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

Zulu Three: Ships in about 5 business days
Zulu Three HEIR: Ships in about 5 business days

Wheel Size
20 inches

Approx. Age Range
5½ to 9 years


Trail Optimized

Fast and Free Shipping

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.

Note: Final component spec is slightly different from the image above. See the "Components" section below for a detailed break down of the components included.
The Prevelo Zulu Three packs high performance mountain bike features into a 20-inch wheel size package. Every component is the real deal and is carefully chosen to provide the best performance and fit for young riders ready to tear up the trails. It features:
  1. Prevelo confidence inspiring low and narrow geometry. Prevelo geometry keeps the rider low, balanced and in control.
  2. Zulu specific slack head tube angle keeps the bike controlled over rough terrain.
  3. Lightweight aluminum frame with custom formed 6061 triple- butted tubing and TRAPT™ downtube profile.
  4. Available with a lightweight 80mm travel airfork with HM Carbon Fiber / AL6061 lowers & AL7050 hard anodized 30mm stanchions and adjustable rebound, lockout and compression and 15mm Thru-Axle
  5. Rear hub with 12mm Thru-Axle
  6. Flat mount rear brake caliper keeps the rear brake caliper tucked away and protected between the rear chain stays.
  7. Tektro front and rear hydraulic disc brakes.
  8. Shimano ZEE 10-speed drivetrain. This 10-speed derailleur has a SHIMANO Shadow RD+ Short cage. Because of the small wheel diameter on 20-in bikes, rear derailleurs on 20-inch bikes hang low and close to the ground. The Prevelo Zulu Three uses a high performance short cage derailleurs to keep things high and away from the ground. The derailleur also features a clutch that can be turned on with the flip of a switch to eliminate derailleur bounce over hard terrain and reduce chain drops.
  9. 11-36T wide span gearing gives riders plenty of range to spin up tough hills.
  10. Kid engineered direct mount cranks. All Prevelo cranks are sized specifically for each model bike, down to the millimeter.
  11. 95% assembled. Just install the handlebar, seatpost, frontwheel, and pedals.


Kid Centric Features

prevelo bikes kids mountain bike crank

Kid Engineered Crank

prevelo zulu kids mountain bike disc brake

Tektro Hydraulic Disc Brakes with Flat Mount Rear Caliper

prevelo zulu three kids mountain bike internal cable routing

Internal Cable Routing

Prevelo Confidence Inspiring Geometry
Slack, Long and Low



prevelo kids mountain bike 20 boost rear hub

Rear Hub with 12mm Thru-Axle

prevelo 20 kids mountain bike carbon air fork

Available Carbon Lower Airfork with Adjustable Rebound

zee derailleur

Shimano Zee Drivetrain with 10-speed 11-36T Cassette

kid jumping mountain bike

0% Digital
100% Real


prevelo zulu three 20 kids mountain bike


Customer Reviews

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  • Reviews

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    Terry J.
    United States

    Zulu Three review

    I bought this bike for my daughter because I wanted her to have the best bike available. Having raced at the pro level for over 20 years I'm a strong believer that riding a quality bike makes all the difference. From the construction of the frame to the choice of components it's clear a lot of thought went into this bike. Putting the short cage Zee rear derailleur on it is genius! And the kid sized components are perfect. My daughter had now transitioned from riding on the street to riding trails and no ride goes by without her yelling at the top of her lungs, "This is Awsome!!" I give this bike 5 stars without hesitation! We are very happy with the bike!

    ERIC V.
    United States

    Awesome bike at a good price point

    I am very impressed with the quality of the Prevelo Zulu Three and the attention to order detail that Jacob provided. I ordered a short stem at the same time as the bike for my 5y/o son. Jacob saw that and offered to install the short stem and still provided the standard stem in the box so there was one less thing for me to do when the bike arrive and still left me the larger stem for room to grow. The bike shipped extremely fast, the packaging was good, setup required was minimal and my son loves the bike. His riding and confidence have improved substantially in the past few weeks since delivery and the gearing, 20" wheels/tires, have allowed us to ride trails he was not able to ride before. We are both having more fun as a result. There is no other bike on the market at this price point that includes a real air sprung fork & hydraulic brakes. This is a quality bike that will hold its resale value much better than a lesser quality bike when my son outgrows it in a few years. Very happy with my purchase!

    ERIC V. verified customer review of Zulu ThreeERIC V. verified customer review of Zulu Three
    Mark S.
    United States

    Fantastic Bike

    This is truly a fantastic bike. By using all 'adult' bike parts you end up with a quality bike that can be ridden and maintained. No riveted chainrings and awkward chain guides here. Instead a narrow wide chainring and 10spd, 11-34T cassette will leave your kid climbing like a mountain goat. I was truly shocked by how much terrain my 5 year old could suddenly climb now that he has good gear ratios. Then when we pop out to a road section I just say 'four clicks with your finger' and he's ready to go.

    Mark S. verified customer review of Zulu Three