Coil spring or air spring? When it comes to suspension performance, that debate has been raging for years. Coils tend to offer smoother travel with less friction, but air springs are more adjustable and lighter weight.

Countless companies (including Vorsprung) have come out with air spring systems that promised a coil-like feel, but this time Vorsprung is claiming that they’ve created an air spring system with a spring rate that is better than coil. And it’s called the Secus.

Vorsprung Secus negative air spring reservoir for suspension fork side profile

At first glance, you’d probably think the Secus is meant for a rear shock since it looks like a piggy back reservoir you’d find on more capable shocks. But in this case, instead of being part of the damping circuit, this reservoir attaches to the air spring of your suspension fork.

Vorsprung Secus negative air spring reservoir for suspension fork on fox fork

Attaching to the bottom of the fork, and hugging the front brake caliper, the Secus act as an enlarged negative air spring chamber to offer true coil-like small bump compliance. According to Vorsprung, air springs have never quite offered this in the beginning and middle of the travel because “whenever the initial stroke stiffness was reduced, the ending stroke progression was increased – eventually creating a practical limit on negative chamber size.” 

Vorsprung Secus negative air spring reservoir for suspension fork spring rate curve

The Secus eliminates that limit, and has allowed Vorsprung to craft a spring curve that claims to offer ideal small bump compliance while still improving on midstroke support thanks to their MSV (Midstroke Support Valve). The enlarged lower leg volume continues to reduce overall progression, even at higher pressures.

Vorsprung says this allows you to fine tune your end-stroke ramp to your liking with the stock fork volume spacers. Also, since the Secus is located at the bottom of the fork, it’s also compatible with aftermarket ramp control devices like the DSD Runt and MRP Ramp Control.

Vorsprung Secus negative air spring reservoir for suspension fork flat

The Secus also claims to allow you to use more lower leg bath oil for improved lubrication. Even though the Secus weighs about 130g, the weight penalty is less than that of a full coil conversion and it allows for more adjustability.

Secus Advantages (From Vorsprung):

  • Distinctly improved small bump compliance, particularly in the early travel (yes, even compared to the Luftkappe)
  • 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
  • Considerably lighter than coil conversions – adds approximately 130g
  • Allows more lower leg bath oil to be used for superior lubrication
  • 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
  • Transferrable between any Secus-compatible forks with only a footstud to change at most

Secus Disadvantages:

  • Costs more money than not having it
  • 130g is still more than 0g
  • Can be damaged if you have it, can’t be damaged if you don’t
  • Still has seal friction like any air spring – since we use the factory moving seals, friction is unchanged
  • Bottom out control is not externally adjustable – need to use volume spacers which still entails removing the top cap

Vorsprung Secus negative air spring reservoir for suspension fork out riding

Initially, the Secus will be compatible with certain forks from Fox and RockShox. Vorsprung says that this is transferable between compatible forks with only a footstud swap, so it seems fairly easy to install.

Compatible Forks

  • Most Fox forks with Float NA2/Evol air springs (except StepCast forks or forks with footbolts recessed in the lowers). 32/34/36 available immediately, 38 and 40 fitments coming soon.
  • Most Rockshox Debonair 2019-21 forks or prior year forks updated with 2019-20 Debonair air shafts. Pike, Revelation, Lyrik, Yari available immediately, Boxxer fitments coming soon.
  • Not currently recommended for use with 2021 Debonair C1 shafts due to inadequate topout control and incorrect overall length – 2021 forks need to be retrofitted with the Debonair B1 air shaft assemblies from 2019-20.
  • For full compatibility information, see website.

Vorsprung Secus negative air spring reservoir for suspension fork from the back

The Secus will retail for $425 CAD (about $320 at time of publication) which includes free shipping in North America plus a 12-month crash replacement guarantee. Their first batch is shipping now. 

vorsprungsuspension.com

5 COMMENTS

    • or maybe its because the helm air spring isn’t configured in a way that’s compatible with this because of how the neg air chamber can be set independently. while that does improve initial stroke compliance on the helm, it won’t be to the degree that’s achieved on the secus (by increasing the neg air chamber volume).

    • Or maybe it’s because there aren’t enough helm forks on bikes to make it worth the effort to engineer and make this whole assembly for the 5 people who would buy them.

    • Def not an expert by any means, and I don’t even have experience with the Helm. But…last review I read about the Helm, compared to the Lyric and Fox 36 Grip 2, the Helm suffered on small bump compliance as well as support through the mid stroke, and bottom out resistance. Not exactly a winner in their eyes.

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