Assault AirBike Pro X
A belt-driven 27-inch fan bike on 20 sealed bearings, with a 7-year frame warranty — the quiet version of the machine everyone knows.
Specs
| Frame | Heavy-duty steel |
|---|---|
| Fan | 27 in diameter steel |
| Drive train | Square-tapered, 2-stage belt drive |
| Bearings | 20 sealed cartridge bearings, one in every pivot |
| Pedals | Reinforced pedals and crank |
| Finish | Industrial powder coating |
| Max user weight | 330 lb |
| Assembled weight | 124 lb (56.3 kg) |
| Length | 50.95 in (129.41 cm) |
| Width | 23.34 in (59.28 cm) |
| Height | 50 in (127 cm) |
| Warranty | 7-year frame, 3-year moving parts |
These figures are copied from Assault Fitness’s own published specs and were last checked on 2026-08-31. Manufacturers revise products without notice, and variants differ. Confirm anything your decision depends on with Assault Fitness before you buy.
Choose this one if
- You want the Assault build with a belt instead of a chain
- You want the biggest fan here and the resistance ceiling that comes with it
- You want a seven-year frame warranty on a machine you intend to abuse
The detail
Twenty sealed cartridge bearings — one in every pivot — is the specification that separates this from a cheap fan bike. Every joint on an air bike is a wear point: the crank, the arms, the pedals, the seat post. Bushings in those pivots develop play, and play becomes the creak and wobble that makes an old air bike unpleasant. Sealed bearings do not, and sealed means chalk and sweat stay out.
The 27-inch fan is the largest here — the Fringe Raptor, Bells of Steel Blitz and Force USA AirBike all use 25-inch fans. Because air resistance scales with the square of fan speed, a bigger fan means more resistance at a given cadence: harder at the top end, and a higher ceiling for someone strong enough to find it.
Belt drive is what the "X" is for. The classic AssaultBike is chain-driven, and a two-stage belt removes the mechanical clatter, the stretching, and the lubrication. It also seals better against sweat and dust, which on a machine you will sweat directly onto is the difference between five years and ten.
Seven years on the frame and three on moving parts is the strongest warranty in this category by a wide margin — against two years on the Blitz and three on the Raptor.
At 124 lb it is heavy enough to stay put under a genuine sprint, which lighter bikes do not. The 330 lb user rating is slightly below the 350 elsewhere, which is worth checking if it matters to you.
Fifty-one by 23 inches of floor, permanently.