Size Guide

Prevelo Bike Sizing

Getting your kids the right size bike is important and, fortunately, also easy. You just need two pieces of information about your little rider:

  • Inseam
  • Rider Experience

Measuring Inseam

  1. Have the rider stand against a wall, hold a book between their legs so that it is firmly against their crotch (the same place their bicycle seat will be).
  2. Measure the distance from the floor to the top of the book.

Rider Experience

Children who are learning are more sensitive to bicycle height than children who already know how to ride a bike. For this reason, our recommendations for bicycle sizing vary slightly based on the experience lever of the rider. The chart below takes into account the fact that experienced riders tend to adapt better to a bike that is slightly larger. For this purpose we categorize young riders as either "Learners" or "Pedalers"

  • Learner: riders who either have not yet learned to ride a pedal bike, or are still frequently putting their feet on the ground while riding.
  • Pedaler: riders who can ride confidently and only put their feet down to stop.
Model Wheel
Approx. Rider Age
Learner Inseam
Pedaler Inseam
Alpha Zero 12" 1½ + 12.5 to 16.5
Alpha One 14" 3 to 5 13.5 to 16.5 13 to 16.5
Alpha Two 16" 4 to 6 16.5 to 22
15 to 22 
Alpha Three 20" 5 to 9 20 to 23 17.5 to 23
Alpha Four 24" 7 to 11 24.5 to 28 23 to 28
Zulu Three 20" 5½ to 9 22 to 26 20 to 25
Zulu Four 24" 8 to 11 25 to 29 23 to 29
Speed Silver
Power Purple
Braap Blue

Speed Silver: Ships in 5 to 7 Business Days
Power Purple: Expected to ship Late Oct
Braap Blue: Ships in 5 to 7 Business Days

Wheel Size
24 inches

Approx. Age Range
7 to 11 years


Easy Shifting
RAPIDFIRE+ shifter &
Smart Cage Derailleur

$15 Shipping
in the Continental USA

Shipping Terms

Checked and Tuned
Each bike is checked & tuned prior to shipment.

Easy Assembly
Includes all the tools you need & easy instructions.

1% for the Planet
Prevelo donates 1% of sales to planet worthy causes.

The 24" Alpha Four offers an 8-speed Shimano drive train. The 11-34T wide range gearing is the real deal and gives growing riders truly usable gear range. It features:
  1. Prevelo confidence inspiring low and narrow geometry. Prevelo geometry keeps the rider low, balanced and in control.
  2. Lightweight 6061 aluminum frame with custom formed tubing.
  3. Lightweight aluminum alloy fork with chromoly steerer.
  4. Tektro front and rear v-brakes.
  5. Quick release front and rear wheels for toolless wheel removal.
  6. Three piece crank with squared taper bottom cartridge bearing bottom bracket and ultra narrow Q factor.
  7. Custom made cranks. All Prevelo cranks are sized specifically for each model bike, down to the millimeter.
  8. Shimano ALTUS 8-speed drivetrain. This 8-speed derailleur has a SHIMANO Smart cage. This unique pulley cage permits the use of a shorter pulley cage without comprising gear ratio width. Because kids’ bikes have small wheel diameters, rear derailleurs on kids bikes hang low and close to the ground. The Prevelo Alpha bikes use Smart cage derailleurs to keep things high and away from the ground.
  9. Shimano ACERA RAPIDFIRE Plus Shift Lever. Small hands have a hard time using twist shifters. We use reliable silky smooth thumb shifters. They are easy for small hands to operate, have an indicator display, and operate just like shifters on high performance bikes.
  10. Replaceable derailleur hanger. If the derailleur takes a hard hit, the hanger can be replaced without repair to the frame.
  11. 11-34T wide span gearing gives riders plenty of range to spin up tough hills.
  12. 95% assembled. Just install the handlebar, seatpost, front wheel and pedals.


What the bicycle media is saying

two wheeling tots logo

The perfect mix of road warrior and basic all-terrain cruiser, the Alpha Four is built with kid-specific geometry for a precise, comfortable fit.

The Prevelo Alpha series is an exceptional line of bikes for eager young riders. Lightweight with a low-center-of-gravity, the Alphas are fun and easy to ride.


Kid Centric Features

kids sized bicycle crank

Kid Engineered Crank

prevelo alpha four kids bike gears

8 Speed Shimano Drivetrain with Wide Span Gearing

prevelo internally routed cables

Internally Routed Cables

prevelo kid size brake and shift levers

Kid Size Hand Brakes and Easy to Use Shimano Rapidfire Shifters



Sealed Bearings

Quick Adjust Seat Height

Built Kid Tough

Confidence Inspiring Geometry


Prevelo Alpha Four Lifestyle



Customer Reviews

4.9 Based on 65 Reviews
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    Brock B.
    United States

    Light weight bike is way to go!

    I purchased this bike last spring for my sons 9th birthday. Light weight with a good gear ratio was my goal for a new bike. I had bought him a Trek for his 7th birthday, but he would never rode it because he couldn’t ride up the smallest of hills in our neighborhood. I finally weighed it one day and realized that it weighed more than my XL 29er full suspension mtn bike...How could that be? So that little Trek was 28.5 pounds, my son weighed 75, thats over a third of his body weight. If that ratio were applied to my bike, my bike would weigh in at 58 pounds?In reality, though it weighs more like 25 lbs and i weigh 170.. so no wonder my son hated riding his bike. If my bike were 58 pounds, it wouldn’t be any fun and would wear me out. After researching most of the big name brands such as Trek Specialized and Cannondale, i realized that they all were excessively too heavy. Front shocks, big knobby tires, look really neat, but those extra items all add dead weight that is absolutely unnesassary for a rider in the 70-100 lb range. Fast forward to today, my son now never hesitates to ride his bike. All the neighbor kids have the “other” heavy bikes, but none of them ride them-ever! My son rides the Alpha Four, all the time. He actually asks me now if i want togo bike riding, that never happened before. We even ride to his school which is 2.8 miles away and mostly up hill. He prides him self on being able to effortlessly ride up the steepest of driveways and those little hills in our subdivision? He flys up them like their not even there. This is what you want, a bike that gets ridden.

    Finnegan W.
    United States

    Best. Bike. Ever.

    My son has struggled to feel comfortable on a gear shift bike for the last several years. Taking him on a ride was always a struggle with lots of complaining that his legs were tired. He LOVES this bike. He asks to go for rides now. He asks, “can we keep going?” And the only complaints I get now are that the rides are too short!

    PHONG D.
    United States

    Our SECOND Prevelo Bike!

    I thought I'd get a Alpha Four bike for myself, so that my 3 Year old (on an Alpha Two) and I could ride together like "twins". The Alpha Four is only a 24-inch and most adult bikes are 28 inch. My wife laughs at me for riding a kids bike, but my son loves it! Both bikes are fantastic build quality. So easy to assemble - within just minutes. Jacob and his team are amazing. Little items that my son breaks, Jacob replaces them at no charge! BUY a Prevelo Bike. Don't even research anywhere else. This is the best family owned bike company around!

    Scott B.
    United States

    Great bike

    My daughter loves her new Alpha 4 and her bike geek Dad does too. For not that much more than a "standard" kids bike by the major brands Prevelo gets you a well put together machine that's lightweight and well spec'd. I've built many bikes myself over the years and I've found nothing to nitpick. Hats off to team Prevelo!

    Scott B. verified customer review of Alpha Four
    Shanti A.

    This is the bike for us

    Hi all, I have been riding bikes for thirty+ years - across a variety of disciplines as well - road, mountain, triathlon... this, along with various sizes of hand-me downs from her older brother, make for a busy garage. When it came time to upgrade my 7yo daughter’s bike, a quick web search brought me to Prevelo Bicycles. Seeing the Alpha Four in person at the Westlake Village showroom sealed the deal. After quickly setting the seat height on the demo bike, my daughter simply climbed aboard and rode away. There really is something to be said about a longish wheelbase, low bottom bracket, low Q-factor (narrow) and shorter crankarms. Jacob let me ride the bike around the parking lot; these bikes are both lightweight and sturdy! Solid frame design coupled with quality components make for a bike she’ll be able to grow with for several years. Yes, these bikes are somewhat more expensive than those you’d find at a big box or dedicated bike shop, but I see it as an investment in my daughter’s riding. She will ride longer and more frequently if the bike is enjoyable. There were some nice touches available to customize the bike, such as handlebar grips and name stickers (both pink) for the seat stays. A third party water bottle and cage round out her new bike. Two thumbs way up for Prevelo!