Top Pick

WOOM 4

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A great, all-around bike. Rugged and nimble for moderate single-track riding, yet comfortable enough for street riding.

RATING: Exceptional

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

SEAT HEIGHT: 21.6" – 27.6"

WEIGHT: 17.5 lb.

GEARS: 8-speed

0

$449.00

Geared Bike

Yes

Rating

Exceptional

Weight

17.5 lb.

Seat Height

21.6" – 27.6"

Frame Material

Aluminum Alloy

Tire Size

20"

Geared Bike Type

Street/Trail

Brake Type

Dual Hand (No Coaster)

Suspension

None

Gears/Shifters

8/Grip

Gain Ratio

2.3/6.7

Wheelbase

835

Hand Brake Type

V-Pull

Available Colors

Red, Blue, Green, Purple, Yellow

Pros & Cons

PROS:
  • Low minimum seat height for a 20" bike allows kids to ride at a younger age
  • Wide range of gears (8-speed) suitable for long paved rides to basic trail riding
  • Low center-of-gravity geometry for easier balance and better maneuverability
  • Easy-to-use grip shifters
  • Variety of colors available
CONS:

Full Review

Buying your child’s first 20″ bike is akin to buying them their first car. Somewhere between reading about shifters, geometry, and gear-ratios, you think, “How did they get this old?” With gentle rides in the park gone for good, speed, power, and performance are now top on your list… as should be the WOOM 4.

6 year old riding purple WOOM 4 20" kid's bike. 7-year-old riding red WOOM 4.

A cream-of-the-crop all-around 20″ bike, the WOOM 4 is well-equipped to handle anything from long paved rides to mild dirt trails. With a lightweight frame and a low center-of-gravity for easy balancing and maneuvering, the WOOM 4 provides a comfortable transition for kids moving up from their 16″ bikes. And with 8-speeds for a wide range of gears and grip shifters for shifting newbies, the WOOM 4 is an excellent choice for kids who need a top-notch all-around bike.

Performance


While the WOOM 4 is great for riding around the neighborhood, is it soooo much more than your basic neighborhood bike.  We tested out the WOOM 4 with five different riders (aged 5 to 8) with various levels of ability and they all gave the WOOM 4 an enthusiastic thumbs up!

Our team of little testers demonstrated that the WOOM 4 excels on different terrains for many different types of riders. From young riders who are a little hesitant to move up to a 20″ bike,  to confident trail riders and aggressive riders ready to tackle every curb, jump or dirt mound they see, you really can’t go wrong with the WOOM. Its lightweight build (16.8 lb.), adjustable height handlebars (more about that below), and low center of gravity frame work together in unison to create a comfortable, confidence-building ride that kids love. About the only thing we wouldn’t recommend the WOOM 4 for is aggressive mountain bike riding!

WOOM 4 Works Great for Various Types of Riders

6 and 7 year olds riding WOOM 4 20" kid's bike down street, over curb, on gravel trail, and up unpaved hill.

Size

At 21.6″ the WOOM 4 has one of the lowest minimum seat heights for a 20″ bike. With the seat height maxing out at 27.6″, the WOOM 4 is generally a good fit for kids ages 5 to 8 (or kids 45″ to 51″ in height).

A child’s inseam, however, is truly king when fitting a bike.  In order to allow for proper leverage on the pedals, an experienced rider should only be able to touch the ground with their tippy toes while on the bike seat.  The seat height should, therefore, be set to 2″ to 3″ ABOVE their inseam to allow for proper leg extension while pedaling.  As a result, the WOOM 4 is ideal for experienced riders with an inseam ranging from 18″ to 24″ (regardless of age)

Our primary 6-year-old tester was just over 46.5″ tall with a 21″ inseam and was a great fit on the WOOM 4.  To ensure an accurate fit, we used WOOM’s height and growth chart, which compares your child’s height to the model of WOOM bike that best fits them.  A thick vinyl sticker that easily mounts to the wall, it removes any doubt as to which WOOM bike would be best for your child.

WOOM 4 Fit with 6-year-old

6 year old sitting on WOOM 4 with his tip toes on ground.

Frame & Geometry

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, narrower 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.   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.

Narrow Q-factor on WOOM 4

Rear view of child riding WOOM 4 and Novara 20" kids' bikes. WOOM 4 has a narrow q-factor allowing the child to push directly down on pedals. Novara has a typical and wider q-factor that forces kids to push down on the pedals at an angle.
Lower 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. Compared to low and mid-range 20″ bikes, the WOOM 4 has a much lower bottom bracket and shorter crank arms which provide more space for proper leg extension when pedaling.  In the picture below, you can see that WOOM 4’s pedals don’t come up as high on the upswing (in relation to the seat) as compared to the Novara bike.  This additional space provides for more distance between a child’s upper and lower leg, allowingt them to exert more force on the pedal.

Bottom Bracket Height and Proper Leg Extension on the WOOM 4WOOM4 bottom bracket height, proper leg extension on 20" kids bike. Lower bottom bracket and shorter crank arms mean more room for leg extension when pedaling.

Adjustable Handlebar Stem

New for their 2019 models, the WOOM 4 now offers an adjustable-height stem which allows parents to easily raise or lower the handlebars. 

How it Works

The stem (the black part that connects the white headset to the black handlebars) is comprised of two metal pieces that are shaped like number 8’s.  One side of the 8 is attached to the round portion of the headset while the other side is threaded through the handlebars.  Two Allen bolts hold the stem tightly around the handlebars and headset to keep everything securely together.

To adjust the height of the stem, the two bolts can easily be loosened, allowing the handlebars to be raised or lowered.  The handlebars also easily twist to ensure the brake lever and shifters are correctly positioned.

WOOM 4's adjustable height handlebars, showing how to loosen the two bolts to adjust the height, and min and max range of height adjustability.

What it Does

Raising and lowering the handlebars can significantly alter a child’s position on a bike.  Out of the box the handlebars are set to the middle position, which all of our testers preferred.  Not too leaned forward, but not too upright, 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.

Timid or beginning riders, however, may prefer the lowest stem height setting, which positions the rider in the most upright setting.  The more upright positioning is the result of the handlebars being shifted closer to the rider’s body.

Adventurous riders may prefer a more aggressive position, which can be created by setting the stem to its highest position. The highest position raises the handlebar by pushing the handlebars away from the child, which extends the child’s reach and creates a more aggressive body position. WOOM 4's handlebars at lowest stem setting put a child in the most upright position. The mid-range setting put a child in a mid-range position. The highest stem setting pushes the handlebars out and puts a child in the most leaned forward or aggressive setting.

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 aluminum fork offers some dampening but does not have a shock. While shocks can be extremely helpful for kids hitting the single-track or the pump track, for the majority of kids, it is more advantageous to skip the shock to help save on added weight.

In fact, most shocks on kids’ bikes are pretty worthless and act merely as eye candy. For those high-adventure kids looking for a front suspension bike, many big name bike brands have released lightweight 20″ bikes with front suspension such as the Prevelo Zulu Three.

Whether on paved or packed dirt trails, the WOOM 4’s 1.5″ wide Kenda Small Block Eight 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.

WOOM 4 Tires and Rims

WOOM 4's lightweight aluminum rims, Kenda 1.5" wide knobby tires, and white reflective strip on the tire.

Gearing and Shifting (Gain Ratio)

The WOOM 4 has 8 gears ranging from a 2.3 to a 6.7 gain ratio. With a wide range of gears, the WOOM 4 is ready to tackle hills as well as easily gain speed on flat rides. With one chainring in the back and a cassette of eight cogs in the rear, shifting is done via grip shift on the right hand. Twisting up shifts to a higher gear while twisting down shifts to a lower gear.

For riders just getting acquainted with gears on a bike, we’ve found grip shifters to be the easiest and most intuitive to use. For more advanced riders riding more aggressively on mountain bike trails, trigger shifters are generally better.

WOOM 4 SRAM Grip Shifters and Easy Reach Brake Levers

WOOM 4's SRAM grip shifter and short-reach brake lever.

Optional $20 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.

An optional kickstand on the WOOM 4 (only available on models sold after 2017), 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’s Optional KickstandKickstand on WOOM 4 is set farther back so as not to interfere with the pedals. Shown vs a traditional kickstand that interferes with the pedals.

Comparisons

The WOOM 4 is comparable to several other higher-end bikes, including the Prevelo Alpha Three and the geared Cleary Owl. While each bike has its specific strength, the WOOM 4 is our top pick for all-around riding.  The Prevelo Alpha has trigger shifters and a more aggressive body position best suited for ambitious riders.  The Clearly Owl is lightweight and positions the rider similarly to the WOOM, but it only has three speeds and its trigger shifting mechanism was trickier to learn to use for our testers as compared to the WOOM’s grip shifter.

Bottom Line

The WOOM 4 is the best all-around 20″ bike we’ve tested. Rugged and nimble enough for moderate single-track riding, yet comfortable enough for street riding, the WOOM 4 is the perfect, versatile bike to take your all-terrain rider anywhere they want to go.

 

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.

Disclosure: The majority of links provided are affiliate links we receive a small commission on sales made through them (including Amazon).
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