Halcyon

Halcyon Zero Gravity Sidemount System

A minimalist sidemount harness and bladder system developed with cave and sidemount divers, pairing with individually mounted cylinders rather than a single backmounted tank.

Wing / backplate

Modular harness and wing, the standard technical-diving setup. Expect to configure backplate, wing, and harness separately rather than buying a fixed jacket.

Halcyon Zero Gravity Sidemount System
2.5Comparison Score
$735
Released2017
Stylewing backplate
Weight-integratedYes
Lift capacity27 lbs
Backplatenone
D-rings—
Trim pockets—
MaterialRF-welded U-shaped bladder, adjustable webbing harness
Travel-friendlyNo
Dry weight—
Fitunisex
Sizes—

"Lift capacity" is the manufacturer-rated buoyancy the wing/bladder can provide at the surface. Match it to your exposure suit, tank, and weighting, not the biggest number available.

Pros
  • U-shaped bladder design keeps the profile low and minimizes drag compared to a backmounted wing
  • Inflator can be mounted on either the right or left side, and the harness supports three "door handle" positioning options
  • Optional weight pouch adds up to 15 lb of integrated ballast without a separate weight belt
Cons
  • Sidemount systems have a steep learning curve and pair cylinders individually rather than using a single backmounted tank, so it's not a drop-in replacement for a jacket or backplate-and-wing BCD
  • At 27 lb lift, it's built for warm-water diving with aluminum 80s rather than steel doubles or heavy drysuit configurations
  • Halcyon doesn't publish a D-ring count or total system weight for this model
Diver community sentiment
Mixed opinions

Genuine diver discussion specifically about the Zero Gravity is fairly sparse compared to Halcyon's older Contour sidemount rig. One experienced Scubaboard poster dismissed it as a half-measure between competing sidemount design philosophies, calling it "kind of meh" and steering buyers toward XDeep instead. A sidemount-focused forum thread showed a more detailed split: the original poster praised the U-shaped bladder for surprisingly good trim and avoiding the "camel hump" bulge common on other wings, while other posters raised technical complaints that the cylinder rails sit directly on the bladder, distorting trim as it inflates, and that the rear dump valve is awkwardly placed and hard to reach one-handed.

Scubaboard: Zero Gravity vs Apeks WSX-45Sidemount Forum: Zero Gravity discussion

Summarized from public forum discussion (Scubaboard, Reddit, and similar), not a survey we ran ourselves. See the linked threads for the original conversations.

The Zero Gravity is Halcyon’s dedicated sidemount harness and bladder system, developed with cave and sidemount divers rather than adapted from a backmount design. Its U-shaped RF-welded bladder sits low and minimizes drag, and the harness supports adjustable bungee routing, a choice of inflator side, and three “door handle” positions for cylinder attachment. It’s built for open-water sidemount diving with aluminum 80s as well as cave configurations with drysuits and steel cylinders, and it’s aimed at divers already committed to a sidemount setup rather than those looking for a single-tank backmount alternative.