Karman S-ERGO ATX Active Lightweight Wheelchair — Extreme Agility. Real Rigidity. Fully Adjustable Fit.

If you’re shopping for an active lightweight wheelchair that feels fast, responsive, and built around you (not the other way around), the S-ERGO ATX was designed for exactly that. This chair is made for people who want to move confidently—through tight indoor spaces, busy sidewalks, daily commutes, and real life—without dragging extra weight or fighting a frame that doesn’t fit their body.

With a 15.4 lb starting frame weight, aircraft-grade aluminum construction, a globally patented S-Shape seating frame, and a deep range of adjustments (center of gravity, seat height, back angle, fork, and unlimited footplate angle), the ATX is a true active wheelchair that can be dialed in for performance, posture, and comfort.

Why the ATX Is The Best “Active Lightweight Wheelchair”

Most “lightweight” chairs still feel bulky, flexy, and slow when you push hard. The ATX takes an “extreme design” approach with unique multi-geometrical cross bars that increase rigidity and agility while keeping the chair compact. Translation: more direct power transfer, a more controlled ride, and handling that feels sharp—especially when turning, accelerating, or navigating tight areas.

Built for active users who care about:

• Efficient propulsion (less energy wasted in frame flex)

• A compact footprint that fits real-world spaces

• A frame that can be tuned to your pushing style and balance

• A seating shape that supports a more natural posture

Standout Performance Features 

1) 15.4 lb Starting Frame Weight (Ultralight Category)

The ATX is engineered to reduce the weight you lift, load, and propel—key for anyone who transfers often, drives, or needs a chair that’s easier to manage day-to-day.

2) Patented S-Shape Seating Frame (Signature S-ERGO Benefit)

This globally patented frame shape is designed to support a more ergonomic seated position, helping reduce the “hammock” feel some standard sling setups can create over time.

3) Adjustable Center of Gravity (COG)

This is one of the defining features of an adjustable lightweight wheelchair. By adjusting balance, you can tune the chair for:

• More stability (safer, steadier feel)

• More responsiveness (easier to pop curbs / maneuver—advanced users)

4) Fully Adjustable Footplate Angles (Unlimited Angle Adjustment)

Whether you need a steeper knee bend, longer leg extension, or a specific ankle position, the ATX gives you flexibility to set leg positioning the way your body needs it.

5) “Dialed-In” Fit Adjustments (Not Just One or Two Settings)

The ATX includes meaningful adjustment points across the setup:

• Seat height adjustments (front & rear)

• Back cane height + angle adjustments

• Front fork adjustability

• Tension-adjustable seat and back sling

Key Features at a Glance

• Ultralight starting frame weight: 15.4 lbs

• Frame material: 6061 T-6 aircraft-grade aluminum

• Globally patented S-Shape seating frame

• Adjustable center of gravity (active balance tuning)

• Seat height adjustable (front and rear ranges)

• Back cane height & angle adjustable

• Back cane angle options: 85°, 90°, 95°

• Front fork adjustable

• Unlimited footrest/footplate angle adjustment

• Tension adjustable seat & back sling

• Flip-back armrests

• One-piece foldable footplate (standard)

• Footplate height adjustable (unlimited increments)

• Metallic Aegis-treated high gloss paint

• Available colors: Fashion White, Diamond Black

• Images may show optional accessories (e.g., Spinergy wheels, Kenda tires).

Who This Active Wheelchair Is Best For

Best for:

• Active manual wheelchair users who want speed + control

• People who value a rigid, responsive feel with compact handling

• Users who want an adjustable lightweight wheelchair that can be fine-tuned

• Individuals who transfer often and want a chair that’s easier to lift/manage

• Anyone upgrading from a basic chair to a true active lightweight wheelchair

Not ideal for (typically):

• Users needing very high weight capacities beyond 275 lbs

• Those who require a heavy-duty bariatric frame or specialty tilt features

Fit & Sizing: Choose the Right Setup 

For an active chair, fit is everything. The ATX offers multiple seat widths and depths so you can match your body and propulsion style.

Available seat widths: 14″, 16″, 18″
Available seat depths: 16″, 18″

Quick fit guidance
If you want easier indoor navigation, a narrower width often helps.

• If you want more stability and support, correct seat width and depth matter more than “going bigger.”

• If you’re between sizes, consider your hip width, winter clothing, side guards/armrest needs, and transfer preference.

What Makes It Feel Different in Real Life

A lot of chairs look similar on paper—until you push them daily. The ATX stands out in the areas active users feel immediately:

• More rigid frame response = less energy lost and a more “connected” push

• Compact structure = easier navigation in real environments

• COG adjustability = you can tune the ride from stable to sporty

• Ergonomic frame shape + tension slings = the setup can be customized for your comfort and posture preferences

FAQ: 

Is the 15.4 lb weight the total wheelchair weight?

No—15.4 lbs is the starting frame weight. With standard options, the ATX is typically 26–30 lbs, depending on configuration.

Is this considered an “active wheelchair” or a standard lightweight chair?

This is an active wheelchair (HCPCS K0005 category), designed for performance, adjustability, and responsive handling—very different from basic transport/lightweight chairs.

Does it fold for transport?

Yes. It has a folded width of 14″, plus a one-piece foldable footplate to make storage and loading easier.

Can I adjust the balance so it doesn’t feel tippy?

Yes. The center of gravity is adjustable, which lets you tune for more stability or more agility.

Are the footplates adjustable for leg angle or special positioning needs?

Yes—this is a highlight of the ATX. The footplate angles are fully adjustable with unlimited angle adjustment, and the footplate height is adjustable in unlimited increments.

What seat sizes are available?

Seat widths: 14″, 16″, 18″
Seat depths: 16″, 18″

Are the wheels in the photos included?

Some images may show optional accessories (like Spinergy wheels or Kenda tires). The chair can be configured, and components may vary by setup.

Does it include armrests?

Yes, the ATX includes flip-back armrests, helpful for transfers and positioning.

What does the Aegis-treated finish mean?

The ATX includes a Metallic Aegis-treated high gloss paint, and versions may include Silver Aegis-treated components intended to help resist bacteria on treated surfaces.

Bottom Line

The S-ERGO ATX is built for people who don’t want an “average” chair. It’s an active lightweight wheelchair that blends ultralight engineering with serious adjustability—so you can fine-tune posture, balance, leg positioning, and ride feel to match your lifestyle.

If you want an adjustable lightweight wheelchair that looks bold, feels rigid, and moves like an extension of your body—not a burden you push around—this is the category of chair that changes daily life.