Review: Öhlins TTX2 Air Shock

Details & Features

The layout of the TTX2 Air's damper is a little different from its coil counterpart. With the coil, the rebound adjuster is on the bottom of the shock and adjusts the valving on the main piston, whereas the air shock's rebound adjuster is located on the reservoir and controls the oil flow as it passes from the outer tube to the inner one. This layout is more similar to what you'd see on a Cane Creek shock or older versions of the Fox X2.

The low-speed compression and low-speed rebound adjusters both require a 3 mm Allen key to adjust. Opposite them is a high-speed compression lever which can be toggled by hand. It offers two settings for high-speed compression damping, plus a third position that closes off the low- and high-speed damping for a firmer platform for climbing.

The way the high-speed compression adjustment works is a little different to most dampers. Usually, when you turn the high-speed adjuster clockwise, it preloads a spring which in turn holds the high-speed valve shut more tightly. In the TTX, the high-speed adjuster changes the path the oil takes as it enters the shim stack. In the firmer setting, the oil enters the shim stack nearer the middle, so it has a tougher time pushing open the shims to flow past - a bit like pushing open a heavy door from nearer the hinges. The downside to this design is it limits you to two or three high-speed settings (flow paths), but Öhlins say it offers a more proportionate damping response when compared to a preloaded valve which "pops open" at a certain compression speed. This reasoning is not dissimilar to Fox's rationale for introducing their VVC valving, found in their GRIP2 forks and the rebound side of the latest X2 shock.

The air spring on this TTX2 model uses a sleeve to increase the available volume in the positive chamber so as not to make it too progressive with more progressive frame designs. This in turn allows for a slightly larger negative chamber for a softer initial stroke.

The volume of the positive air chamber can be adjusted in two ways: by changing the size of the volume spacer in the eyelet of the shock or by adding or removing volume bands in the sleeve. This is a little confusing, especially as the eyelet spacers aren't marked with their volume and different combinations of eyelet spacer and sleeve spacers could deliver the same total volume, but it does the job of tuning the progression through a wide range. Despite being designed to be more linear than the TTX1, the TTX2 can be made quite progressive with the maximum volume spacers.

The air spring works in a similar way to most others on the market, with an air piston that sits between a positive and a negative air chamber and a transfer port to allow the two to equalise at a certain point in the travel. The air valve on the sleeve can be set to various angles to make it easier to access depending on the frame.

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Seven questions with Öhlins Racing Technician, Terje Hansen

How does the damping compare between the air and the coil shock?

In general, we are using way more damping in coil shocks compared to air shock due to the performance and function of an air spring. [This is because an air spring acts a bit like a damper - it absorbs some energy during compression and turns it into heat - so less hydraulic damping is required.]

It feels like the rebound damping is light and free-moving at slow speeds, but not too fast when returning from deep in the travel. Am I right in thinking it's a relatively linear rebound tune?

You’re correct!, we have chosen a linear rebound damping curve (in all Öhlins products more or less), some bikes need more or less low-speed damping. There’s a lot of comfort and traction win or lost in the right choice of rebound damping. The better of a rider is, the less rebound you need. [Cue every Pinkbike reader running their rebound fully open from now on.]

Do you offer different damping base tunes for different suspension designs or riding styles?

The setting that the shock comes with, in the box, is something we have tested on a lot of different bikes and we feel we have made the best compromise with our choice to fit as many bikes as possible. With the external clickers, air pressure and volume spacer you as a customer would come a long way in chase of the perfect performance of your suspension

With the coil shock there is a setting bank for service centres to adjust the base tune via shims to suit different bikes - is the same true for the air shock?

Yes, you could easily do a setting change at an Öhlins service centre if it’s needed to adapt more to your weight, riding style or if you had the shock on one frame model and then you change to a bike that requires a different setup due to different leverage and anti-squat. Öhlins provides setting banks for every product category we make to the service centres to help them choose a setting they might need.

How can I tell what size of volume spacer I have in the eyelet end of the shock? They don't seem to be marked?

No, and that’s something we are working on, attached is a chart of spacers on page 11.

Does the firmness of the climbing mode depend on the LSC adjuster position, or is it independent?

They work independently on the TTX Air.

You no longer make the single-tube STX shock, right? What do you see as the main advantages of twin-tube over a single tube for an air shock?

The main advantages with TTX technology is the adjustability from the external adjuster, more responsive and controlled buildup of damping which gives the riders a controlled behaviour of the bike.

Why does the TTX air have the rebound adjuster at the head of the shock while the coil has it at the eyelet?

The TTX Air has a solid shaft and a different position for the one-way valve compared to TTX 22 M [coil] and therefore it’s possible to have the rebound adjuster in the head.

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Setup



Performance


I did sweeps for all the adjusters (testing from fully open to fully closed on the same section of tack) and the range isn't super wide. Even with everything fully closed, it's still totally rideable (if too damped for my liking). So if you're the kind of person who prefers (or you think you prefer) a really damped feel, or if your bike has a very high leverage ratio, you may need to get a firmer base tune than stock. At the other end of the scale, the shock is pretty hard to ride with the rebound fully open (at least with the pressure and bike I'm running it with) as it tops out all the time. That means for lighter riders or bikes with lower leverage ratios, there should be scope to get it running fast enough for most people. While the range of adjustment isn't massive, I'd say it's well-judged for teh majority of riders in the middle part of the bell curve.

The recommended setup is quite progressive. Running 28% sag (202 psi) I was only using all the travel on the biggest landings like tagging the landing of a large stepdown. A small difference to pressure/sag makes a big difference though - 195 psi allows the use of all the travel more regularly and is noticeably softer. My optimum window was in the 190-202 psi range. I tried removing a volume spacer from the air sleeve, but overall I preferred using a touch more sag and generous progression to add resistance towards the end.


The compression adjustment is usable for me at either extreme, but you can use the low-and high-speed compression adjusters to meaningfully fine-tune the support and balance of the bike. Depending on the shock tune, I often find the LSC adjuster on a RockShox SuperDeluxe adds too much harshness on small bumps before it makes a meaningful difference to chassis stability, so I often tend to run it fully open. Whereas the TTX seems to make more of a difference to stability relative to small-bump harshness.

Having to get a tool out to adjust the low-speed damping can be a pain, but I regularly used the HSC lever to pick between the two settings (1 for steep and natural, 2 for jumps and berms). There's something to be said for a simple choice of two distinct positions over a range of twenty-something barely distinguishable clicks - you're more likely to actually use the adjustment if it's tool-free and easy to keep track of. That said, the two HSC settings aren't wildly different and I wouldn't mind a third HSC setting (like you get on the DH lengths of the coil version) in addition to the climbing mode.

Speaking of which, the climbing mode is a nice balance between firmness and comfort. I'd say it's firmer than the climb switch on a Fox Float X2 but softer than most SuperDeluxe tunes. It makes the bike sit up noticeably higher at the rear and cuts pedalling oscillations nicely when sated, yet still allows the suspension to do its thing when the terrain gets rough. It's ideal for off-road technical climbing. The firmer setting found on most SuperDeluxe shocks (again, the firmness of the RockShox climb mode firmness depends on the shock tune) is better for out of the saddle pedalling and tarmac climbs. Plus, in my opinion, the more unsubtle lockout means you're far less likely to leave it on accidentally for a descent because you're aware of the lockout the whole time. It's up to you what kind of lockout you prefer, but the TTX offers a middle of the road setting.

The shock naturally sits a couple of millimetres into its stroke and extends slightly when the rear wheel is lifted off the ground. The same is true of a Float X2 but not so much a SuperDeluxe, which sits more forcefully against its top-out bumper. In theory, this helps the rear end feel a little more ground-hugging on super rough tracks when the rear wheel is regularly reconnecting with the ground because there is no preload force to overcome before the shock can start moving. But there's no mistaking the TTX air for a coil shock; it's a little stiffer when moving through the first part of the travel and that makes it a little less settled into its travel and stable than a coil shock. I wasn't able to measure the spring curve like I've done in the past but I'd say it feels similar to a SuperDeluxe with a standard air can, though not as linear as that shock fitted with a MegNeg air can.

Damping consistency is hard to say too much about without testing on a damper dyno, but I didn't notice any harshness or bucking towards the end of long descents as I have with some air shocks.


How does it compare?

I've been comparing the TTX to its main rivals throughout this review to try and provide as much context as possible, but during testing, I rode it back-to-back with the RockShox SuperDeluxe Ultimate the Privateer came with. That shock was running the stock LNL1 damping tune and standard (not Megneg) air can.

Comparing shocks is particularly tricky because there are so many variables (suspension design, damping tune and setup). But in this case, I would say the TTX feels a bit more controlled on the big stuff (landings, big compressions etc.) while still being at least as supple over the small stuff. In fact, if anything I felt a touch less harshness through my feet through rough chatter despite testing the TTX with the HSC in setting 2 and the LSC on the SuperDeluxe fully open.

I put this down to the more linear damping tunes making the TTX feel more controlled on big stuff yet suppler on the small stuff, but that's just a hypothesis. Could the SuperDeluxe perform better with a different damping tune installed? Almost certainly. But one advantage of the TTX is the ability to change the HSC damping with a flick of a switch. On the other hand, the option of the MegNeg air can is a big advantage in RockShox's favour, particularly for more linear suspension designs, as it offers a more stable, supportive and supple-off-the top feel. So with a bit of fettling, the RockShox could be as good if not better. As always, suspension performance is 90% about setup.

Speaking of which, RockShox's sag markings, tool-free adjusters and the single type of volume spacer all make it a bit easier to set up.

Servicing


Not that many people pay them any attention, but the recommended service interval on the air sleeve is 100 hours, which is on par with other air shocks. You can do it at home but you will need a shaft clamp as well as the service kit and lubricants.


For a damper service, you'll likely need to send it to your local Öhlins service centre.

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Issues


I had one shock which was reluctant to equalise due to a partially blocked transfer port. This meant if I dropped the pressure the shock would "suck down" into its travel and if I increased the pressure it would top out, even after trying to equalise the spring pressures. That shock was sat in a cupboard waiting to be tested for over six months (fully pressurised) so perhaps that has something to do with it. I asked my local suspension tuner (Sprung Suspension) if they'd heard of similar issues with the TTX air and they hadn't. A second shock had no such issues, and the same is true of a TTX1 air shock I have been riding on a YT Izzo. But right out the box, the TTX is quite tricky to equalise. You have to cycle the shock very slowly to find the point where the air passes through the transfer port and there isn't the loud hiss you get with other air shocks. I'd recommend over-pressurising the shock, then equalising it before checking the pressure has gone down so you know air has moved into the negative.

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Pinkbike's Take