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OFF 4 20in Mountain Bike - Kids'
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Gravel paths, dirt roads, and real MTB trails. The woom OFF 4 is built to handle all of it
What Our Gearhead® Experts Are Saying:
"For kids aged 6 to 8 who are actually riding trails, this is the right tool. The carbon fork keeps the weight down where it matters most, the Rocket Ron tires have real grip and real volume for absorbing trail chatter, and the hydraulic disc brakes stop A light carbon fork, 9-speed SRAM drivetrain, and hydraulic disc brakes on a 20" kids' mountain bike. That is what the OFF 4 brings for riders aged 6 to 8 who are ready for actual trails. The Schwalbe Rocket Ron 20 x 2.25" tires with ADDIX SPEED compound deliver low rolling resistance on hardpack and real grip when the trail gets loose. Promax hydraulic disc brakes with 140mm rotors front and rear stop confidently without demanding serious grip strength. Nine speeds through SRAM X5 give enough range for climbs and descents, and the flip-flop stem adjusts handlebar height in two positions without additional hardware. Tubeless-compatible rims and thru axles round out the build.
Heads up - We do our best to keep bike specs and images current, but occasional component changes can happen without warning-and sometimes the photos might not show the exact build you'll receive. If you want to double-check the details, our Gearheads are always here to help.
Details
- Carbon fork keeps the front end light where it matters most for kids aged 6 to 8 on trails
- Schwalbe Rocket Ron tires in 20 x 2.25" grip loose terrain and absorb trail chatter
- Hydraulic disc brakes stop reliably in all conditions without heavy hand strength
- Nine speeds with an 11-32T cassette cover climbs, descents, and everything between
- Flip-flop stem adjusts handlebar height in two positions without extra parts
- Tubeless-compatible rims are ready to run without tubes when the rider is ready
- Thru axles front and rear add torsional stiffness for more responsive trail handling
- Cannot be upgraded to a suspension fork later — consider the OFF AIR if suspension matters
- Item #WOO000J
- Frame Material
- 6061 T6 aluminum
- Suspension
- hardtail
- Fork
- woom carbon
- Headset
- integrated 1 1/8 - 1in
- Shifters
- SRAM X5 trigger
- Rear Derailleur
- SRAM X5
- Crankset
- forged aluminum
- Chainring Sizes
- 28t
- Crank Arm Length
- 110mm
- Cassette Range
- 11 - 32t
- Brakeset
- Promax
- Brake Type
- hydraulic disc
- Rotors
- 140mm
- Handlebar
- lightweight aluminum
- Handlebar Width
- 570mm
- Grips
- silicone lock-on
- Stem
- forged aluminum
- Stem Length
- 50mm
- Saddle
- ergonomic
- Seatpost
- aluminum
- Wheelset
- Alexrims
- Hubs
- aluminum
- Front Axle
- 15 x 100mm thru
- Rear Axle
- 12 x 135mm thru
- Tires
- Schwalbe Rocket Ron, ADDIX SPEED
- Tire Size
- 20 x 2.25in
- Pedals
- platform
- Claimed Weight
- 17.9lb (8.1kg)
- Activity
- trail
- Manufacturer Warranty
- 2 years
Built For Real Terrain Riding
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Built For Confident Riding
Lightweight Trail Frame
A lightweight aluminum frame keeps handling responsive and durable for confident riding on trails
Disc Brakes
Powerful disc brakes with adjustable levers provide consistent stopping power and control in mud, dirt, and wet conditions
9-Speed Drivetrain
A wide-range 9-speed drivetrain delivers smooth, precise shifting and reliable pedaling across climbs and descents
Grippy Trail Tires
Tubeless-ready tires balance low rolling resistance with strong grip for confident riding on loose and uneven terrain
Trail-Tuned Geometry
A low center of gravity and longer wheelbase improve balance and stability on uneven terrain
Choose Your Ride
OFF Carbon Fork — Smooth Trails
A lightweight carbon fork keeps the bike efficient and responsive while reducing vibration on smoother trails
OFF AIR Suspension Fork — Rough Terrain
An adjustable suspension fork absorbs bumps and improves traction for more control on rough terrain
Find The Right Size
Geometry Chart
Size Chart
Complete Your Setup
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Made To Grow With Every Ride
woom started in a Vienna garage when two bike‑obsessed dads reimagined kids’ bikes from the ground up, engineering superlight, child‑specific designs that turned first wobbles into real, joyful riding. Today their award‑winning lineup evolves with kids, moving from tiny first bikes to more advanced models that keep pace as skills, confidence, and ride ambitions grow.