Öhlins' New RXF 36 Trail & TTX Air Shock

Öhlins first entered the cycling world as part of an exclusive partnership with Specialized. While they still work together and co-sponsor World Cup DH and Enduro teams, the brand has since transitioned to provide aftermarket products. After a few years in the market, Öhlins has a new RXF 36 fork and air shock.

The new products send a clear message that MTB is a key category for Öhlins. These aren’t merely tweaks to current items* and they note that much time was spent stressing over the fine details. Öhlins engineers learnt a great deal from the development of the DH fork and the previous air shock, which they admit to having problems with early on. The brand feels that encountering and solving these issues led to better performing products — we all live, learn, and improve, after all.

*Despite the RXF 36 Trail's exterior similarities, it too was reworked in addition to the completely new internals.

Minimizing friction was important for Öhlins. Optimal tolerances, improved seals and surface treatments have been used to improve glide. Rear suspension engineer Andreas Pettersson noted that minimizing friction both improves durability and delivers a better performing product. They were also looking to lighten fork damping, a consistent criticism of the early versions.

Öhlins RXF 36 Trail

Don't be fooled by the 'trail' moniker; this is Öhlins heavy-hitting single crown fork, suitable for the world’s best enduro racers or riders looking for something that can take a beating. It has a similar appearance to the current RXF 36, with 36mm diameter stanchions and their 15mm bolt through axle system, but the chassis has been beefed up.

Highlights

• Air and Coil sprung options. Air provides up to 180mm travel. Coil up to 170mm
• Different offset options available. 27.5: 46 or 38mm | 29: 51 or 44mm
• New TTX18 damper cartridge
  
• Increased Wheel Clearance. RXF 36 29: 29x2.8 / 27.5x3.2 | RXF 36 27.5: 27.5x2.8
• Retrofittable internals
• SKF seals
  
• MSRP: 1125 USD/1140 Euro
  

The current RXF 36 has been praised for its structural stability but Öhlins wasn’t satisfied. The new model is even stiffer, with a redesigned crown that increases overlap at the steerer. Preventing creak is one goal, but the improved structural stability should also provide a better performing fork. That’s if everything else was to remain equal…

The new Trail forks move away from the open system of Öhlins' current 36 and instead house a closed cartridge system similar to the DH fork. Piston diameter in the damper has also been reduced to 18mm, from 22mm. They have realized mountain bike forks don't need the heavier damping provided by the 22mm damper piston. The smaller piston is claimed to be more sensitive too, thanks to quicker pressure build up offering more refined and effective adjustments. It also generates less friction.

Working with the Specialized Gravity DH team revealed the need for less fork damping. Thanks to Öhlins experience in motorcross, they already had plenty of data on what differing oil weights and damper diameters would do. They also knew they wanted even more control over the damper, which meant retaining the shim stack setup. This ruled out switching to a lighter weight oil.  

Changing to the 18mm diameter damper piston, I found I needed to tune the dial deeper into the settings. Like the current RXF 36, the new fork features high and low-speed compression, and rebound damping. The HSC circuit works similar to a climb, trail, descend adjustment, with the open position serving as the general setting for trail riding. Closing the HSC actually shuts down the LSC as well, but it’s done from the HSC adjuster dial.

The LSC and rebound are where most of the external damper setup is done. Öhlins believes that all suspension should be custom tuned and optimized for the customer. Getting the appropriate HSC setting should be possible, albeit likely requiring shop time for a few riders not covered by the stock tune. Tuning the air spring is different to the big players. Rather than focusing on the self-adjusting positive/negative chamber and using pucks or tokens to amend the end stroke, Öhlins relies on air to adjust the bottom of the stroke. This offers lots of user customization and can be done with only a shock pump, but it can take a little more time to get familiar with*.

*Starting with double the pressure in the ramp chamber works well to begin with

To provide increased durability and better glide, Öhlins has used a new surface treatment for the CSU. The bushing inseam has also been polished to reduce friction, but perhaps the most interesting is the bushing play. While many consumers don't like to feel play in a ‘parking lot test,’ Öhlins note that it's important for performance. They’ve worked closely with their downhill and enduro teams and the bushing play in the new RXF 36 Trail is based on team preferences.

This update continues down the path of increasing durability, providing greater lubrication and improving trail feel. Riding the fork, the small amount of play wasn't noticeable, but the effort taken to reduce friction certainly was. Brand new with no break in time, the fork felt light off the top with minimal break-away force required. Movement throughout the stroke was remarkably smooth and consistent, with the front wheel hugging the ground. Despite riding unfamiliar terrain in damp conditions, there was no deflection from the stout chassis.

Öhlins also updated the air spring in the new fork. While they note simply increasing the negative chamber’s size isn’t the end solution, they ultimately have with the new fork. They also looked to improve internals to provide a more sensitive fork. The main piston's ring design and material have been changed to reflect those used in their esteemed motocross racing program, a change that's claimed to reduce breakaway and pressure buildup at higher speeds. They also updated the dividing piston from a cup to a stud design, reducing twisting against the shaft and housing. This should also result in reduced friction.

Current RXF 36 owners are being looked out for too, with Öhlins making the internals available for retrofits. Improvements to the chassis aside, older fork owners can get most of the updates in their current fork. The RXF 36 Trail will also be available in a coil outfit, adjustable between 140 and 170mm with the appropriate spring. No time was spent on this option, but the goal is to pit both against each other when the test products arrive. Stay tuned for that.

Öhlins TTX Air Shock

Öhlins is also releasing a new air shock, the TTX Air. As the name suggests, the shock includes twin-tube technology* and it’s their answer to heavy hitting air shocks. They were upfront about their problems with the STX shock and note that they learnt a lot from the situation. Part of that was moving to a new manufacturing facility in Taiwan. Now they have a dedicated space, with their in-house engineers and staff. With this, they’re confident that their air shock problems are in the past.

*Öhlins originally developed the twin tube technology and brought it to MTB via Cane Creek

Highlights

• TTX22 Damper Technology
  
• Modular reducer system
  
• Metric and Trunnion sizes
  
• Air spring fully serviceable w/o opening damper
  
• Weight: 410 grams (210x52.5 Stumpy Shock w/ all hardware)
  
• MSRP: 780 USD/702 Euro
  

As with the new RXF 36 Trail, minimizing friction for improved traction and feel was the focus. All the new technology used to chase this with the fork is present in the TTX Air shock with the addition of a new grease being developed to improve dynamic lubrication. Time was also spent improving the transfer port design and how it functions, an important piece of the puzzle. A less than optimal design creates a noticeable dead spot felt across the port and Öhlins' updates here were noticeable. There's little noise from the port noticed while cycling the shock during setup and minimal feel from it too. The shock felt remarkable on the trail and was both smooth and consistent. No noticeable quirks were encountered during the short amount of time spent riding it.

Similar to the TTX22M coil shock and RXF forks, the damper offers plenty of low-speed compression and rebound adjustment, while the high-speed compression consists of three settings. Rather than offer lots of clicks, which Öhlins feels are redundant, the TTX Air provides an adjustable range with changes that are apparent. To prevent accidental setting changes adjustments are made with a 3mm hex-key. Unlike the new fork, the TTX Air keeps the 22mm damper piston of the TTX22M coil shock.

Why keep a 22mm piston diameter in the rear shock but move to a smaller, 18mm option in their forks? Ultimately, it comes down to leverage ratios. Öhlins notes that forks work off a ratio below 1:1 while rear suspension is generally greater than 2:1. With this, they feel the 22mm piston in their rear shocks provides the performance they desire. 

Another lesson learnt from their early STX shock was that of side-loads in mountain bikes. They discovered that in extreme circumstances, some bikes rely on the shock as a structural part of the frame. The TTX Air shock has been developed with this in mind. In order to achieve the robustness that Öhlins is after, TTX Air shocks must pass a durability test that they say consists of 100,000 cycles before any air passes the seal.

The TTX Air features a volume reducer system similar to the competition. Deflating the shock, opening it with a strap wrench, and removing or clipping another puck over the shaft allows users to adjust the final third of the stroke. There are ten possible setups in the regular aftermarket shocks, but those with Specialized Stumpjumpers will have only four options. Öhlins developed a specific shock for their partners at Specialized and thanks to the suspension on it, a smaller can needed to be implemented.

Serviceability is something that is important to many and Öhlins appears to be on the same page. The TTX Air shock can undergo an air can service without a need to disassemble the damper side, something that should have quality shop mechanics and home wrenches excited. On top of that, it appears to be a very straightforward process to complete.

My time on the new suspension was spent on a Stumpjumper. The shock was left with the stock, small reducer in the can but I wondered how it would feel without it. Traction from the TTX Air was great, with the lack of friction from the system immediately evident—the single reason I’ve mentioned it so many times. But I found the added confidence got me in trouble when loading up into short, sharp corners. One in particular repeatedly spat me out hard after pushing deep into the stroke. On the exit, I continually rimmed the rear wheel on a rock until I adjusted the pressure. Rebound adjustments didn’t completely remove the issue yet hindered tracking elsewhere. If more time were available on that bike, the reducer would have been removed to see how it performed without.

Öhlins mentioned, mostly in passing, that a goal with the new products was to reduce friction. In the short time had on the new suspension, I can confirm they’ve done an excellent job of this. But how will it relate to durability? Will the updates to the fork survive the test of time? Long-term reviews are needed and thankfully, or not, depending on who you are, the product will become available right as the worst weather of the year hits in the Northern Hemisphere. The timing couldn’t be more perfect.

Visit the Öhlins website for more on the new products and stay tuned for full reviews in the future.