre of the triple clamp conceals mounting points for RockShox's own mini mudguards - seamlessly integrated without restricting maximum tyre clearance.