Guardian 20″ Large, Single Speed – Original

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A comfortable and smooth ride, the Guardian's unique SureStop braking technology makes them truly stand out.

RATING: Exceptional

BEST FOR: Kids ages 5 to 8 in need of a durable and reliable bike for everyday use. The simplicity of single-speed bikes makes them ideal for the typical child rider who rides mainly around the neighborhood.

SEAT HEIGHT: 22.5" - 28.5"

WEIGHT: 19.5 lb.

GEARS: Single Speed

Geared Bike





19.5 lb.

Seat Height

22.5" – 28.5"

Frame Material

Aluminum Alloy

Tire Size


Brake Type


Gain Ratio


Handlebar Height




Hand Brake Type


Available Colors

Blue, Black, White

Pros & Cons

  • Patented SureStop braking system for faster and more controlled braking
  • Low center-of-gravity design for easier balancing and maneuverability
  • Great quality build for the price
  • Fun, kid-approved designs
  • Long wheelbase can be a stretch for kids with shorter torsos (20" Small frame is better)

Full Review

Over the years, kids’ bikes have made substantial improvements.  From lighter frames to more responsive brakes, kids’ bikes are finally beginning to get the much-needed upgrades they deserve. Guardian Bikes, a newer kid-specific bike company featured on Shark Tank, saw these improvements and then raised the bar up a notch.  Recognizing the need for not only more responsive brakes but for a safer braking system altogether, Guardian developed their patented SureStop braking system that continues to delight and impress parents and kids alike.

Child riding Guardian 20" geared bike.

Why a Guardian?

Guardian Bikes were designed and built with one goal in mind – make biking safer for kids by revolutionizing how kids stop a bike. While Guardian bikes have many great features such as lightweight frames and child-specific geometry, their proprietary SureStop braking system is their main selling point.  Unique to Guardian, the SureStop system allows riders to stop faster and with more control.

We’ve seen time and again that SureStop allows kids to feel more in control on their Guardian bike, and as a result, their confidence level increases.  With less anxiety about stopping the bike, many kids are more willing to ride more adventurously.  Over the years, we’ve witnessed timid and once hesitant riders learn to love biking as the result of the confidence the SureStop braking system provides them.

Having tested out SureStop brakes myself, I understand our testers’ perspective.   Braking with SureStop brakes provides a similar feeling to braking in a new car with an advanced braking system versus an older car with a standard braking system.  Not only is it easier to brake faster, you feel MUCH more in control of the car.  As a result, you’re a more confident driver in a car with advanced brakes, and driving is more fun as well.

How Does the SureStop System Work?

Guardian’s unique braking system allows the rear and then the front brake to be activated sequentially with the pull of ONE brake lever.  Once the lever is pulled, the back brake is activated.  Once the rear brake has engaged, the SureStop system on the rear brake pad then activates the front brake.  This sequential stopping system allows the bike to stop faster and with more control.

Guardian Bikes SureStop Braking Technology

Graphic showing three steps to Guardian's SureStop braking system. Step One: Child activates brake lever, Step Two: Rear Brake Engages, Step Three: Rear brake activates front brake.

Benefits of a Single Brake Lever

Dual-hand brakes work great for advanced riders and are essential for technical youth riders (such as mountain bikers), but can be confusing for the average child rider.  If they accidentally brake with just the front brake, the front tire can lock up, which causes the rear tire to come off the ground and potentially throw the child off the bike.  Sadly, we have seen this several times.  With ONE brake lever on the Guardian, a child cannot accidentally brake incorrectly.  They simply squeeze one brake lever and the SureStop takes care of the rest.

Six-year-old on Guardian 20″ Large Single-speedGuardian kids' bikes feature one, easy reach brake lever.

Guardian’s 20″ Bike Models: Original vs. Ethos Line

Guardian offers 5 different models of 20″ bikes.  Which 20″ bike is best for your child depends on their size as well as how they plan on using the bike. All 5 models feature the SureStop braking system but vary in size, gearing options, and quality level.  Guardian’s Original line is Guardian’s premium line and features higher-end components than their budget-friendly Ethos line.

Offering the same seat height ranges and basic designs, the Original and Ethos lines are like different models of the same car.  The two lines are very similar, but with a handful of differences that vary in importance according to how the bikes will be used.

Premium “Original” Line: Designed for those riding more aggressively, around hills, or for those who simply want the best components.  It has a lighter aluminum frame and an upgraded shifter that is easier to shift.

Budget “Ethos” Line: Comes with a price about $100 less than the “Original” and a slightly heavier steel frame, more basic graphics, and a standard grip shifter that takes more effort to shift than the upgraded version.

Does My Child Need a Large or Small?

In order to offer the best fit for your child, Guardian’s 20″ bikes come in two sizes – Small and Large. Guardian’s 20″ Large is similar in size to standard 20″ bikes, while the 20″ Small is a much needed in-between size between a standard 16″ and 20″ bike.  The 20″ Small is designed to ease the jump from a 16″ to a 20″ bike which is often challenging for timid or lightweight riders as well as younger riders who are tall for their age.

With tires that are 4″ larger than a 16″ bike, a frame that is several inches longer, and with a significant increase in weight, standard 20″ bikes are often too big for some riders who have outgrown their 16″ bikes.  While the tire size of the 20″ Small is the same as the Large, the wheelbase and the minimum seat height are both about 2″ shorter than the Guardian’s 20″ Large frame, thereby creating a smaller, more manageable bike.  As a result, Guardian recommends the 20″ Small for ages 5+ and the 20″ Large for ages 6+.

Guardian’s Virtual Bike Sizer

Confused about which size is best? While a child’s height is generally a good indicator of fit, Guardian has recently released a new avatar-based sizing guide to help you visualize and confidently determine which size bike frame is best for your child.  Their RideSizer technology will allow you to see how your child will grow on the bike and predicts how long before they outgrow the bike.

The recommended bike size comes is displayed right away, but their estimations are presented via a chart that is emailed to you (via Guardian). Based on our experience, it works great, but if you have a child with a long torso and shorter legs, be sure to check their inseams against the bike’s minimum seat height to ensure a great fit.  It’s a super cool tool, give it a try below right here on our site.

Single Speed or Geared Bikes

Unless a child really needs gears to travel long distances or over hills, we generally recommend buying a single-speed 20″ bike for kids aged 5 to 8.  In addition to being more complicated to use, geared bikes require somewhat regular maintenance, which can quickly add up in cost.

The main problem is that the derailleur (the component that changes the gears on the rear wheel) on essentially ALL 20″ geared bikes sits very low to the ground (this includes high-end brands as well).  As a result, they get beat up on a regular basis and can stop working.

The back wheel of a 20" single speed Guardian bike with no derailleur, and the back wheel of a 20" geared Guardian bike with a derailleur.Whether a child drops the bike down on the derailleur side of the bike, or if they simply take a tight turn, the sensitive mechanisms of the derailleur often need tuning or even replacing.  As a result, we recommend a single-speed bike for basic neighborhood riders, the Ethos 6-speed for those who want gears for fun, and the Original 6-speed for those who NEED gears.


Ideally, a bike should weigh less than 40% of a child’s weight, but that is often hard to achieve for kids. (For reference, most adults ride bikes that are no more than 20% of their weight!).  Compared to similarly priced bikes, Guardian Bikes are several pounds lighter.

Higher-end brands are lighter than Guardian, but don’t come with Guardian’s SureStop braking system, and do come with a higher price tag.  Guardian Bikes also weigh more than higher-end brands due to their double walled, high-spoke-count wheels.  Built to withstand anything kids can throw at them (even stairs!), Guardian’s durable wheels are sure to stay true.

Quality & Assembly

In addition to Guardian Bikes’ superior braking system, they’re built with quality components that will last for years to come.  Both lines of bikes come with a kickstand, while the Original also comes with an upgraded threadless headset, Shimano shifters, and an aluminum frame.  To ensure quality and ease of assembly, every Guardian bike is checked, tuned, and re-packaged by Guardian’s own mechanics in California BEFORE they are shipped out to customers.  Bikes are NEVER shipped straight from the factory to the consumer. Both bikes we received from Guardian were ridiculously easy to assemble, were put together in less than 15 minutes, and required no additional tuning once assembled.

Collage of features on Guardian bikes: threadless headset, Shimano Grip shifter with view window, kickstand, and quality, smooth welds.

Gearing and Brakes

The brake levers and braking system on the Ethos and Original are the same, but their shifters are different.  The Original has an upgraded Shimano shifter that is easier for kids to use.  The upgraded shifter is also narrower, making it easier for kids to wrap their hand around the grip shifter.  The narrower grip also places their hand closer to the handlebars, thereby making the brake lever easier to reach.

Guardian 20″ Large Original Upgraded Shimano Grip ShifterGuardian's Original line features an upgraded, narrower Shimano grip shifter that makes the brake lever easier to reach than on the budget Ethos line.

To offer you a lower price, the Ethos line does not have the upgraded Shimano shifter but a standard Shimano shifter that is commonly found on less-expensive bikes. It requires more effort to twist to shift and is also wider in diameter.  Being wider, kids often place their hands to the side of the grip shifter, versus over it.  As a result, their hands are farther away from the brake lever, making it harder to reach.

Based on our experience with various testers, kids with a hand length around 5″ or more had no problems reaching the brake lever. For the average rider who shifts more for fun than necessity, the Ethos shifter will likely work just fine, but for those who need to shift out of necessity, the upgraded Original is worth the additional expense. 

Guardian 20″ Large Ethos ShifterGrip shift knob on the Guardian Ethos line of bike is wider and forces kids to grip the lever at an angle.

Bottom Line

Safe, lightweight and fun to ride, Guardian’s line of bikes is simply amazing. Whether cruising the neighborhood or enjoying extended family bike rides, your child will be in good hands with a Guardian.


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.


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