Long Term Thrashing
2020 Öhlins TTX Air & RXF36 m.2 Air Review
When Öhlins released the latest RXF forks they also unveiled their revitalized air shock. The TTX Air is ‘born out of the highly successful TTX22M Coil’ shock, giving it heaps to live up to. The shock uses the 22mm twin tube damper found in the coil shock, also offering the limited external adjustability of the HSC (2 positions with the 3rd being a pedal-assist) while providing 12 clicks of LSC and 12 clicks of rebound.
- TTX22 Damper Technology
- Modular reducer system
- Metric and Trunnion sizes
- Air spring fully serviceable w/o opening damper
- Weight: 524g (230x65 full of spacers w/ hardware)
- MSRP: 780 USD/733.20 Euro
The damper isn’t the only place hiding twin tubes when it comes to the TTX Air. There are two options of the shock available and the larger features a twin-tube air can, providing higher volume in both the positive and negative chambers. Öhlins feels that with multiple stroke lengths and a wide variety of kinematics one size doesn’t fit all and they developed the two variations to better serve customers. With the single chamber air can, only the large puck style volume spacers work but for the larger double air can, smaller clip spacers are provided to offer greater fine-tuning. Max pressure on the small can TTX Air is 300psi while the double is 325psi
Öhlins developed the TTX Air taking full advantage of the metric design. They claim more support and bushing overlap make this a more robust air spring and from my experience, this is accurate. It’s a good thing too after the issues that surfaced with their earlier STX22. With the shock mounted to my GeoMetron G1 (a bike that puts considerable side load into the shock and part of the reason for the spherical eyelet bearings in the bespoke EXT Storia) side load on the shock was bound to be tested.
Setup + Squish Time
When first bolting the TTX Air to my G1, the air can was left as it arrived; with an 8,000mm³ reducer clipped into the main can and two 2,000mm³ reducers in the outer air sleeve. Once happy with ride height I adjusted the dampers to suit, achieving an initial setting to work from. That left me with ~22mm sag (~33%) with the HSC open (Pos 1 on the dial), LSC was initially left open (12 out) and the rebound was 7 out. The first ride was in the Whistler Bike Park and I quickly found I needed more support. The LSC compression was wound in, eventually settling on 4 clicks out and the HSC was moved to position two. Position 2 on the HSC had a notable effect on the shock and I found the rebound needed to be opened, allowing the oil to flow more freely as the heavier HSC setting slowed things down.
Eventually, I settled on 138psi to achieve 20mm sag (30%) and with the largest reducer (12,000mm³) in the main air chamber, the bike held its shape well. I switched between positions one and two on the HSC lever, testing which I preferred more. In the bike park, with the air spring set to a combined 16,000m³ of reducers, I enjoyed more HSC. The bike held a better shape when loading up like a goon in high-speed berms and was composed off lips. On steep, rough trails like Misfire and Delayed Fuse, the extra compression held the bike up during the sharp, repeated hits. Low-speed compression was left at 4 out and rebound settled at 8 out.
Öhlins was vocal about the effort taken to reduce friction and sideload in the system and it's clear on the trail. The TTX Air shock is remarkably smooth, gliding through its travel with ease, while the spring and damper combined offer excellent control and stability. There’s a clear lack of friction from the spring and its initial touch is smooth and easy to initiate. Control of the stroke is great and the shock never feels sudden or stuck. Transitions between compression and rebound felt seamless and the port between the positive and negative springs is indistinguishable leaving no dead spots.
I sometimes feel the pop attributed to air springs is at times stiction in the system. The way air pressure builds when compressed causes it to return quickly but after riding the TTX Air, I’ve found it to be more controlled in this regard. The lack of friction in the shock results in it being very predictable off lips and in rough terrain the rear wheel tracks the ground sensationally. The feel of the TTX Air is similar to a coil in this regard with the smooth, unrestricted movement allowing it to move consistently.
The only way I achieved any unusual or unpredictable traits from the TTX Air was when loading the bike aggressively into a choppy corner or occasionally when tossing the back wheel around like a goon – as you do in the bike park. Each situation produced high shaft speeds and sent the shock deep into its stroke rapidly. With the bike aggressively side loaded, I could feel the shock resisting. Because of the aforementioned side load of the G1, I found the TTX Air to catch in these situations rather than continue to absorb the impact like the stock EXT with spherical eyelet bearings. Hardly the fault of the Öhlins shock but quite noticeable coming from the bespoke EXT Storia built to remedy this situation on the G1.
After a few more rides I wanted more end stroke protection. Adding more pressure took away the soft initial touch and stood the bike too tall for my taste. The remaining two 2,000mm³ spacers were added to the outer sleeve of the air can, bringing the reducers to their max for this shock at 20,000m³. Going whole hog, I anticipated needing to remove one to settle in the middle but found it to work well. The air spring was set to 138psi for 20mm sag (30%) and the LSC was opened to 7 out. With this setup in Squamish, I found myself switching the HSC dial back to position one; the lightest setting.
The amount of progression provided through the stroke felt great and despite the shock being full of reducers, there was no harsh wall or unpredictability at the rear wheel. The build of progression was gradual and controlled, while the damper and effortless glide of the shock continued to provide great grip. Less feedback was felt through my feet when sitting in the mid-stroke, providing a smooth ride and allowing me to focus on the trail when encountering rough, or new terrain. As a flat pedal rider (these days) this was a welcome characteristic to the smooth action of the TTX Air.
RXF36 m.2 Air
A year after mounting the RXF36 m.2 to my G1, the fork remains creak free. Following the m.2 coil review, the spring was switched to the self-contained air spring. The switch is easy to perform at home but the air-sprung fork is sold with a lighter damper tune, so I visited Vorsprung to have the new shim-stack configuration installed. Since then I’ve happily continued to ride the fork through the challenging dry, rough and abrasive conditions I look forward to each summer in Squamish.
- Air and Coil sprung options.
- Coil provides 130–170mm travel. Air is 150–180mm
- 160mm air and coil spring options tested
- Different offset options available:
- 27.5: 46 or 38mm | 29: 51 or 44mm
- 29er 44mm offset option tested
- New TTX18 damper cartridge
- Retrofittable internals
- SKF seals
- Weight: 2,393g (Coil w/ hardware/axle and an uncut steerer)
- 2,149g (Air spring w/ cut steerer and star nut)
- MSRP: 1,250 USD/1,190 Euro
In the coil m.2 review I noted how impressed I’ve been by the structural stability of the RXF36 m.2 chassis and those feelings remain. The front wheel tucks under less during heavy braking, especially in steep, choppy sections and steering accuracy is great. Less flex also allows the fork to activate more immediately and with less chance of friction caused by flex on the system. Öhlins also allows up to a 223mm rotor on this fork and I’ve been testing a brake set with a fruit platter sized front rotor for more than a month with no issue.
The ability to switch between air and coil is unique in the day of primarily air-sprung forks. There are ways to make a coil work in competitors forks – like the aftermarket options from Push or Vorsprung – but much of the time switching back to air isn’t recommended. To do that a new CSU is required, making it a costly transition. While the RXF36 m.2 makes switching back and forth possible, would anyone want to? I struggle to see why but that doesn’t mean it’s not appealing for someone. A scenario that may come up is purchasing a coil option to try but perhaps not getting the ride characteristics hoped for. In this situation, rather than having to buy a new fork or CSU, an air spring cartridge can be purchased for 117.50 USD/103.40 EUR and slid into place.
Öhlins’ air spring is a twin-piston, three-chamber system featuring the main chamber, accessible from the top of the fork, and a ramp chamber accessible from the bottom. Adding air to the main chamber sets the ride height of the fork as it fills the positive and negative air springs. A transfer port handles airflow between the two, as with many other forks, but it’s worth noting that the Öhlins is silent and even focusing on it during setup I’ve failed to notice anything. Heaps of forks are getting better in this regard too but two years ago when I first got a taste of the RXF36 m.2, the clean transfer between positive and negative was a first for me. Where things differ with the m.2 is how riders tune the end stroke. Rather than the puck system we’re more accustomed to seeing, Öhlins use another air spring to tune progression. This presents heaps of tune-ability but can be daunting for riders who don't like to tinker.
As the main chamber builds pressure under compression, the piston of the ramp chamber starts to move, building resistance as it does. It provides a different feel on the trail to the typical puck systems thanks to dynamic changes. A puck system simply increases pressure within the main chamber as the fork is compressed. Because of this, I didn’t notice any “wall” to the ramp, even when experimenting with high ramp and lower main chamber pressures. It’s still possible to achieve an overly progressive bottom end to the stroke but the harshness typically experienced by running heaps of tokens and low pressure isn’t an issue.
Something we’ve heard much of with new suspension releases is ‘increased negative air spring volume’ and that was the same for the new RXF36 air spring. The increase provides improved small bump and the ability to achieve greater mid-stroke support when compared to Öhlins’ previous air spring. These updates were brought across from the development of the World Championship-winning DH38 and combined with minimizing friction in the system, make for a very nice feeling air spring.
Setup + Comparison Time
Setting up the m.2 air differs slightly thanks to its ramp chamber. First, air is pumped into the valve at the bottom of the right fork leg. The initial setup is best done following Öhlins’ recommend start point of double what’s planned for the main chamber. Once at the desired pressure, things move to the top of the fork where air is added to the main chamber. Initially setting the pressure to the amounts recommended on the back of the fork leg is a good starting point but as I’ve found on my G1, I required a lighter spring than the recommendations.
Adjusting the air to suit can take a bit more time but it offers heaps of flexibility, even compared with other air-sprung fork options. Eventually I achieved the static shape I was used to with the coil – which was my benchmark thanks to how good the bike felt overall. That put me at 96psi in the main chamber 184psi in the ramp. Over time I tested offsetting the two, pushing the ramp chamber closer to double the pressure in the main. After a while, I settled on 94psi and 181psi to achieve the ride I wanted but I did drop the ramp down as far as 180psi. This resulted in a very linear feeling fork but I was able to achieve full travel too easily and had nothing in reserve for those ‘oh shit’ moments. With the pressure set back to 181psi, I was able to save the last 10–15mm for extra protection.
Dropping pressure while increasing the ramp chamber salvaged a surprising amount of support in the latter portion of travel while sitting quite deep into the stroke. The mid-stroke support in these situations suffered but it was interesting how rideable it was. I didn’t experience any of the sharpness typically encountered when doing similar using the puck system of other forks. The settings will differ from bike to bike, rider to rider but the point is the air-sprung Öhlins RXF36 m.2 offers incredible tuning flexibility. The air spring provides an excellent ride, moving in and out of the stroke smoothly and taking everything that can be thrown at it. Front wheel grip was excellent and the fork's ability to recover from big hits is commendable. Composure through a series of medium to large hits at speed was also great. The m.2 with the air spring, carried over much of the ride characteristics I enjoyed so much with the coil. I did find that while very tunable, I wasn’t quite able to achieve the mid-stroke support of the 2021 Fox 36 – which can be found quickly too – but compared to the 2020 model they’re equal.
When switching to the air spring, the damper was re-shimmed to a lighter C50 tune from the then stock C60 of the coil-sprung fork. This provided me with an almost identical setup in terms of compression but I did have to open the rebound between one and two clicks with the air spring. I continued to flip between positions one and two out on the HSC dial (pedal platform being 0). The LSC was set to the same position as with the heavier tune in the coil fork. The TTX18 damper found in the RXF36 m.2 does an excellent job of supporting and controlling the bike, transitioning like butter between compression and rebound to provide loads of control and grip. I found it comfortable with both the air and coil springs and never had issues with hand fatigue as a result of the fork. It’s a refined feeling damper offering a usable range at each end of the dials, except for the rebound, which can be slowed to almost nothing for my weight. For heavier riders requiring firmer spring rates, that extra depth from the rebound adjuster will come in handy.
- Bike: GeoMetron G1, size “Extra-Longest"
- Fork: Öhlins RXF36 m.2 Air
- Travel: 160mm
- Sag: 31mm / ~19%
- HSC: 2 Out (pedal platform is 0) / LSC: 12 Out
- Rebound: 13 Out
Once air spring testing was complete, I swapped back to the coil. I prefer the lighter initial touch, which is great with the air spring but not quite as sensitive as the coil. I also find the fork's ability to effortlessly move in the mid-stroke while providing great support, benefits my riding more than the adjustability of the air spring. On top of that, I prefer the coil luxury of not having to check air pressure. Regardless of temperature or elevation, the coil requires essentially zero attention. When switching back to the coil with the lighter compression stack, I stopped into the damper more, settling at 11 out for LSC and adding 2 clicks of rebound, slowing it down from 13 out to 11 (I was twelve out with the stock C60 stack).
Öhlins has updated the stock damper tunes and now the coil fork comes with a C50 tune, the same as I'm currently using, and the air has gotten lighter again; now C40. This allows lighter riders to make use of the range available while heavier or more aggressive riders can still have the control needed. I didn’t have an issue with the C60 tune of the stock coil fork but was sitting toward the open end for several settings. There’s still heaps of room for the fork to be stiffened up so Öhlins going lighter again makes sense. And if the stock tunes aren’t working there’s a large bank of shim stack configurations available.
The Öhlins RXF36 m.2 and TTX Air have performed impressively over a long period. I’ve had no issues with durability and the tune-ability of each has been excellent. There’s less room for a radically wrong setup thanks to the limited range on the adjusters, yet they provide enough for the majority of riders. Damper settings are usable throughout the range and can be set to suit using Öhlins’ large bank of configurations if there’s a need to go outside what’s provided. Grip, support, and comfort have each been great. They are priced higher than some competitors but I’ve found the damper sensational and the new air springs great too. The TTX Air spring felt more refined than the fork but each is at least as good as the competition.
Öhlins has also improved access to product knowledge and now provides service manuals for home techs. Working on the fork and shock, I’ve found each to be relatively easy and a lower leg service on the m.2 can be completed in roughly 15 minutes. There’s also an increasing number of certified technicians available to perform more involved things like a damper tune.
Riders seeking an aggressive suspension package with an unwavering ability to tackle rowdy terrain and still provide great feel in smoother situations will enjoy the latest from Öhlins.
Ape Index: 1.037
Trail on Repeat: Changes as often as my mood.
Current Regular: Every test product spends time on Entrail