Suspension school · Brand-Specific Technology

Öhlins: TTX Dampers and the Three-Chamber Air Spring

RXF m.2 vs m.3, and why the fork has two air valves

Öhlins builds its mountain bike range around two ideas from its motorsport background: twin-tube TTX damping and a three-chamber air spring. Both reward understanding, because an Öhlins fork is set up differently from anything else in this section.

The Three-Chamber Logic

• Main chamber: sets sag and overall support, filled through the first valve
• Negative chamber: self-equalises from the main chamber and controls initial sensitivity
• Ramp-up chamber: a separate chamber with its own valve that replaces volume spacers, where pressure sets end-stroke progression

Öhlins' guidance puts the ramp-up chamber at roughly double the main chamber pressure, which for typical rider weights works out around 90psi above the main chamber. The beauty of the system is tuning bottom-out resistance with a shock pump in 10psi steps instead of opening the fork to fit tokens.

TTX in One Paragraph

In a twin-tube damper the oil circulates between two concentric tubes through the external adjusters, and the design keeps oil pressurised on both sides of the main piston. That resists cavitation, the momentary foaming that makes conventional dampers fade and feel inconsistent, so the damping stays predictable on long, rough descents.

RXF38 m.2

• Enduro fork, also a common fitment on high-end eMTBs
• TTX18 twin-tube cartridge with 15 clicks of low-speed compression, a three-position high-speed compression lever and 15 clicks of rebound
• The firmest HSC position acts as a climb setting
• Three-chamber air spring with a second valve for the ramp-up chamber

The m.3 Generation

• RXF36 m.3 (January 2025): new lowers with greater bushing overlap, a retuned air spring, a spring booster sealing the lower legs' air volume, and TTX18 clicks revised to 16 LSC, 3-position HSC and 16 rebound
• RXF38 m.3 (2025): a lighter C30 compression tune, micro-polished stanchions, the spring booster, and an air spring that can be removed without dropping the lowers
• There is no m.3 version of the RXF34: the m.2 continues with the lighter OTX18 damper derived from the TTX18

Shocks: TTX22m and TTX Air

The TTX22m is the twin-tube coil shock, now in m.2 form with 16 clicks of low-speed compression and 7 of rebound. Trail lengths get a three-position high-speed compression lever whose third position is a climb mode, while DH lengths swap that for three descending positions.

TTX Air comes in TTX1Air and TTX2Air forms, the TTX2 using a larger twin-can volume for a more linear feel. The 2025 TTX2Air m.2 moved from an internal floating piston to a bladder and carries its climb function on the final click of the HSC adjuster.

Setup Order

• Set the main chamber for correct sag first, ignoring bottom-out for now
• Set the ramp-up chamber to roughly double the main pressure as a baseline
• Ride, then adjust ramp-up in 10psi steps for bottom-out control
• Only then fine-tune compression and rebound clicks