woom 4 Bike Review

Whether your child is a casual neighborhood rider or an aggressive speedster, the woom 4 offers the perfect blend of comfort, reliability, and agility. Its low center of gravity and adjustable design make transitioning from a 16″ bike easy, with plenty of room for growth.

Equipped with 7 gears, responsive dual hand brakes, and all-terrain tires, the woom 4 is ready for endless adventures. The woom 4 also comes equipped with a ridiculously easy-to-use kickstand to help keep the bike off the ground and protected from dings.

In this review, we’ll cover everything you need to know about the woom 4, including how it compares to the higher-end EXPLORE line.

woom 4 Overview

RATING: Exceptional

MSRP: $599

BEST FOR: Beginning to intermediate riders on a wide range of terrains and distances – from longer paved trails to basic single-track.

SPECIFICATIONS

SEAT HEIGHT: 22.1″ – 28″
WHEEL SIZE: 20″
WEIGHT: 16.9 lb.
GEARS/SHIFTERS: 7-speed/Microshift Grip
GAIN RATIO: 2.3/5.9
WHEELBASE: 825mm

View on woom

woom 4 Bike Review – Results of our Test Rides

Over the last four years, we’ve tested the woom 4 with over ten different kids (ages 5 to 8) with various levels of ability and they all gave the woom 4 two enthusiastic thumbs up!

What type of rider is the woom 4 best for?

Transitioning from a 16″ to a 20″ bike can feel like a big leap! Somewhere between shifters, geometry, and gear ratios, you’ll find yourself thinking, “How did they get this old?”

Thankfully, the woom 4 makes this step effortless. Whether it’s for leisurely rides to the playground or longer commutes to school, the woom 4 handles both with ease as it is so much more than your basic neighborhood bike.

Built with a lightweight frame with child-specifc components, the woom 4 is the perfect bike for a wide range of riders, from timid riders still unsure about biking, to confident riders needing an efficient bike for extended rides.

If gravel roads or basic compact dirt trails are nearby, the woom 4’s gearing, powerful brakes and all-terrain tires make it up for the task. While certainly not a mountain bike or a bike designed for super aggressive riders wanting to take on jumps and learn new tricks, the woom 4 is our favorite bike for the beginning to average 5 to 8 year old rider.

For those confident riders ready to tackle every obstacle in their path (or even create their own), the woom EXPLORE might be a better fit.

woom 4 ORIGINAL vs. woom 4 EXPLORE

The woom ‘s new EXPLORE line is designed for more adventurous and aggressive riders. If your child will be reguarly riding on gravel or dirt roads and could benefit from extra cushioning in the tires, or needs extra stopping power while riding up and down steeper hills, the EXPLORE is built for them.

While both bikes share the same frame, the EXPLORE model comes with hydraulic disc brakes, an upgraded, easier-to-use Shimano grip shifter and wider, more cushioning all-terrain tires. Additionally, the EXPLORE features black components and a matte paint finish, giving it a more mature and sleek appearance.

In our head-to-head tests, our riders preferred the EXPLORE, mainly for its shifter and color scheme. However, unless your child needs the enhanced braking power of hydraulic disc brakes (especially useful in wet conditions) or may struggle with the finer motor skills required to operate the ORIGINAL’s Microshift shifter, the extra cost of the EXPLORE may not be worth the additional expense.

What size child fits on the woom 4?

At 22.1″ the woom 4 has one of the lowest minimum seat heights for a 20″ bike. With the seat height maxing out at 28″, the woom 4 is generally a good fit for kids ages 5 to 8 (or kids 45″ to 51″ in height).  Shorter kids under 45″ are usually a better fit on the 16 inch woom 3, while the 24 inch woom 5 provides more room for growth for kids taller than 49″.

A child’s inseam, however, is truly king when it comes to making sure you’re buying the right size bike.  In order to allow for proper leverage on the pedals, an experienced rider should only be able to touch the ground with their tip toes while sitting on the bike’s seat. 

The seat height should be set to 2″ to 3″ ABOVE their inseam to allow for ideal leg extension while pedaling.  As a result, the woom 4 is best for experienced riders with an inseam ranging from 19″ to 26″ (regardless of age).

To give you an idea of how your rider might fit on the woom 4, we’ll show you riders on the low, high, and mid-range of that inseam range. Looking through these images you’ll see how the woom’s unique design allows kids on the very low and very high range to still comfortably ride the bike. The woom 4 has a much wider “good fit” range than most bikes.

Small Riders

Here is our very tall youngest tester, not yet 5-years-old. Her inseam is 19.5″ and she is 44″ tall with shoes on. Because she is a confident, advanced rider, she can get away with the 22.1″ minimum seat height being almost 3″ taller than her inseam. (When sitting on the saddle she can touch the ground with high tiptoes.)

If your child is this size and is currently riding a woom 3, they could certainly continue to comfortably ride that smaller bike for several more months, or until they are about 45″ tall. This is especially true for timid riders who may find the transition to a larger bike more intimidating.

Mid-Range Riders

Our primary 6-year-old tester is just over 46.5″ tall with a 21″ inseam and was an ideal fit on the woom 4. 

Older, Taller Riders

And lastly, our 9-year-old tester who is 52″ tall. With the saddle set to its max at 28″, she’s about to grow out of the woom 4, but can still happily ride it.

Adjustable Handlebar Stem – Better Fit as Kids Grow

So how is the woom 4 able to fit such a wide range of kids so well? One of the main reasons is its adjustable handlebar stem, which is unique for a threadless headset. The stem allows parents to easily raise the height of the handlebars on the bike almost 2″ as the child grows in height. How low or high the handlebars are set can also just be a personal preference of the rider.

What the Adjustable Stem Does

The handlebars rotate on an axis, so adjusting them affects both their height and reach. Raising the handlebars also pushes them farther away from a child – great for taller kids. Lowering the handlebars also brings them closer to the child – great for shorter kids.

Handlebars in Low vs High Position

Younger, Shorter Riders

Here you can see how the position of the handlebars affects the position of a child’s body on the bike. Our first little rider is 43.5″ tall, but with a 19″ inseam is the shortest rider that can safely and comfortably ride the woom 4. The seat is set to its lowest height (22.1″).

With the handlebars lowered and rotated closest to the her (left image), she can sit naturally without stretching out too much to reach the handlebars.

Short Rider – Handlebars in Low vs. Raised Position

Older, Taller Riders

On the tall end, raising the handlebars and extending the reach will extend the “comfortable fit” life of the bike. Raising the handlebars accommodates a taller rider’s longer torso, while pushing the handlebars away will prevent the child from being too cramped in the cockpit.

Here is our 52″ tall test rider who is about to grow out of the woom 4 and is ready for a woom 5. With the seat set to its maximum, the low handlebars (image on the left) make her look too big for the bike. By raising the handlebars (image on the right) her slight change in body position looks more relaxed and natural.

Tall Rider – Handlebars in Low vs. Raised Position

Riders in the Middle

What about somewhere in the middle? The middle position is upright enough to allow the majority of a child’s weight to rest on the saddle (kids naturally prefer to have their weight centered on their hips), while leaned forward enough to allow the rider to shift their weight through turns and while tackling hills. If you’re unsure where to start, begin somewhere in the middle and adjust from there based on your child’s feedback.

Frame & Geometry of the woom 4

Designed specifically for kids (not just “small adults”), the woom 4 frame is built narrower and shorter than the average 20″ bike. To properly fit under a child’s body, woom frames are built with smaller components to prevent kids from having to splay their legs out while pedaling.

Differences in Q-factor

The “width” of the bike (the distance between the inside of the pedals) is known as the q-factor in the bike world. The q-factor width is equal to the distance kids must spread their feet to pedal.

A bike with a lower q-factor provides more efficient pedaling as kids are able to focus more of their physical effort on pushing directly down on the pedal versus down and to the side.   As shown below with our 6-year-old tester, the woom 4 is narrower than typical 20″ bikes, making it more efficient and easier to pedal.

Low Bottom Bracket

Where the pedals are attached to the frame of the bike also plays a significant role in a child’s ability to balance and maneuver a bike. Pedals are attached to crank arms, which are attached to the bottom bracket of the bike frame. The lower the bottom bracket of a bike, the lower a child can sit in relation to the bike tires, and the lower the overall center-of-gravity of the bike will be.

The lower bottom bracket also creates more distance between the seat and the pedals, which provides more space for kids to properly extend their legs and to get more power out of every pedal stroke.

This is especially important when kids are riding a bike at its lowest seat height. While the woom 4 is vastly superior to cheap bikes you’ll find at Walmart, it’s even a standout amongst some of its higher-end 20 inch bike peers.

Here you can see the woom 4 and the Cleary Owl 20″ bikes set to 22″ seat height. At the highest point of the pedal stroke, the more relaxed knee bend angle of the woom 4 makes it easier for a child to push down on the pedal.

woom 4’s Components

Front Fork and Tires

In addition to being a lightweight and nimble bike, the woom 4’s tires and fork help it excel in various riding conditions. The rigid aluminum fork helps to significantly keep the weight down on the bike without affecting performance. While front suspension can be extremely helpful for kids hitting the single-track, for the majority of kids, it is more advantageous to skip the “cool shock” to help save on added weight.

In fact, most suspension forks on kids’ bikes are pretty worthless and act merely as eye candy. But for those high-adventure kids looking for a front suspension bike for true mountain biking, the woom 4 OFF AIR is an exceptional option.

Whether on paved or packed dirt trails, the woom 4’s 1.4″ wide Schwalbe Little Joe tires help provide plenty of traction for dirt, yet are thin enough to prevent a significant increase in rolling resistance caused by thicker tires. 

Wrapped around woom’s super lightweight Soopa-Doopa-Hoops aluminum rims, the woom 4’s wheels are well-prepared for a variety of surfaces.  For added visibility bonus, each tire also has a white reflective strip.

Grips, Gearing and Shifting (Gain Ratio)

The latest woom 4 model features ergonomic grips that reduce wrist strain, a seemingly small detail that can make a significant difference in rider comfort, especially on longer rides.

With seven gears and a gain ratio range of 2.3 to 5.9, the woom 4 is built to handle both hills and flat terrain with ease. Its simple single-chainring setup at the front and a 7-cog cassette at the rear allow for smooth shifting via a grip shifter on the right handlebar.

For kids new to using gears, we’ve found grip shifters to be the most intuitive. However, for more experienced and aggressive riders tackling mountain trails, trigger shifters—like those found on the woom OFF AIR 4—offer better performance.

In Fall of 2022, the woom 4 transitioned from an 8-speed SRAM SX4 system to a 7-speed Microshift system. The switch was primarily due to lingering supply chain issues from COVID. In fact, we have seen many of our favorite brands switch to Microshift in the last year. (Prevelo, Guardian, and Specialized kids bikes also use Microshift now.)

While the Microshift system is slightly more challenging for younger riders compared to the previous SRAM shifter, it’s still manageable with practice. Our main tester found shifting into 1st gear particularly difficult, though the need for such a low gear is rare. To compensate, she had no complaints or issues relying on the bike’s second lowest gear, effectively limiting the gain ratio to 2.7 to 5.9.

The Shimano shifter on the new EXPLORE 4 bike, however, is easier to use than the Microshift shifter on the woom 4. As a result, if your young rider doesn’t have a strong grip AND needs to shift into a low gear reguarly (if you live near hills), it may be worth considering opting into the EXPLORE line.

Narrow-Wide Chainring

For fewer hassles with the chain, the woom 4 also features a narrow-wide chainring to minimize chain slippage. Narrow-wide chainrings alternate the size of the teeth on the ring to match the narrow and then wide links on the chain. This helps keep the chain smoothly rolling along without skipping or missing a link.

More details about the benefits of narrow-wide chainrings are available on the drivetrain portion of our woom 5 review.

Kickstand

Kickstands can be lifesavers for kids’ bikes, but they can also be a pain.  The vast majority of kickstands are mounted right behind the crank arms of the bike.  As a result, if kids don’t remember to put up the kickstand before they pedal, the crank arm of the bike will get jammed in the kickstand.

woom 4’s included kickstand is unique in that it mounts on the rear of the bike, away from the crank arms.  As a result, if a child forgets to put up the kickstand, they can still pedal their bike without a problem.  The kickstand will then bounce up and out of the way whenever it comes into contact with the sidewalk, grass, or anything in its path.

woom 4 Review Bottom Line

The woom 4 is the best all-around 20″ bike we’ve tested. Fun, fast, efficient and comfortable, the woom 4 is perfect bike for a wide range of riders, including timid riders and commuters. We especially appreciate woom’s unique handlebar design that allows the woom 4 to be a good fit for a longer period of time.

FTC Disclosure: Affiliate links are included in this review.  No monetary compensation was provided for this review, however, the reviewed product was supplied by the manufacturer or distributor to help facilitate this review. All opinions and images are that of Two Wheeling Tots LLC.  All content and images are copyrighted and should not be used or replicated in any way. View our Terms of Use.