Review: Öhlins RXF36 M2 Trail Fork

Function, Details & Features

Chassis

Almost no plastic bits or pieces adorn the fork and all the well crafted metal parts feel solid and tactile. Rubber seals are nestled away in the caps and adjusters to keep the damp and debris from entering the internals. Its stealth black appearance could make it lost in the sea of murdered out forks that are a rider favourite colour at the moment, but the gold lower leg decals and air top cap instantly give it away in a crowd as something else.

Öhlins use a pinch bolt system on their axle. Both the axle and the pinch bolt use a 5mm Allen key to initially tighten the axle and then clamp the lower leg around it. Sure, it takes a tool and maybe 10 seconds more than a QR through axle, but allowing the tolerances of your hub to define where the fork legs sit can introduce unwanted friction by having the uppers compress into the lower legs at an angle rather than directly and smoothly straight up and down. There’s a lot of talk about fancy seals lately, which the Öhlins fork does have, but this small detail goes a long way to ensuring low friction in the system.

The fork chassis uses 36mm diameter stanchions and a redesigned crown, compared to their previous fork, for additional stiffness. Gone is the built-in headset crown race and now there’s a standard diameter ready to accept any and all headset races for tapered forks. Attention was also given to matching the stiffness of the lowers to the crown and steerer unit. Balancing them out helps give predictability from the fork as it flexes around, storing and returning energy. Blue SKF wiper seals sit at the top of the fork and are aimed to reduce friction while still having increased performance in wet conditions.

The fork lowers house a double set of large bushings that are sized to have just the right balance of play and fit to provide a good solid sliding connection while incurring the minimum friction. Tire clearance is also improved over the previous fork with up to 3.2” tires on the 27.5” forks and 2.8” tires on the 29” version - if you’re a fan of bigger rubber then there’s plenty of room. Alternatively, if you’re not, then there’s absolutely tons of mud clearance, which is always welcome as no one likes a bike so clogged up with peanut butter that it stubbornly won’t move.




Spring System

I tested the air-sprung RXF36 (there's also a coil sprung option available), which has some neat little features that differentiate Öhlins from the competition. As is commonly used, there are two chambers handling the main and negative spring. A transfer port allows the passage of air between these two chambers as the fork compresses and rebounds. This auto-equalizing should provide the right balance between the chambers no matter the rider weight and avoid problems for people at the extremes of the rider weight window.

Where things differ and get interesting is in the addition of a third chamber: the ramp chamber. Adjusting the pressure in here affects the ramp characteristics of the fork. Commonly this characteristic is modified with the addition or removal of plastic tokens, changing the air spring volume inside the main chamber. But Öhlins ditched the plastic and use a separate ramp up piston and air pressure to change the behaviour of the fork.



As the fork starts to compress, the volume of the main chamber decreases and the pressure increases. Once the pressure builds high enough the ramp piston begins to move and squish the volume inside the ramp chamber. Having a lower ramp chamber pressure will initiate the ramp up piston movement sooner in the travel and provide less overall force back than a highly pressurized ramp chamber. The beauty of this system lies in the ability to tune more the behaviour of your fork, rather than just the final portion of travel, while keeping the same initial stroke suppleness. Having it adjusted by psi also opens up the adjustment window to finer tuning. Cutting tokens down with a hacksaw is also possible in conventional forks, but adding or removing a psi here and there is even simpler, and the character changes to the fork are nicely perceivable when riding.


The volumes of the main/negative chamber and ramp chamber can also be adjusted with spacers, but this is something to be done by an Öhlins MTB service centre. The pressure adjustment options already on the fork are more than enough for the vast majority of the riding population, but given this extra internal adjustment, Öhlins should be able to get you absolutely dialed in if you or your terrain require something slightly different.

The air spring unit is a stand-alone sealed unit, which can be removed from the fork with minimal effort, readily available tools and no loss to the lower leg bath oil (if you have the fork horizontal). Changing travel can either be done by purchasing a different main air tube for around 35 EUR/USD, a route that requires more work, or a complete air spring unit can be had for 100 EUR/USD and, which takes 15 minutes of easy wrenching to install.



Damping System

Öhlins has been working with twin tube damping architecture for longer than most across the spectrum of genres that they offer products for. Twin tube is as simple as it sounds, with two tubes housed inside each other providing a circulation of oil from in front of the piston to behind and vice versa as the fork compresses and rebounds. The idea behind this concept is to remove any risk of cavitation (a rapid change in pressure that can cause the formation of vapor filled voids, resulting in an inconsistent fluid properties). The experience Öhlins have with this layout means they can precisely manage the pressures over the piston, keeping them within a range then ensures performance.



The RXF36 m.2 has their updated TTX18 damper. TTX refers to the twin tube architecture and 18 refers to the 18mm diameter of the main piston, which happens to be the exact same piston used in the DH38 fork. Again, it’s a stand-alone sealed unit that can be whipped out fast and cleanly for maintenance or setting changes. The main piston houses the low speed adjuster, takes care of rebound damping and also a portion of compression duties. Situated at the top of the fork, above the main piston, is the compression valve which handles only compression duties. High speed compression is controlled with a shim stack, with the external high-speed compression adjuster varying its effective clamp diameter on the shim stack and so controlling its stiffness and damping force. The low speed oil flow is controlled by a bleed needle in the compression valve.

The low speed rebound adjuster, at the bottom of the fork, can adapt to changes in temperature by using the different expansion rates of steel and aluminium. This means that the rebound should stay closer to your preferred setting no matter the ambient and operating temperatures that you put your fork through.


At low compression speeds the oil flows through the bleed valve on the main piston and compression valve. The low speed adjuster meters the amount of oil flowing through the orifice and controls the rider input into the bike, allowing you to find the optimum ride position and weight transfer between the front and rear contact patches regardless of the terrain. When the fork compression speed is high enough the oil starts to flow through the shim stacks on the main piston and compression piston. The higher the pressure, the more the shim stacks will open.

On the rebound stroke, the check valve at the bottom of the damping unit closes and forces all the rebound oil flow through the high and low speed channels of the main piston. High speed flow is controlled by the main piston shim stack and low speed oil flow is controlled by the bleed needle, which changes the size of the rebound bleed opening.

The TTX18 cartridge's standard tune does have less damping overall than the previous TTX22 cartridge. This is still more than what they’ve measured their competitors to have, but they do have a catalogue of 7-10 proven compression and rebound tunes that every service center has access to if you do end up going down the custom tuned route. Basically, the fork is greatly adjustable out of the box, but behind the scenes Öhlins have a huge amount of combinations available, both on the air spring and damping side, ready to go.





The compression adjuster is split into a familiar high-speed outer dial surrounding a low speed dial. The high-speed adjuster has four settings. The first three dealing with adjusting the compression for riding situations and the fourth being a platform to use for long climbs. The low speed compression adjuster has 16 clicks which work across the range of high-speed compression settings.

As is the case with the rebound adjuster, all the compression adjusters have a solid feel to their indents along with an audible click. There are no worries in vagueness in getting your setup dialled or figuring out where you are in the range. Öhlins measure the clicks from the hard stop of fully closed, meaning that all adjustments are from the same reference point.

I started at 110psi in the main chamber, 210psi in the ramp chamber, rebound at 7 clicks and all compression adjusters fully open. I ran the ramp up pressure higher than stated on the side of the fork or in the online setup guide due to the severity of the trails where I were was testing.


Performance

Testing began on the Champéry World Cup track, where’s not really a window of warm up available and you’re straight into it whether you’re ready or not. But, being thrown to the wolves this quickly really shows if your bike and setup have your back with a startling speed.

Having swapped out both the fork and shock for new items provided a bit of a foreign feeling. The smoothness couldn’t be denied, but a bit of knob tweaking was needed to find the sweet spot. Not deterred, and knowing how well each click on the fork translated into a perceivable feeling while riding. I cracked on with getting it dialled in. Some products take a while to get to that setting where you would violently fend off people from moving your clickers as it feels that damn good. The Öhlins only took two shots and we were sucking diesel.

Ride height, traction and bottom out all felt remarkably spot on from my car park setup. But there was a bit of chassis stability lacking. Again, a new shock too made everything a degree more foreign. Rebound was opened a click and low speed compression clicks were added to control the compression stroke a little while allowing the fork to return a little faster.

Traction was there in bundles and built into creamy support when the energy inputs got higher. The fork blended away and it felt like I had a direct connection with what was going on at the ground. I could push hard knowing how much traction was available and that the fork had the support to push back and cradle me like a baby wrapped up in a 100% cotton blanket. I have to be honest - that feeling is addictive.


Morgins, just around the corner from Champéry, is an absolute jewel of riding spots. Behind the scenes it was conceived as a testing ground for bikes, suspension, setups and braveness levels. The tracks were designed to weight and unweight bikes to actually create problems that, through design and tinkering, could then be fixed. There are roots, rocks, huge jumps, wild G-force generating corners all laid out in such a way as to demand a bike be ridden. And when you do, the forced grin on your face lasts for days and is resurrected by even the simple thought of hitting just one of the glorious vert berms.

For Morgins, where I'll typically run a harder and firmer setup, the ramp up chamber was upped to 225psi, and this added bottom out resistance was welcomed on the large gaps and flat landings that ensue if you decide to pull up at the right moment. Added to this spring support, the HSC could be clicked up a notch or two to hydraulically help in those high energy occurrences. In making these changes to handle the upped energy levels no detrimental changes traction and small bump absorption were made. The fork still remained as buttery smooth as ever.

With one end of the spectrum dialled it was time to see if the RXF36 could meet the differing demands of trails less touched by man that are in abundance in the Alps, hiding in plain sight while you ride the chair lifts. The fork was easily softened in compression and ramp chamber psi, retaining that creamy traction and support and letting you really get on with the task of negotiating the thin winding ribbon of single trail without second guessing your fork's behaviour, which is hugely valuable when riding things blind and reacting on instinct.

The adjuster clicks may not win at top trumps but each one of them is useable. Essentially, there is less scope for arriving at a completely shit setup. Each setting has its own characteristic that is easy to feel. The fact that the fork can be so easily tuned from full on Morgins charging to jelly armed last runs of the day out in the podunk middle of nowhere while all the time remaining supple when you need it, supportive when you need it, and most importantly controlled and predictable make its performance mightily impressive.





Final Setups

Flat out hard charging (e.g. Morgins): 110psi in the main chamber, 225psi in the ramp chamber, 8 R, 6 LSC and 1 HSC.

Steep & demanding (e.g. Champéry): 110psi in the main chamber, 225psi in the ramp chamber, 8 R, 6 LSC and 2 HSC.

Steep natural riding (e.g. Bex): 110psi in the main chamber, 225psi in the ramp chamber, 8 R, 8 LSC and 3 HSC.

Rocky, rooty natural single track (e.g. Off the beaten track Châtel, Torgon, Pila & Aosta): 110psi in the main chamber, 210psi in the ramp chamber, 8 R, 10 LSC and 3 HSC.




Servicing

Öhlins recommend a lower leg removal, clean and inspection of bushings and seals and new bath oil (if it’s necessary) every 50 hours. Home mechanics with standard tools and a bit of knowledge can do this no problem.

The lower rods of the air spring and damping unit aren’t an interference fit to the lowers, so you can leave your favourite hammer in your tool box. It makes it super easy to do maintenance on the fork and there have been absolutely no issues with oil loss through the non-interference fit. Every 100 hours or 1-year Öhlins suggest that you have your air spring and damping cartridge rebuilt, new lower leg seals, new bump rubbers and new bath oil. All this should be carried out by an authorised Öhlins MTB service centre.

As mentioned, we upped the travel from 160mm to 170mm and did this by swapping out the entire air spring unit. It took 15 minutes, two standard tools (plus the ones to take the fork off the bike) and lost no bath oil from the lowers. An absolute piece of cake.


Issues

After over three months of hammering, in some of the most challenging terrain and with most of that time spent with the fork’s adjusters wound pretty damn far in to provide a damn firm setup to handle this terrain, we can report a grand total of zero issues. Nothing. Zilch. No leaks, creaks, noises, drops in performance, the slightest hint of getting flustered or getting its knickers in a twist.





How does it compare?

Up until riding the RXF36 a trusty Fox Factory 36 RC2 had been bolted to the front of my RAAW Madonna. Having not put in enough time on a Grip 2 cartridge it’s not fair to attempt to compare it to that, so the still very competent performer, the RC2, is the comparison.

Both forks are flagship models, have brilliant adjustability and are pointed at the same scope of hard riding. Installation, setup, adjustability and serviceability of the Fox are all excellent. It’s easy to fit, simple to setup and adjust to your liking and quite easy to service. But the Öhlins was just that bit easier to set up with its psi-controlled ramp chamber rather than having to go inside the fork and change spacers.

Serviceability is also that bit simpler on the Öhlins, depending on what you want to do. The lower legs are removed without the need for a hammer and the stand-alone spring and damping units make changing travel or swapping out to a differently setup damper a simple procedure. This is also easy to do on the Fox too (especially the RC2), though. Full air spring service is slightly harder on the Öhlins, but this is something they recommend getting done by a service centre.

Out on the trail the performance of the two is also close, but again it was the Öhlins that nudged marginally ahead in compression, rebound and composure. All marginal gains, but when you add them all together for an overall performance feel it’s like someone has turned the volume level down a couple more notches on the RXF36 than the 36. You’re still going the same speed, taking the same risks, but the experience is more controlled, more tactile and overall calmer. So, you then increase the volume level with higher speeds and bigger pulls.

For the weight weenies and keyboard engineers there’s a weight difference of 72g. Weight is an important factor in bikes, but there are far more perceivable factors in a suspension fork than 72g.







Pinkbike's Take

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