Prevelo Alpha Three Kids Bike Review (One Of The Best 20 Inch Bikes Around)

My son charges up the hill, pedaling out of the saddle, and maneuvers over a rooty section of trail. He cleans it, compliments himself, and powers on. My husband and I share a quick glance of disbelief — and pride.

I never would have imagined that a just-turned-5 year-old could climb like this, or that they’d be able to manage a 20″ bicycle with gears. But here we are.

When Jacob at Prevelo Bikes suggested that he thought my son was ready for the Prevelo Alpha Three, I was skeptical. It weighs quite a bit more than the Prevelo Alpha Two (the 16″ bike that my son was currently riding), and it has an eight-speed rear cassette.

I wasn’t convinced our little guy was ready for a bigger bike or gears, but I was game for giving it a shot. As it turns out, he figured out the shifting with 10 minutes of practicing, and any issues due to added weight have been negligible compared to the gains in his climbing ability with the addition of gears.

For parents interested in introducing gears at an early age, and for kids who have already mastered pedaling and bike handling, the Prevelo Alpha Three is the ideal 20 inch bike. It doesn’t have the front suspension of the Prevelo Zulu Three, but it provides big wheels, gears, and now hydraulic disc brakes for young kids who can’t yet fit on other 20″ bikes.

Oct 2025 Note: Prevelo recently released the new MKII version of the Alpha Three. While largely similar to the version we originally tested, there have been some noticeable improvements. I’ve updated the review to make note of these where relevant.

Review in a Nutshell

Pros:

• Low minimum seat height and standover height
• 8 speed Microshift Acolyte drivetrain with clutch derailleur
• Promax hydraulic disc brakes for excellent stopping power
• Beautiful aluminum frame
• Tubeless-ready wheels and tires
• Lightweight

Cons:

• Trigger shifters can be challenging for little hands
• Expensive (price has gone up from prior models)

Price: $759

Prevelo Alpha Three Video Review

Frame and Components

The frame, the wheels, and the rest of the component build are top-notch. Had we speced out a 20″ bike ourselves, we would have built it up just like this.

The naked aluminum frame looks good and is well-built. It has clean, solid welds, and doesn’t need paint to attract attention. (Although it does come in blue or pink if that’s your jam). The frame allows internally routed cables to keep things clean and tidy looking.

A new feature on the MkIII version is the built-in top tube mounting points for the Rider Supply Pod, Prevelo’s accessory bag. This is sort of a trendy thing on adult bike’s right now, and it’s fun that Prevelo has jumped on board.

Tires And Wheels

The Small Block Eight tires are miniature versions of the popular adult mountain bike tire (one of my faves) and provide a smooth fast-rolling ride experience. The 1.5″ tires are already plenty wide for tackling more challenging terrain, but the frame can also accommodate tires up to 2.1″ wide, giving you flexibility if you want something even beefier.

Both the tires and rims are tubeless ready which is something that really sets this bike apart. The closest competitor to the Alpha Three is the Woom Explore and it does NOT have tubeless compatible wheels.

Other nice-to-haves include a quick release seat collar and wheel skewers.  The quick-release seat collar allows for on-the-trail seat drops and easy adjustment of seat height as kids grow.  I also love finally having my son on a bike with quick release wheel skewers; this is a new experience as all his bikes up until this point have had bolt-on wheels.  The quick-release skewers allow for quick tire changes and easy installation.

Brakes

The Promax hydraulic disc brakes are a significant upgrade from the rim brakes we originally tested. They provide smooth, consistent, and reliable stopping power and are far more enjoyable for off-road riding compared to v-brakes.

The protected flat mount rear brake caliper is positioned snugly between the seat stay and chain stay, keeping it safe from trail hazards and accidental bumps. For young riders still developing coordination, hydraulic disc brakes mean more predictable, responsive stopping power across pavement, gravel, and light trails.

Gearing and Microshift Drivetrain

The bike comes with a 9-speed Microshift drivetrain. In our experience, the Microshift drivetrain is a game changer for bike companies. It’s affordable, comes with a short-cage derraileur, and is easy for kids to learn to shift with. It’s far better than the grip shifters that come stock on most kids bikes.

The cassette has a 11-36T range which gives kids plenty of gearing to work with. Compared to a singlespeed that your child is probably coming from, they will see a noticeable improvement in their ability to climb. On the other end of the spectrum, the top-end gears allow them to go fast on flat and downhill sections, which means that they’ll never be spun out again.

While I was concerned that, at 5, my little guy wouldn’t have the coordination and skill to understand when to shift up and shift down, my worry seems to have been for naught. He took to it immediately. This may not be the case for every 5 year old. I would certainly wait until a child has mastered other skills–pedaling, braking, cornering, etc–before adding a new dimension.

The Microshift Acolyte drivetrain provides clean shifting even for less-than-perfect-shifting kids. The clutch-style derailleur is a game-changer, helping to reduce frustrating chain drops over rough terrain.

Other Stuff Worth Noting

Other nice-to-haves include a quick release seat collar and wheel skewers. The quick-release seat collar allows for on-the-trail seat drops and easy adjustment of seat height as kids grow. I also love finally having my son on a bike with quick release wheel skewers; this is a new experience as all his bikes up until this point have had bolt-on wheels. The quick-release skewers allow for quick tire changes and easy installation.

Finally, it’s worth noting the custom-made crank arms. They are sized perfectly for young riders (110mm) and efficiently transfer power to the rear wheel.

Sizing

The Prevelo Alpha Three has a minimum seatpost height of 21.2″ and a low minimum standover height (16.5″). This makes it one of the smallest 20″ bikes around.

My son has a 19″ inseam and fits on the bike comfortably, although if your child isn’t already a comfortable pedaler I would wait until their inseam is closer to 20″.

For a 5 year old, the bike is going to be less nimble than a smaller frame. On his Prevelo Alpha Two for instance, my son is easily catching big air on the pump track and off of jumps, but struggles to get the Alpha Three up much at all.

There have been a couple of times that he’s had crashes and I know that it is simply because the bike is still a bit much for him to handle at times. That said, I’m still not sorry that we’ve introduced him to it, because the gear and bigger wheel size really do make a difference especially on the trail.

For a 6 year old, or kids already in a 6T pant, the frame is ideally sized with some room yet to grow.

Geometry

The geometry of the Prevelo Alpha Three hits a sweet spot.  It is aggressive enough to be ridden on serious trails, but upright enough to inspire confidence and maneuverability.  The long wheelbase provides stability, and the down-sloped top-tube allows young riders to easily mount and dismount. 

We appreciate that the bottom-bracket is low enough to provide a low center of gravity, but high enough that it can easily clear obstacles.  Lastly, the low-rise handlebars are wide and provide excellent control for young riders.

The only riders we wouldn’t necessarily recommend the Alpha Three for are kids just learning to pedal or particularly timid children.  They might be better off with a bike with slightly less-aggressive, more upright geometry.  (The Woom Go 4 is one example).

Weight

At 16.9 lbs, the current Prevelo Alpha Three is exceptionally lightweight compared to most 20″ kids bikes and is among the lightest geared 20 inch bikes available. This is also a significant improvement from the 19 lbs the older Alpha Three weighed, and makes it a great choice for more petite kiddos.

Comparison to the Prevelo Alpha Two and the Prevelo Zulu Three

Deciding whether the Alpha Two, Alpha Three, or Zulu Three is the best choice for your child is based on three basic factors: 1) inseam length, 2) ability level, and 3) preferred type of riding.

The most obvious (and important!) thing is your child’s inseam length. A bike that is too big (or small) for your child will result in a sub-optimal, and perhaps even dangerous riding experience.

As mentioned earlier, wait until your child has a 19″ inseam length before attempting to move up to the Alpha Three. The Zulu Three has a slightly larger minimum seat height and your child needs to have an inseam of at least 20″ to fit comfortably on it.

As for ability level, don’t push your child into a bigger bike or gears until they are truly ready. They should be riding confidently, quickly, and joyfully on a 16″ bike before attempting a 20″ bike. The bigger frame will also give them trouble if they haven’t yet developed good bike handling skills.

Finally, your child’s preferred type of riding should be taken into account. Assuming your child is large enough, the Zulu Three is going to be the preferable bike if your family does a lot of mountain biking.

The Zulu Three features an 80mm air suspension fork, making it a true mountain bike for kids ready to tackle more technical trails. However, all these features make the Zulu heavier—around 21 pounds. If, on the other hand, you are buying a bike for riding around town, on bike paths, and to school, stick with the Alpha Three. The Alpha Three is versatile enough to handle light trails and mixed terrain, but without the extra weight and cost of a dedicated mountain bike.

Bottom-Line

For smaller riders that are ready for gears, the Prevelo Alpha Three is the ideal 20″ bike. The lightweight aluminum frame, high quality components, hydraulic disc brakes, and 8-speed rear cassette will take your child to the next level in their riding ability. The MkIII version represents significant upgrades over previous models, with better braking, lighter weight, and improved durability—making it one of the most versatile and capable 20 inch bikes available.

Disclaimer:  Prevelo provided us with a bike to test for this review.  We were not paid nor did we receive any other kind of compensation, and all opinions are our own.  Some of the links in this review are affiliate links, meaning if you click thru and make a purchase, we receive a small commission.

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