Secus Fork Air Spring Upgrade Kit - Fox & Rockshox Forks
For the first time, we created an air spring with a truly better spring rate, everywhere in the travel, than a coil. The Secus upgrade delivers the first and only air spring system to really come indistinguishably close to the linear spring rate of a coil fork for the entire first 2/3rds of its travel, with the advantage of a gentle end stroke progression to prevent bottoming without the “wall of force” harshness that excessively progressive springs create.
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Secus Advantages:
- An enlarged negative air spring chamber delivers a soft, supple initial stroke for ultimate small bump compliance (yes, even compared to the Luftkappe)
- Proprietary Midstroke Support Valve improves predictability and support beyond the sag point
- Reduced lower leg pneumatic ramp means better scalability of the air spring, particularly for light riders who previously struggled to use full travel
- Plush and predictable like a coil, bottomless like an air spring
- Allows full use of travel in both directions – fully extends to topout without any quibbles (including on Debonair B1 air springs) and fully compresses without excessive ramp
- Allows more lower leg bath oil to be used for superior lubrication
- Considerably lighter than coil conversions – adds approximately 130g
- Simple setup – inflate fork, bounce on it a few times, press MSV charge button, go ride
- Compatible with OEM volume spacers for end-stroke progression adjustment
- Compatible with other aftermarket top-cap systems such as DSD Runt and MRP Ramp Control
- Lower compression ratios mean a more consistent spring rate
- Transferable between any Secus-compatible forks with only a footstud to change at most
Three Stages of Control
By independently optimising the beginning, middle and end portions of the stroke, the Secus gives you the linear-to-progressive spring rate that coil springs and traditional air springs alike wish they had.
Initial stroke – enlarged negative air spring chamber delivers a soft, supple initial stroke for ultimate small bump compliance
Midstroke – where traditional air spring rates drop off in the midstroke, our proprietary Midstroke Support Valve technology boosts the midstroke spring rate to maintain linearity, for support, predictability, ride height and compliance
End stroke – enlarged lower leg volume reduces overall progression even at higher pressures and allows for a wider range of end-stroke ramp options to be utilised with standard fork volume spacers.
COMPATIBILITY:
| Fork | Year & Specification | Secus Variant |
| Fox 32 | 2018+ (unless footnut on spring side is recessed) | Fox A1 |
| Fox 34 | 2018+ (unless footnut on spring side is recessed) | Fox A1 |
| Fox 36 | 2018+ | Fox A1 |
| Fox 38 | 2021+ | Fox A2 |
Fox 40 | 2018+ (Note: Installation tool sold here, air spring is difficult to disassemble) | Fox A3 |
| Fox 32 StepCast | Not Compatible | |
| Fox 34 StepCast | Not Compatible | |
| Marzocchi Z1 | 2019+ | Fox A1 |
| Rockshox Pike / Revelation (2014-2018) | Requires 2019-20 (B1/B2) Debonair Airshaft update to be directly compatible, or you may use the (2021) C1 Debonair Airshaft and replace the sealhead. The BIP (Bananas in Pyjamas) B1/B2 sealheads can be included in the kit by selecting the dropdown option in ‘Tools Required’, and may also be purchased separately here. Secus is not compatible if air side footbolt is recessed in the lowers (some 2018 forks). | Rockshox A3 |
| Rockshox Pike / Revelation (2019-2020) | Compatible unless footbolt on spring side is recessed. No replacement sealhead needed if using stock air shaft (B1/B2). | Rockshox A3 |
| Rockshox Pike / Revelation (2021+) | Requires 2019-20 (B1/B2) Debonair Airshaft update to be directly compatible, or you may use the (2021) C1 Debonair Airshaft and replace the sealhead with the BIP (B1/B2) sealheads. The BIP (Bananas in Pyjamas) B1/B2 sealheads can be included in the kit by selecting the dropdown option in ‘Tools Required’, and may also be purchased separately here. | Rockshox A3 |
| Rockshox Lyrik / Yari (2016-2018) | Requires 2019-20 (B1/B2) Debonair Airshaft update to be directly compatible, or you may use the (2021) C1 Debonair Airshaft and replace the sealhead with the BIP (B1/B2) sealheads. The BIP (Bananas in Pyjamas) B1/B2 sealheads can be included in the kit by selecting the dropdown option in ‘Tools Required’, and may also be purchased separately here. | Rockshox A3 |
| Rockshox Lyrik / Yari (2019+) | Compatible. No replacement sealhead needed for 2019-21 (B1), BIP sealhead is required for C1 air shafts (red footstud) on 2021-22 forks. | Rockshox A3 |
| Rockshox Zeb (2021+) | Compatible. No replacement sealhead needed. | Rockshox A3 |
| Rockshox Boxxer (2019+) | Compatible. No replacement sealhead needed. | Rockshox A3 |
| Any year Rockshox Pike or Lyrik forks with 35mm C1 (2021+ style) air shaft kit installed | Requires Bananas In Pyjamas (BIP) Sealhead to be installed. The BIP (Bananas in Pyjamas) B1/B2 sealheads can be included in the kit by selecting the dropdown option in ‘Tools Required’, and may also be purchased separately here. | Rockshox A3 |
| Rockshox Lyrik (2023+) | Compatible. No replacement sealhead needed. Includes A3 adaptor to replace Buttercups on relevant air shafts. | Rockshox A3 |
| Rockshox Pike (2023+) | Compatible. No replacement sealhead needed. Includes A3 adaptor to replace Buttercups on relevant air shafts. | Rockshox A3 |
| Rockshox Zeb (2023+) | Compatible. No replacement sealhead needed. Includes A3 adaptor to replace Buttercups on relevant air shafts. | Rockshox A3 |
Note: Rockshox A3 fitment kit replaces the previous Rockshox A1 and A2 kits. They all share the same footstud part, but the A2 kit also includes spacer shims to allow for fitment on forks that the A1 kit did not fit. The A3 kit includes the spacer shims plus an adaptor for Buttercup air shafts. Note that the Buttercups will be replaced.