Precision is the point. · The official US home of Dirtlab

One frame.
Two ways down.

We engineered a gravity bike so right it didn't need a motor to be the best on the mountain. Then we gave you the option anyway.

Iuhu CP — same frame, pure pedal Paratu CP — same frame with the Maxon AIR S motor

One frame. You pick the effort.

Same geometry. Same trail manners. Same soul.

IUHU CP — Pure pedal. Pure feedback.

Drag to electrify →

Engineering

Three systems. One obsession.

Every Dirtlab frame is shaped by three named systems — how it moves, how it sits, how it fits you. Here's the lowdown on each. Tap Lab on any of them and we'll overshare.

K-VOLVE K-VOLVEKinematics

How the bike moves

K-Volve is our suspension kinematics — the way the rear end travels, pedals, brakes and soaks up hits. Tune it right and the bike feels calm, efficient and planted, and you never have to think about why. That's the point: the engineering disappears and the ride is all that's left.

K-Volve — Kinematics Evolution

What it governs
  • Axle path — the arc the rear wheel travels. A mildly rearward path lets the wheel move back and up into square-edge hits instead of fighting them.
  • Anti-squat — how much the drivetrain resists the bike squatting under power. The lever that lets a bike pedal hard without bobbing.
  • Anti-rise — how braking forces load the suspension. Keeps the chassis composed instead of pitching forward when you're hard on the brakes.
  • Chain growth & pedal kickback — how much the chain tensions through travel. Kept moderate so impacts don't yank the cranks back under your feet.
  • Leverage curve — how shock force changes through the stroke. Sets small-bump suppleness, mid-stroke support and bottom-out feel.
  • Ride frequency — the suspension's natural “tune.” Balances calm when you're seated against support when you push.
  • Geometry stability — how much wheelbase grows through travel, so handling stays predictable deep in the stroke.
The design ethos

We run a concentric main pivot with a horizontal shock — no idler, fewer moving parts, less friction and noise, more predictable service. Simple where it can be, deliberate everywhere it matters.

And we tune the whole curve, not one headline number. The brief every time: efficient but never nervous, calm but never dead.

G-VOLVE G-VOLVEGeometry

Where you sit, how it steers

G-Volve is our geometry — the angles and lengths that decide whether a bike is stable when it's steep, quick when it's tight, and balanced when you're climbing. Geometry is the one thing you can't upgrade after you buy it, so we solve it first, before anything else gets designed.

G-Volve — Geometry Evolution

What it governs
  • Head angle — front-wheel stability at speed traded against quickness in tight, low-speed turns.
  • Effective seat tube angle — a steep, near-vertical angle puts you over the bottom bracket for traction and a comfortable, sustainable climbing position.
  • Reach & stack — your actual riding position. We size by reach and match stack to it, so bar height stays consistent across sizes.
  • Chainstay length — rear-wheel traction and high-speed stability balanced against front-end agility.
  • BB height & drop — low enough for cornering stability, high enough to dodge pedal strikes; recalculated for mullet builds via flip chip.
  • RA Reach Adjust — a headset system that shifts the front axle ±5 mm without touching head angle.
The design ethos

Geometry isn't cosmetic. A degree of head angle changes how the front tracks at speed; a couple of millimetres of BB drop changes how often you clip a pedal. These follow physics, so we calculate every dimension before a tube is ever cut.

Every number is chosen for a reason — and the reason is always trail performance, never the spec sheet.

S-VOLVE S-VOLVESizing

Which size is really yours

S-Volve is our sizing — matching the frame to your body and the way you ride, not just your height off a chart. The goal is simple: put you on the size that's actually right for you, with room to fine-tune. Fit is what turns a great frame into your bike.

S-Volve — Sizing Evolution

What it governs
  • Sizing by reach — the most meaningful fit dimension, instead of guessing from standover and stature.
  • Rider proportions — size matched to how your body is actually built, not height alone.
  • Stack matched to reach — so bar height and front-end feel stay consistent whichever size you land on.
  • Reach Adjust headroom — ±5 mm within a size, covering riders between sizes and custom builds.
The design ethos

Fit drives confidence, and confidence drives control. The right size is the difference between riding the bike and fighting it — so sizing gets the same engineering attention as the frame itself.

S-Volve pairs with G-Volve: geometry defines the proportions of a frame, sizing decides which size fits which rider. Together they put you on a well-proportioned frame in the correct size.

The origin story

We found our motor on Mars.

  • Motor4.4 lb
  • Power90 Nm / 620 W
  • Battery400 Wh

The search for the best drive on earth led us somewhere off it. Maxon's precision motors run on the Mars rovers — engineered for a place with no service stops, no second chances, and zero tolerance for slop. We figured a motor trusted millions of miles from the nearest mechanic could handle your local trail. The Maxon Bike Drive Air is the reason why we started Dirte Bike.

That's not a spec sheet. That's where the journey started.

  • 4.4 lbmotor
  • 90 Nmtorque
  • 620 Wpeak power
  • 400%max assist
  • 400 / 600Wh battery
  • 85%efficiency
Explore the Maxon AIR S →

Precision is the point

Engineered in the lab. Proven in the dirt.

One frame. Earn the descent, or assist it.