Alpha Three

Size Guide
Sizing

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
Size
Approx. Rider Age
(years)
Learner Inseam
(inches)
Pedaler Inseam
(inches)
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 to 18 with short seat post
(21.5 to 24 with long seat post)
15 to 17.5 with short seat post
(20.5 to 23.5 with long seat post)
Alpha Three 20" 5 to 9 18 to 23 17.5 to 22.5
Alpha Four 24" 7 to 11 24 to 29 23 to 28
Zulu Three 20" 5½ to 9 21 to 26 20 to 25
Zulu Four 24" 8 to 11 24 to 29 23 to 29

8

In Stock - Ships Fast & FREE!

20-Inch Wheels | V-brakes | 8-Speed

  • The 20" Alpha Three is our smallest geared bike. The 8-speed Shimano drive train and 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 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. 95% assembled. Just install the handlebar, seatpost, front wheel and pedals.
  • MEASUREMENT SPECIFICATION
    Weight (including pedals) 18.9 lbs / 8.6 kg
    Minimum Saddle Height 20.7 in / 525 mm
    Maximum Saddle Height 25.5 in / 648 mm
    Bottom Bracket Height 8.1 in / 205 mm
    Gain Ratio 2.2 - 6.7

    Geometry


    MEASUREMENT SPECIFICATION
    A Wheel Size 20"
    B Wheelbase 32.9 in / 835 mm
    C Effective Top Tube Length 17.4 in / 443 mm
    D Head Angle 69°
    E Seat Tube Angle 71.5°
    F Chain Stay Length 13.8 in / 350 mm
  • Components

    COMPONENT SPECIFICATION
    FRAME 6061 heat treated aluminum alloy custom formed tubing
    FORK Aluminum alloy blades with chromoly steerer tube - 35mm rake
    SEAT CLAMP Aluminum alloy with toolless adjustment
    FRONT BRAKE Tektro aluminum alloy V-brake
    REAR BRAKE Tektro aluminum alloy V-brake
    FRONT BRAKE LEVER Tektro aluminum alloy
    REAR BRAKE LEVER Tektro aluminum alloy
    REAR DERAILLEUR 8-speed Shimano Altus double servo with Smart cage
    SHIFTER REAR Shimano Acera RAPIDFIRE Plus
    FREEWHEEL/CASSETTE Shimano 11-34T
    CRANK SET Prevelo anodized alloy 3-piece square taper with 110MM crank length.
    SPROCKET 32T with double chain ring guard
    BB SET Sealed cartridge
    HEAD SET 1 1/8" threadless
    RIM Aluminum with grinded sidewalls
    FRONT HUB Lightweight alloy 1-piece forged CNC with quick release
    REAR HUB Lightweight alloy 1-piece forged CNC with quick release
    TIRE & TUBE Kenda Small Block Eight Pro 20 ×1.5
    SADDLE Prevelo big kid saddle
    HANDLEBAR Prevelo aluminum big bore - 580mm width x 40mm rise with 31.8mm to 22mm taper
    HANDLEBAR STEM Aluminum 60mm extension
    GRIP Kraton rubber
    PEDAL Composite with 9/16 chromoly axle
  • Trying to decide between the Alpha Three and the Zulu Three? Click here to learn the difference:  Alpha Series vs. Zulu Series

 

What the bicycle media is saying

two wheeling tots logo

Exceptional from top to bottom


tales of mountain mama logo

Excellent

★★★★★


 

Kid Centric Features

kids sized bicycle crank

Kid Engineered Crank


8 Speed Shimano Drivetrain with Wide Span Gearing



Internally Routed Cables


Kid Size Hand Brakes and Easy to Use Shimano Rapidfire Shifters

 

 


Sealed Bearings


Quick Adjust Seat Height


Built Kid Tough


Confidence Inspiring Geometry

 

 

#alphathree

Customer Reviews

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  • Reviews (8)

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JL
07/30/2017
Jason L.
United States

AWESOME!

My son loves this bike. He’s four years old and we ride the beginner trails at the bike park together almost daily. The only thing that’d be better is if my son was tall enough for the Zulu Three. Unfortunately he was a few inches shy of the mark when he needed a new bike. But the good news is my son was tall enough for the Alpha 3! It was the only bike with 20” wheels that I could find to fit him this spring. We upgraded from a Woom 2 with 14” tires and single speed so, initially, it was a big jump up. However, my son quickly adapted and the bigger tires and gears made a huge enjoyment in our biking together. We’re riding about 100 miles per week in serious mountain terrain. Many of the trails we are riding now are rated as intermediate XC trails. This bike has made it a ton of fun to ride together. Everyday he’s keeping up better and better. My son has become my little shredder. On DH trails, he purposely finds every rock he can to ride over and even with multiple hits to various components it’s still going strong. This bike stands up to some serious punishment. We’ve had it for a number of months now with very hard daily use and it holds up. If I’d bought a department store bike it’d be trashed in a week of our riding (not to mention how unsafe it’d be for this type of riding). This bike just keeps going. In contrast to the Prevelo, I’ve seen many “name” brand kids bikes (even those made for 7 - 10 year olds) fall apart on these trails and parents constantly shelling out to fix them over and over again. That means down time from riding (and all the tears/frustrations those kids suffer) and total cost of ownership skyrocketing past the cost of our Prevelo bike. My kid may be the exception at 4 years old doing hardcore mountain biking, but he doesn’t have to be. With a little patience and a passion for biking any kid can become your best biking buddy. I wouldn’t trade anything for the memories my son and I have made this summer riding at the bike park and XC nearly everyday. If you’re hardcore like us and your kid can fit the Zulu, go for it. If they aren’t as hardcore as us and/or can’t fit the Zulu, then get this bike. You won’t be disappointed.

Alpha Three
FY
10/02/2017
F, Y.
United States

Jon Carlos’ Alpha Three

My 5 year old uses it almost everyday for the last 3 weeks. And wants to ride to kindergarten, unfortunately he is not able to ride solo yet (Wife & I work). Although he still needs help on shifting, he is able to keep up with our family bike rides 8+ miles on very hilly terrain. By far the best investment for a very athletic 5 yr old. Thank you for making such a well built kid centric bike, Mr Jacob & the Prevelo team!!! Sincerely; Los Yatco’s from Okinawa, Japan

Alpha Three
KG
08/29/2017
Kyle Gillespie
East Wenatchee, Wa

Very Cool Bike!

I ordered an Alpha 2 and it was a little small so Prevelo graciously let me exchange it for the Alpha 3. Both bikes are are top notch bikes! I've been outfitting my 4 kids with bikes over the past 10 years and these bikes are great because they are light weight and high quality right out of the box.

WF
08/22/2017
William F.
United States

NJ Loves Prevelo Bikes

I bought 2 Alpha Three bikes for my kids. They were delivered to NJ shipping free. I assembled each bike in about 20-30 minutes. I have no experience in assembling bikes at all. pretty easily. My kids stood by me anxious to ride their new bikes. I finished assembling the bikes and off kids went. I adjusted the seat height little bit to get the lower center of gravity that is encouraged with these bikes. I now cannot get the kids off these bikes. They love them and have become such great bicyclists. Great design, durability, and generally really cool. Highly recommend. Looking forward to then next bike we need as well. Thanks, W. Fisher.

JW
07/27/2017
Jason W.
United States

My six year old can bike now!

My daughter was riding on a training wheel bike but could not make the transition to a regular kid's bike until we got her a Prevelo Alpha Three. It is very light and low to the ground, so she felt confident initially just balancing on it and very quickly pedaling on it. Now she can ride it easily and confidently all around. What a great bike for kids!

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