RockShox Zeb Ultimate fork review

The RockShox Zeb Ultimate is designed to tackle everything this side of a DH race. We’ve been hammering several sets hard at home and in the Alps to see how it handles flat-out attack. It isn’t the biggest single crown fork RockShox has ever made (the 40mm legged turn of the century Totem gets that honor), but with 38mm legs and up to 190mm of travel, it’s ready to front up the fastest Enduro bikes. The Zeb Ultimate is the top of a four model range and once it’s loosened up from a sticky start it’s a superb flat-out gravity race or rave fork for riders who need it. Accurate setup guides, slightly lower weight and much lower price are significant wins over the Fox 38 too, but does it take the top spot as the best mountain bike fork?                                                                                                                                                                                                                                                                  

Construction 

Structurally the Zeb is an all-new fork with 38mm stanchion tubes in an oversized, buttressed crown that also allows for 1.8in steerer tube options. The thick wall steerer tube isn’t ovalized like the Fox 38 though. The brace also looks more like a bigger version of the squared SID arch than RockShox trail forks, with a lot of forward throw to increase twist stiffness by over 20 per cent according to RockShox. The big flanged dropouts use a bolted 15mm with TorqueCap cut-outs to increase contact with compatible large face hubs. 

Inside there’s a wholly new version of the RockShox DebonAir spring that uses the full leg diameter for maximum volume and a much lower operating pressure than most forks. It also balances negative and positive chambers at the stroke top so there’s no need to compress the fork to equalize. The Charger 2.1 damper cartridge is essentially the same as the one in the slimmer Lyrik, just with a resized top cap to fit the fatter legs.

Image 1 of 3

Low-speed rebound (19 clicks) is adjustable via a self-explanatory tortoise or ‘jackalope’ graphic on the bottom of the right leg while low (19 clicks again) and high speed (four clicks) compression are dial adjusted at the top. A ‘rider weight = air pressure’ set up guide sticker is stuck on the left leg and percentage sag lines are printed on the stanchions themselves for both travel options on each fork and depending on wheel size that covers from 150 to 190mm. That overlaps with the 140 to 180mm travel, 35mm leg Lyrik which weighs just over 200g lighter in comparable formats. You can also get the Zeb in 38 and 44mm offset options in 27.5-inch and 44 or 51mm in 29er. RockShox also has a Trailhead app where you can type in your serial number for pressure and damping settings for rider weight as well as spares and servicing information for your fork.

• Best enduro mountain bike
• Best budget mountain bike forks

Performance 

Between the Trailhead app and the physical guides, you’re likely to be very near the setup sweet spot without a bunch of trial and error first, which is a definite win over Fox. You might not think that’s the case at first though as it takes a good few hours for the initial friction from bigger seals and spring piston to bed in and start moving smoothly. The larger volume and lower spring pressure also mean each PSI makes more difference too, so always use an accurate shock pump and don’t be tempted to fart out pressure trailside with a stick if you’re in a hurried hunt for initial smoothness.

The way the negative spring automatically balances with the fork unloaded - rather than partway through the stroke when positive (and therefore negative) pressure is already increased - also means it’s not as sensitive as RockShox forks from a couple of years ago. The idea behind that is to sit the fork higher in the stroke and it definitely feels like it sits more on the surface of the trail rather than melting into it at the expense of occasional over travel. The means the overall spring character is more linear compared to the 38 which starts softer and more sensitive and then ramps up more in the mid-stroke. While it’s not as pronounced as the 38, the Zeb progression is really well judged over the complete stroke and we never slammed out even when running zero volume spacers. However, you might want one or two in if you’re on a serious hucking mission or you’re in Clydesdale Class.

While it’s easy to get obsessed with trying to find and justify tiny differences between forks, the real win from the latest generation suspension is that it’s much more consistent with no horrible holes and vicious spikes lurking somewhere in the air spring and damping circuit interaction. The fantastic overall predictability of the Zeb is a prime example and once the fork got settled in and into its stride the wide-span damping adjustments make it really easy to create the level of support and sensitivity you need for your preferred style or the next trail. While our lighter (70kg) testers found they were running low-speed compression wide open to offset the stiffer chassis feel and reduced suck down, all the clicks are useful and useable. 

Presuming you’ve got the frame, tires and wheels to match, the tracking boost from the stiffer chassis can be felt easily when you’re trying to hold a straight line through belligerent rock and root sections and as long as you lift your focus and stay off the brakes the Zeb feels laser-guided towards your existing exit point. Interestingly RockShox only claims a 2 per cent fore and aft stiffness increase over the Lyrik (Fox 38 V 36 figures are much higher) but we had no issues with brake flutter or binding however hard we hauled on the 200mm rotor. While it hovers higher in the stroke when lightly loaded than older RockShox and recent Fox, Marzocchi, Cane Creek and certainly DVO forks, it still squats down to glue traction into turns and drop-aways when it needs to. As you’d hope for a hefty long travel fork it’s particularly impressive smashing into seismically significant situations whether that’s landings or blunt force trauma from big boulder slaps. While there are only 4 clicks of high-speed compression they’re all safely useable with controlled stroke braking, not a sudden wrist break feel, even in the highest resistance setting. Because they haven’t added a ton of extra fore and aft stiffness there’s less sting through to your hands when you’re running a more aggressive tune too, although it’s still definitely stout and direct in character.

While high-speed rebound is fixed we never felt successive big hits were choking or drowning the fork and there’s plenty of low-speed bandwidth to make sure it tracks and reads the trail with the character you want.

• DVO Beryl suspension fork review
• Cane Creek Helm MKII Air fork reviewed

Verdict

Once you’ve let it bed in, the Zeb is a massive and impressive fork for facing down the biggest terrain and speeds. Basic stroke feel is more linear and business-like rather than buttery compared to its obvious competitor, the Fox 38, but the on-trail truth is that if you factor in a bit of tire pressure tweaking you could set up each fork to be almost indistinguishable on the trail. At that point, the fact that the Zeb is almost 30 per cent cheaper (and often much more than that online) and the setup guides are more accurate becomes a big plus in RockShox’s favor. Just make sure that your actual riding, not just your ego really needs the Zeb rather than the lighter, more comfortable Lyrik Ultimate. 

Tech Specs: RockShox Zeb Ultimate

• Price: £969.00 / $1,366.49 / AU$1,792.99
• Weight: 2270g (170mm travel)
• Travel: 150 - 190mm travel (170mm tested)
• Colors: Slab grey, high gloss black
• Sizes: 27.5 and 29er in 1.5 and 1.8in tapered steerers