The Ultimate Guide to Buying a Kids' Bike

Happy venturing down a gravel path, up a mountain road or on the MTB trail, the 20 in. woom OFF 4 kids' mountain bike can also hold its own on the pavement and is specifically designed for kids.
Imported.
| Best Use | Mountain Biking |
|---|---|
| Frame | 6061 T6 aluminum with butted and hydroformed tubes |
| Mountain Bike Style | Cross-country |
| Bike Suspension | No Suspension |
| Fork | Light carbon fork; 1 to 1-1/8 in. tapered steerer tube; 100 x 15 mm thru axle; post mount for disc brake |
| Crankset | Lightweight, forged aluminum, 4.3 in. (110 mm), kid-specific cranks with narrow tread (Q-factor); narrow-wide chainring with 28 teeth in the front |
| Bottom Bracket | Thun |
| Shifters | SRAM X5 trigger shifter |
| Rear Derailleur | SRAM X5 rear derailleur |
| Rear Cogs | Sunrace 9-speed 11-32T |
| Number of Gears | 9 gear(s) |
| Brake Type | Hydraulic Disc Brake |
| Brakes | Promax Hydraulic disc brakes |
| Brake Levers | Ergonomic brake levers designed for childrens' hands |
| Rims | Tubeless-compatible Alexrims wheelset |
| Front Hub | Front hub for disc brake, 20h, 14 gauge, 100 x 15 mm, 2x bearings without quick release |
| Rear Hub | Rear hub for disc brake, 20h, 14 gauge, 135 x 12 mm, alloy cassette body, 4x sealed bearings; without quick release |
| Wheel Size | 20 inches |
| Tires | Schwalbe Rocket Ron with ADDIX SPEED rubber compound 20 x 2.25 in. |
| Tire Width | 2.25 inches |
| Handlebar Shape | Riser Bar |
| Handlebar | Aluminum; sandblasted; silver anodized; width: 570 mm rise: 20 mm |
| Stem | Forged aluminum; CNC-machined; rise/drop: +/-15 deg. with flip-flop design to adjust the handlebar height; length: 50 mm |
| Seat Post | Anodized aluminum; 27.2 x 250 mm; insertion marks indicate the minimum insertion depth; quick-release seatpost clamp |
| Saddle | Mountain-bike specific saddle with side protection |
| Pedals | Fiber-reinforced nylon; flat; 2 x 6 pins; chromoly axle |
| Headset | Fully integrated 1 to 1-1/8 in. headset; sealed industrial bearings |
| Chain | KMC X9 NPGY 1/2 in. x 11/128 in. |
| Weight | 18 lbs. 8 oz. |
| Bike Weight | Bike weight is based on median size, as sold, or the average of two median sizes. |
| Gender | Kids' |
| 20 IN | |
|---|---|
| Height Range | 46 - 51 |
| Effective Top Tube | 18.1 |
| Head Tube Angle (degrees) | 68 |
| Seat Tube Angle (degrees) | 70 |
| Wheelbase | 33.5 |
All measurements are stated in inches unless otherwise indicated.
Adding a review will require a valid email for verification
The woom air is a fantastic first entry into mountain bike for a younger kid. This model doesn’t have suspension, so if your kid is already hucking off jumps you would probably want that model. But the amazing thing is you can always upgrade the fork! The build quality is fantastic. We had woom 1&2s and the thing we loved still holds true with this modem, it’s super lightweight which is key for a kid who is starting out with a bit of “hike a bike”. The kid wanted me to mention that the seat is comfy, and the shifting is easy, and he loves how lightweight it is. If you have a smaller child, this might not fit until they are 6+. Our son is 44” and he is on top toes as the lowest seat post, so any shorter and you’ll want to wait or look at the woom 3. Love the bike and happy it provides the ability to introduce my fomo son to MTB!!!
My son LOVES this bike. He started with riding with a guardian when he was 4, and he outgrew it very quickly. He could only go about 3-4 miles on it because of the weight and the fact that it was a single gear bike. With the Woom 4, he is able to ride 6-7 miles at least, and has a blast. The bike is extremely light weight, and having front and rear brakes, and a cassette in the rear makes a huge difference. This bike is definitely a step up. The bike is extremely well made - it looks and feels like a premium bike. It is geared towards mountain biking but it does not have a suspension. The bike came mostly assembled in the box, and the instructions to finish setting it up were extremely easy to follow. The tools needed to put it together are included with the bike. My only disappointment is that it is still too small to fit in my bike carrier. I have a Thule Apex XT 4-Bike Hitch Rack, and the bike does not fit on it.
… not for the price. For starters I needed to buy a kickstand separately. The purists will say “but it’s a mountain bike” … yeah, but it’s a kids bike! And for the price, provide the kickstand and let me decide whether to keep it on or not. Additionally, and this will vary from kid to kid … the shifters take a little getting used to, so it’s not really kid friendly from the start. And the gear ratios should include one higher gear. Otherwise solid color and good build.
We've had both the OFF and OFF AIR for our kids (Aged 4 -6) and been so impressed with how these bikes have allowed our kids to progress. With our youngest being on the small end of sizing, the lightweight OFF carbon fork allowed him to climb hills effortlessly, with bigger tires allowing him to comfortably navigate over roots, rocks and curbs. I've only heard him brag about how fast his bike is and how much he loves it.Our daughter has had a OFF AIR for two years and progressed way quicker than her peers. Both kids are ripping down XC bike trails, climbing hills without complaints and figured out the gears near instantly. The woom bikes OFF series are such quality rides, lightweight for the littles to feel energetic on, and just a huge boost to the confidence of riders that need to test unfamiliar terrain - allowing them to keep going and want to get on their bikes again, and again, and again.We've had 4 other high end MTB brands for our youngest, and woom was definitely the best value / quality.
Woom 4 off is a fantastic bicycle because it is lightweight and well suited to the pump track and mountain biking. My son has been biking so much since he received his woom 4 off that we can't get him off of it. Yesterday, we went to the pump track, we're about to leave after a few hours there, and he said "please wait papa, just 10 more times." He has been absolutely ripping it!! In comparison, my older son has a much heavier mountain bike, and he tends to watch (not riding) as much as he rides. Alas, he needs a Woom. As the kids grow up, I encourage Woom to make 27" or xs adult size mountain bikes that are extra lightweight yet provide suspension options, and to eventually expand into the adult market. I wish the Woom Off 4 was already tubeless, because my son doesn't like the trail bumps that much. It's the first upgrade we will make! My brother's friend heard news and has already purchased a woom bike for his child. Should you get one for your child? Yes. Then, sell it when it doesn't fit and get the upgrade!
This is an awesome kids bike , my 7 year old grand daughter loves it. I had the REI bike shop convert it to tubeless before it left the store. And the 18 lb. range makes it one of the lightest on the market, do a comparison and you see.
Its basically a very light mountain bike for a kid. Seems to be the lightest best bike for a young kid to develop skills.
This is our second Woom bike. We love it and will be coming back for the next size when our boy is ready!


Start earning an annual Co-op Member Reward* with a $30 lifetime membership!
10%
Earn $94 in rewards on this item
And earn 10% rewards on future eligible purchases*