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woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
woom 4
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Bike  20" • 16.76 lbs
Child  6 - 9 years • 45"-51"
$ 449.00
ships same or next business day

The intro to gears!

The woom 4 is a dynamic bicycle that introduces children to gears!  Our SRAM X4 8-gear shifter expands the possibilities for the rider.  Whether they are out adventuring in an area with hills or going on a long commute in town, this 20" bike is as powerful as the growing child demands it to be.

  • Hassle-Free Assembly: Our Austin, TX based team of qualified mechanics prepare and quality check each bike prior to shipment. All tools and easy-to-follow in-home assembly instructions are included
  • The 20” woom 4 takes bike riding to the next level. Bike weight: 16.46 lb; Designed for ages 6 to 9 years or overall height 45"-51”. 
  • Bike: This all-terrain bike introduces kids to gears. With 8 gears and light Kenda off-road tires, it is perfect for exploring and longer rides
  • Shifting gears: The SRAM X4 8-speed shifters boost the joy of riding and expand the rider's range. The gear ratio is designed to handle any terrain, from steep climbs to long descents
Size: 20"
Weight: 16.76 lbs
Age: 6 - 9 years
Height: 45" - 51"
Available variants:
Red / Blue / Green / Purple
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Highlights at a glance
These are the most important features for children at this age:
Woom 3
All components that are specifically designed with safety in mind have the kidsafe PLUS seal. Click the icons to find out more.

Riding a bike is more than just fun in exercising. Discovering the world means expanding one's horizon.

Christian Bezdeka
Founder of woom

Bike geometry

  • A Wheel / Tire size 20"
  • B Cockpit / Grip height 29.33
  • C Steering angle 68°
  • D Horizontal toptube length 16.93"
  • E Wheelbase 32.48"
  • F Seattube angle 71.5°
  • G Minimum Seat Height 21.65"
  • H Maximum Seat Height 27.56"
  • I Crank length 4.33"


  • Frame Material: Light and high quality A-6061 Aluminum
  • 20" wheel size providing agile yet good natured riding characteristics: low step in height, very low minimum seating position, long wheelbase, very forgiving geometry Set up provides maximum stability, and excellent balance resulting in increased satisfaction
  • Continuous seat post design allows for maximum saddle height adjustment
  • light unicrown fork made out of aluminum
  • 1" shaft - designed for ease of steering
  • semi-integrated 1" headset = sealed ahead set made out of steel and aluminum
  • integrated ahead clamp
  • Forged Aluminum - 40mm, +/- 10°
  • no protruding screws in this fully integrated and proprietary clamp design, we call it the knee-friendly design
  • the handlebar is connected with two 6mm bolts
  • wide, ergonomic, and light aluminum handlebar for more control
  • sand blasted and black anodised
  • reduced diameter for extra small hands
  • free of softeners and pollutants
  • grippy diamond structure
  • handle bar ends contain rubber plugs for additional cushioning and safety
  • Light forged aluminum cranks with 110mm length and low Q-Factor
    (low width between both legs)
  • Beginner ratio: 28T front and 11-32 rear
  • plastic pedals
  • molded cartridge chamber
  • Easy to operate V Hand brakes
  • Two independent hand brakes (No Coaster Brake)
  • Mini V-Brake with levers suitable for small hands
  • brake lever with reach adjustability and ergonomic fit for very small hands
  • high quality Jagwire bowden cable for low friction and ease of operation
  • 1x8 gears
  • SRAM X4 twister shifter for ease of shifting
  • SRAM derailleur with short cage
  • Super light Soopa-Doopa-Hoops Aluminum rims
  • small Aluminum hubs for extended leg room at the rear wheel
  • sealed bearing hubs
  • wheel can be installed and removed with 5mm allen wrench
  • 20 Niro spokes 1.8 straight spokes
  • Kenda Small Block 1.5" x 20 light weight low profile balloon tires offer great damping, rolling performance and a lot of grip
  • Schrader valves (car valves) to inflate easily
  • Age specific and ergonomically designed and molded
  • Free of pollutant and toxins
  • side safeguard to lean against wall
Seat Post
  • Anodized aluminum seat post
  • integrated maximum insertion indicator
Seat Post Clamp
  • Aluminum quick release seat clamp with long lever for ease of use and operation
  • clamp is safely secured against unnecessary movements
Enclosed Tools
1 long allen wrench for headset, 15 wrench for pedals
16.76 lbs
Red, Blue, Green, and Purple
Shipping Dimensions
39.5" x 8" x 22"
Bike Information
Max wieght: 154 lbs (70 kg). At woombikes USA, we reserve the right to make changes to the information on our website at any time. Weights are based on time of information publication and are up-to-date. Weights may vary slightly, as we are always improving our bikes.

This is how we deliver your bike:
5 min., ready, go!


woom bikes grow with you

(optional purchase)

Kids grow quickly. Size and fit is important. Avoid making compromises and choose the right size bike for your child. This unique program is available to all of our customers and will allow you to size up to the next bigger bike as your child grows.

  • 40% back of the original purchase price.
  • We will reimburse 40% of the original bike purchase price when you order a new woom bike within 24 months.
  • Your old woom bike must be less than 2 years old and in rideable condition. Rideable condition means that you allow your child to ride the bike.
  • We manage the return shipping of your old bike. We will provide you with a prepaid return label.

Customer Reviews

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das Superleichte
free shipping
We offer nationwide free shipping and free 30-day return shipping.
das Durchdachte
fast delivery
We ship UPS Ground and your woom Bike will typically arrive in 3-5 business days.
das Passende
30-day satisfaction guarantee
We offer free 30-day return shipping for all of our products
easy assembly
Your woom bike arrives nearly entirely assembled by a pro!
garantierte Qualität
amazing service
full customer satisfaction is guaranteed
conscious products
We believe in creating bikes in an environmentally friendly manner