ÖHLINS RXF38M.2 AND TTX22M.2 SUSPENSION REVIEW
THE ULTIMATE HARD CHARGING COMBO?
Words by Robert Johnston | Photos by Finlay Anderson
Swedish suspension masters Öhlins have been upgrading and adding to their range steadily over the last few years, now representing the majority of categories for the gravity-minded mountain bike disciplines as well as a couple of trail and XC offerings. Looking to add their high-performance mindset to the aggressive enduro space, they released their RXF38m.2 fork a couple of years ago and updated their TTX22 coil shock to the m.2 spec. We were very interested to see how the latest and greatest Öhlins offerings performed and set about putting the 38mm stanchion fork through the ringer for a year, joined by a TTX22m.2 rear shock to match it more recently. It’s safe to say that both units are some of the best available, but they won’t be for everyone. Read on to find out why.
THE LAB | RXF38 M.2 FORK
The RXF38 m.2 is the hard hitting enduro and eMTB single crown fork in the Öhlins range, taking many of the design cues and technology from their DH38 downhill dual-crown fork. Given its aggressive intentions, the burly 38mm stanchion size was adopted from the DH38 to boost stiffness and steering precision, and due to this burly nature the RXF38 is offered only in 160mm to 180mm travel variants – this is a fork that’s designed to charge hard. There are options for a standard tapered steerer or the eBike standard 1.8” taper, all of which are eMTB approved. Available in 29” wheel size only (though 27.5” will fit, of course), the Öhlins RXF38 m.2 retails for $1,345/£1,477.
CHASSIS | As the name indicates, the Öhlins RXF38 m.2 relies on a pair of 38mm stanchions, as found on their DH38 downhill fork, and up from the 36mm stanchions of their original enduro fork the RXF36. This move was made in a bid to increase stiffness for more precise control when charging hard, however Öhlins claims to have worked on delivering a flex pattern between the crown, stanchions and lower legs that doesn’t lead to an overly harsh feeling. They also worked to shave unnecessary weight in a bid to produce a package that is still friendly enough to pedal back up the hill, tipping the scales at 2320g (160mm air spring, uncut steerer).
The wheel is secured by a 15mm, 110mm wide (aka Boost) spacing axle, which uses a floating design. This allows for any difference in tolerances between hub widths to be accepted without pulling the lowers out of alignment, minimizing friction overall. The lowers will accept up to a 29×2.6” front tire and feature a 200mm post brake mount with compatibility up to monstrous 230mm rotors. The axle to crown height for a 170mm fork is 583mm: the same as a Fox 38, and 3mm shorter than a RockShox ZEB.
DAMPER | The RXF38 m.2 fork uses the Öhlins TTX18 cartridge damper, a Twin Tube damper setup with an 18mm piston that’s also relied upon for damping in the DH38 and RXF36 forks in their range. The Twin Tube setup is nothing new to the suspension market, and simply refers to the separation of oil flow channels whether the fork is moving in compression or rebound. This offers better separation of the adjustments and reduces the chances of cavitation, which should yield more consistent damping performance. The Öhlins damper offers 15 clicks of low-speed compression which span a wide range of force, letting the same base setup cater to a wide range of rider weights and styles. High-speed compression has three settings, with the 4th position used as a climb mode with a much firmer feel. Lastly there’s a low-speed rebound adjustment. For riders with a preference outside the stock settings, Öhlins has a huge bank of different tunes which their products can be adjusted to in their service centers, to ensure you get the exact performance you desire.
AIR SPRING | The RXF38 m.2 continues to use Öhlins proven three-chamber air spring that has been used on their forks for many years at this point. This has a main positive and negative air chamber which self-equalize, as well as a ramp-up chamber that’s used to adjust progression instead of a classic air token system (the main chamber volumes can be adjusted with tokens, however). This air spring is housed in a cartridge, allowing for coil and air to be interchanged without issue and preventing the fork from requiring a full strip-down to change travel. You do however need to purchase a new air spring to change travel between the 160mm – 180mm options Öhlins offers for the RXF38 m.2, which is not inexpensive.
The ramp chamber functions differently to tokens when it comes to the end-of-stroke feel, and is infinitely tuneable to obtain the exact feel the rider desires (but with a slight increase in complexity of setup). Where a standard plastic token is a fixed item, the ramp chamber uses an Internal Floating Piston (IFP), which sits within the air shaft. The pressure of the ramp chamber is set at roughly 2 times the pressure of the main air chamber, as a rule of thumb, but can be adjusted to suit each rider. The IFP stays fully extended in the initial portion of the fork stroke, offering the smallest air volume for the main chamber. As the main air spring is compressed, the pressure inside increases, until it begins to exceed the pressure the ramp up chamber is set to. This causes the IFP to compress, and the total main chamber air volume to increase in a linear fashion as the fork is compressed further. By adjusting the ramp up chamber, the point in the fork stroke at which the IFP begins to move will change, with more ramp up pressure keeping the fork volume smaller deeper into the stroke, and therefore delivering a more progressive spring curve.
The Öhlins air spring allows the spring curve to be tuned more finely than most, to obtain the exact characteristics the rider desires. You can obtain anything from a highly supportive and fairly linear feeling with higher main air chamber pressure and lower ramp up chamber pressure; through to a soft off-the-top feeling with adequate bottom out resistance by running less main air chamber pressure and increasing ramp up chamber pressure.
THE LAB | TTX22M.2 COIL SHOCK
The TTX22m.2 is a slight update with the same main features as their well-established TTX22 coil shock. As with all coil shocks, the spring rate is modified by swapping out the coil spring, which Öhlins offers in their lightweight spring series from 251lbs/inch to 708lbs/inch, with increments of just 23lbs/inch for most of the range.
The TTX22m.2 uses Öhlins’ proven twin-tube damper arrangement, of course packaged differently for the rear shock but with the same principles of operation. They separate the rear shocks into “Trail” and “DH” versions based on their eye-to-eye length, with the Trail versions receiving a high-speed compression valve with two descending positions and a climb position, and the DH version receiving three descending positions for finer tuning. There are seven clicks of rebound and 16 clicks of low-speed compression adjustment on both versions, offering a relatively narrow tuning range compared with some.
The TTX22m.2 body is available in both standard eyelet and Trunnion mount options, and the Trunnion version is offered in a choice of “Piggyback” or “Side-By-Side” (tested) versions, letting the user select the best fitment for their frame. Regardless of the option selected, there’s a variety of different eye-to-eye lengths and shock strokes available, and shock stroke can be easily tuned with spacers which sit behind the cup that houses the bottom out bumper. This bottom out bumper has been tweaked for the “m.2” version of the TTX22, influencing a larger portion of the end of the stroke and offering a more consistent and predictable level of support to keep you from slamming abruptly into the end of your travel. Regardless of the TTX22m.2 option selected; retail prices are around the $825/£863 mark.
Öhlins has a handy “Performance Suspension Guide”: a database which covers many of the current enduro and downhill bikes on the market. It allows riders to input their model, weight and desired sag, and be provided with compatible products and baseline spring settings for each of them. This helps to take the guesswork out of the setup process, and proved to be spot-on for the rear shock on a few different bikes, but slightly less on-the-money for the fork.
RXF38 M.2 FORK
Fitting the Öhlins RXF38 m.2 to the front of the bike is not a tricky task, with the front axle offering easy and very secure fastening with a 5mm hex key due to the single pinch bolt design.
Getting the Öhlins RXF38 m.2 air fork setup can take a little more time than a Fox or RockShox unit due to the three-chamber air spring. The two positive air chambers have an interaction with each other, which can make it a little trickier to get the right balance of support in the mid stroke and support at bottom out. I found the ramp up air chamber to be surprisingly sensitive, with a 5 psi change in pressure making a notable difference in bottom out support, so it’s certainly worth paying attention to pressures in both chambers.
Once I experimented and found some numbers that worked for me though, things got very good, very fast. I found that going slightly higher in the ramp up chamber than suggested yielded the best performing fork overall for me, as at the suggested pressures there would be a tendency for a high speed “slap down” to fully blow through the travel and slam into the bottom. The chassis on the RXF38 is undeniably stout, but I didn’t feel it to be harsh. As you may expect, the fork never felt vague or susceptible to twisting in hard compressions, delivering lots of confidence to push hard, but it’s not brutally harsh and doesn’t lead to pronounced issues with front wheel deflection or hand fatigue.
The RXF38 m.2 packs a wide range of adjustment on the low-speed compression side, and notable differences in how the high-speed compression kicks in between each of the four positions, which allows you to run it fairly wide open and “free” feeling or fairly heavily damped on the base tune. For my 98kg kitted weight, I ended up between 6 and 8 clicks of low-speed compression out from closed, 3-4 clicks of rebound out, and tweaked between the two middle settings of the High-Speed Compression depending on the terrain on the menu, most of the year round. Wetter conditions where traction was in short supply, damper settings would be backed off a little to obtain a touch more compliance for improved front end grip. There’s no denying that the RXF38 m.2 is a fairly heavily damped fork as stock and riders on the lighter end of the spectrum may need to have it re-valved, but for me I was left in a happy place.
Once I found the settings that worked for me, which took a considerable effort, I was met with a real goldilocks situation where I couldn’t really ask for anything more. As comfortable as the best of them, but with mid stroke support that lets you push hard without ever flinching, and end-of-stroke performance that was never phased, the Öhlins fork offered impressive performance. This performance continued throughout the longest descents I could get to, during which the Öhlins fork maintained its composure and control regardless of how long I was pushing it. That said, I’d always welcome more compliance and comfort if there was no expense to hard charging performance, so I’ll look forward to further improvements with Öhlins flagship enduro fork in the future.
I wasn’t tracking the hours logged, but I’m certain I’m well over the service interval for the damper and there’s been no appreciable change in performance. A lower lube is easily carried out to get you back to prime sensitivity, and pulling the fork to change the air spring from the 160mm travel to 180mm travel showed some seriously high-quality looking internals that had me reassured that they would stand the test of time, going some way to justifying the high price tag.
Where the fork was a little bit tricky to get set up perfectly, the TTX22 coil shock was rather the opposite on the Kavenz VHP16 it spent three months mounted to. Already knowing the spring rate, I needed to get my 30% sag meant it was essentially a case of plugging and playing, and the Öhlins calculator proved to be spot on for the spring rate.
Low Speed Compression tweaks made a notable difference to the feeling of the rear end, providing some quick and easy tuning to tweak the feel to the terrain on the menu for the day. Because there’s not a huge number of clicks availabe to choose from, with a range that feels to be quite wide, it’s easy to feel the difference in handling between each setting, and you’re constantly funneled towards the correct setup without having to make three or four click changes at a time. The majority of the time was spent in the “2” position of the High Speed Compression dial. The “3” position added notable support for smoother terrain and when pedaling, whereas the “1” setting was reserved for the wettest days where ultimate traction was more favorable to support.
The TTX22m.2 proved to be composed and consistent through a whole host of punishment, never giving wallowy sensations or lacking support once compression settings were dialed in. Through long and punishing descents I never managed to create a change in damping effect, though the piggyback did get notably hot to the touch on a few occasions. The bottom out bumper does a stellar job in the absence of a hydraulic bottom out system. Its influence is felt as a progressive ramp up rather than having a harsh and notable edge to it, and so only allowed me to feel a notion of harshness through the pedals on a couple of severe overshoots, rather than regularly whacking a less refined bumper.
There was not so much as a peep throughout testing, with the spring staying in place thanks to the nylon grub screws to lock the collar and the damping remaining quiet and composed. The TTX22 is clearly a high-quality option, and with custom tuning potential at Öhlins service centers there’s no doubt that it’ll work great on most bikes.
The Wolf’s Last Word
Overall, there’s no denying that both of the Öhlins products in question here have the capability of delivering extremely good performance. However, the RXF38 m.2 takes a little more time and energy to obtain a setup which balances all of the positive traits – it’s out there, you’ve just got to find it – whereas the TTX22m.2 requires much less chasing before it delivers its excellence.
RXF38 m.2 Fork – $1,345 / £1,477
TTX22m.2 Shock – $825 / £863