Guardian 16 Inch ETHOS and AIROS Bike Review

Scoring high in looks and performance, the Guardian ETHOS 16 and the AIROS 16 both offer fun designs that appeal to kids and safety innovations parents will love. With a semi-upright body position, no-coaster brake, as well as Guardian’s unique and innovative SureStop braking system, the Guardian’s 16 inch bikes are a great choice for both first-time pedal bike riders as well as experienced riders looking for a great quality bike for riding around the neighborhood.

In our review, we’ll cover why the SureStop braking system makes Guardian Bikes so unique, and how the AIROS (previously called Original) and ETHOS lines are different.

young boy riding a 16 inch boys pedal bike

Guardian 16 inch Overview

RATING: Exceptional (AIROS), Highly Recommended (ETHOS)


BEST FOR: Kids 4 to 6 who will be doing neighborhood and paved trail riding. SureStop braking system is ideal for timid riders who need the security of an easy braking system, as well as adventurous riders who need extra stopping power.

SEAT HEIGHT: 18.5″ – 23.5″

WEIGHT: 16 lb. (AIROS), 17.5 lb. (ETHOS)

BRAKES: Surestop Dual Hand


FRAME: Aluminum Alloy (Airos), Steel (Ethos)


  • Proprietary SureStop braking system for faster and more controlled braking, and NO coaster brake
  • Comfortable upright positioning for young riders
  • Handlebar height is adjustable for more a precise fit
  • Eye-catching design – fun, colorful graphics and colored rims


  • Upright design not ideal for aggressive riders

Guardian 16 Inch Video Review

Want to see the Guardian bikes and their proprietary SureStop braking system in action? Check out our view summary which details the main reasons why parents and kids love Guardian bikes! Please note that Guardian’s Airos line is referred to as “Original” in this video.

Guardian ETHOS 16 and AIROS 16 Put to the Test

“Can we PLEASE go ride bikes??”  There’s just something about Guardian bikes that kids love.  From their fun and exciting graphics to their unique SureStop braking system, it’s never a surprise when a Guardian bike becomes our tester’s bike of choice.

Following in the footsteps of its 20″ and 24″ big brothers, the Guardian 16 inch was a hit straight out of the gate and offers a smooth and comfortable ride, especially for beginning riders.  Built on a lightweight frame with a low center-of-gravity design and complemented with upright handlebars, the Guardian 16″ is easy to balance and easy to maneuver.

Guardian 16 Airos bike in action

Guardian’s SureStop braking system is what really makes these bikes shine.  Guardian’s system stops the bike using the power of two v-pull caliper brakes, like many high-end kids’ bikes. However, it simplifies the process for kids by allowing them to pull just ONE brake lever to activate both brakes.

With SureStop, the difficulties that can arise with coaster brakes, as well as dual-hand brakes, are both eliminated.  How does the SureStop system work?  Not to worry, we’ll cover the details later in the review.

Guardian Bikes 16 ETHOS vs. AIROS (Original) Line

Guardian bikes are available in two different quality tiers – the higher-end “Airos” line (previously called Original), and a more budget-friendly “Ethos” line.  The 16″ bikes from the two lines are the same size, come in almost identical designs, and both feature Guardian’s unique braking system (SureStop).

Where they differ is in components.  The Ethos line runs about $100 cheaper and is built with a steel frame versus an aluminum frame as well as a threaded headset versus the threadless headset on the Airos line.

Guardian 16 inch AIROS and ETHOS Bikes

Side by side comparison of 4 year old boy riding the Guardian 16 inch Ethos bike and Guardian 16 inch Airos bike down the sidewalk

In the image above, the simplified graphic design can be seen on the Ethos line on the right as compared to the Airos line shown on the left.  The steel tubing on the Ethos is also thinner than the aluminum tubing on the Airos.  Both bikes, however, feature a pop of color in the rims.

Guardian 16 inch AIROS Bikes

Boy and Girl on 16 inch Guardian kids' bikes - pink and blue

The lighter Guardian Airos is ideal for lightweight and timid kids (as well as those who simply want the best), while the Guardian Ethos is a great choice for those riders who can handle a slightly heavier bike as well as those on a tighter budget. Compared to similarly priced 16″ bikes, however, the Ethos is still pretty light as it is almost a pound lighter than the Raleigh MXR 16 and 1.5 lb. lighter than the Specialized Riprock.

Features16" Original16" Ethos
16" Airos16" Ethos
Seat Height18" - 23.5"18" - 23.5"
Weight16 lb.17.5 lb.
BrakesSureStop, no coasterSureStop, no coaster
DecalsUpgraded Heat Bonded GraphicsTraditional Water Transfer Graphics

Guardian’s Unique SureStop Braking System

Our favorite feature of all Guardian Bikes, no matter the size, is their proprietary SureStop braking system.  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.

Our 6-year-old testers on the 16″ Guardians both mentioned the brakes without being prompted.  They accelerated and then stopped over and over again because they thought the brakes were “fun”.

Having tested out SureStop brakes myself, their description of “fun” is understandable.   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 more confident while driving a car with advanced brakes.

In our experience, the same applies to kids using SureStop brakes.  With much of the anxiety of braking gone, many kids are more confident in their riding. This also applies to adventurous and aggressive riders who really appreciate the extra stopping power SureStop gives them.

How does the SureStop system work?

Guardian’s unique braking system allows both 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.

Activating Guardian’s Single Brake Lever

single brake lever on Guardian 16 inch kid's bike

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.  It also prevents kids from going over the handlebars when accidentally braking with just the front brake.

brake cables and pads on Guardian Bikes 16 inch bike

Coaster Brake Free

While many parents think coaster brakes are just a normal part of 16″ kids’ bikes, we absolutely love that Guardian’s 16″ bikes do not have a coaster brake (back-pedal brake).  Coaster brakes can be very confusing for kids new to pedal bikes.

When learning to balance a bike, both kids and adults naturally pedal backward when they lose their balance.  Upon doing so on a bike with a coaster brake, the brake is unexpectedly activated, which often causes kids to fall. This process can be very frustrating for young riders which can then delay their mastery of a pedal bike.

On a bike without a coaster brake, a child can naturally pedal backward without activating the brake. Once they regain their balance, they can continue to pedal forward without a break in the momentum they just gained on the bike.

What size child will fit on the Guardian 16 inch bike?

The seat height on both 16″ Guardians ranges from 18.5″ to 23.5″.  If the Guardian is a child’s first experience riding a pedal bike (without training wheels) they will need an inseam of at least 18.5″ to fit on the bike (usually kids’ in 4T pants).

First-time bike riders need to be able to place their entire foot on the ground while standing over the seat in order to comfortably start and stop the bike while they are learning to balance and use a handbrake.

For those kids who are already comfortable riding a pedal bike without training wheels, if they have an inseam of at least 16.5″ they can fit on a 16″ Guardian.  Experienced riders only need to be able to touch the ground with their tippy-toes as they are comfortable starting and stopping a bike without using both of their feet.

When choosing the right size Guardian bike, be aware the Guardian’s 20″ Small bike size can have some overlap with the 16″. Both our 42″ tall tester in the red shirt and our 47″ tall tester in the striped shirt below, loved the 16″ Guardian, but the 47″ child was a much better fit on Guardian’s 20″ Small.

Guardian ETHOS 20 Small and ETHOS 16

Boys sitting side by side on their Guardian bikes. 20" small in red and 16 inch in blue.

Keep in mind that both lines of Guardian 16″ bikes are also not compatible with training wheels, so kids under 40″ will not fit on the bike.

Guardian Bikes 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 displayed right away, but their estimations are presented via a chart that is emailed to you. 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!

Guardian 16 Geometry

Handlebars & Body Position

Guardian 16″ bikes are designed for beginning riders who often prefer an upright body position.  Sitting upright centers a child’s weight over their hips, just like they’re accustomed to when standing and walking. As a result, beginning riders are usually able to master balancing a bike faster when sitting upright.

Experienced riders, however, may prefer a bike with lower handlebars that place the rider in a more aggressive position.  A more aggressive position better allows the rider to shift their body weight during turns and while on hills.

Compared to other higher-end bikes, the Guardian 16″ is not as upright as the woom 3, but much more upright than the Cycle Kids 16″.

Body Position on Guardian ETHOS 16

Side by side comparison of three 16" bike, showing body position of rider. woom 3 is most upright and cyclekids is most aggressive. Guardian 16 inch is in the middle.

How much do the 16 inch Guardian Bikes weigh?

The aluminum-framed 16″ Airos weighs 16 lb. while the steel-framed Ethos weighs 17.5 lb.  Compared to similarly priced bikes, the Guardian models are slightly heavier, but not by much.

Much of their difference in weight is due to the rims and tires on the Guardian bikes.  To keep the tires properly aligned through kids various adventures, Guardian’s bikes come with a beefier rim than most 16″ bikes and have a lot more spokes as a result.  The additional spokes help keep the tire properly true, even when repeatedly going down jumps or curbs.

The 1.75″ wide tires on the Airos line’s also wider, and therefore heavier, than most bikes.  The Ethos’ tires, however, are the standard 1.5″ width found on most 16″ bikes.

In addition to providing slightly more cushioning and traction, Guardian has found that kids prefer the look of the wider tires.  Based on our experience, however, for the average everyday rider (not all-terrain riders), the width of a child’s tires makes very little difference in the bike’s performance.

Gain Ratio (How easy are they to pedal?)

The gain ratio on a single-speed bike is a number that represents that single gear, or how hard or easy it is to get started pedaling and maintain fast speeds.

The gain ratio on both 16″ Guardian bikes is mid-range at 3.55.  This makes the bike geared perfectly for cruising around the neighborhood.  As a comparison, the Cleary Hedgehog is designed for aggressive riding around hills and is geared at a low 2.88 while the Cycle Kids 16″ is geared high at 4.3 for faster riding on flat surfaces.

Guardian 16 inch Bike Review Bottom Line

Guardian’s combination of SureStop brakes, lightweight frames, and upright positioning make their 16″ line of bikes one of our top choices for 4 to 6-year-olds riding around the neighborhood and paved bike trails.  The Airos line is an exceptional bike offering upgraded graphics, sleek aluminum tubing, and a lightweight build, while the Ethos line provided top-notch performance for its price.

Both bikes lines are a best fit for kids with at least an 18″ inseam (for those riding a pedal bike for the first 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.

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