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 16.5 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


16
Same day shipping on orders placed Mon-Fri by Noon PST.


Wheel Size
20 inches

Approx. Age Range
5 to 9 years

Speeds
8


Fast and Free Shipping
Orders in by 12 noon PST M-F ship same day.
(except holidays)

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

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

  • 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
  • Kickstand

    • Custom sized for the Prevelo Alpha Three
    • If you order a kickstand with a bike, it will come installed on the bike
    • Lightweight aluminium alloy
    • Non-corrosive, solid non-porous casting
    • Dual spring pressure plate and snap action mechanism with hardened steel pivot pin
    • Non-slip clamping surface
    • Made in USA

     

    Custom Color Grips

    Customize your new Prevelo with grips in the rider's favorite color. Made for Prevelo out of 100% silicone by ESI in Southern California.  We will install the grips on your Alpha Three before shipping.

    custom grip colorsprevelo custom colored grips

     

    Rider Name Lettering

    • Custom cut out of 2.5 mil vinyl right here at Prevelo HQ in California and applied to BOTH seatstays before shipment.
    • With a bit of work the decal can be removed when it comes time to hand the bike down.

     


 

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

Based on 16 reviews
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  • Reviews (16)

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MZ
01/26/2018
Michael Z.
United States

Great Setup, Great Value

I purchased the Alpha Three for my 5-1/2 year old son after researching pretty much all options in the 20” kid bike category. I settled on the Alpha Three because it had the best combination of all the attributes important to me – a good gear ratio, lightweight, trigger shifting, and accommodating standover height, all for a reasonable price tag. I really like the gear ratio Prevelo chose with the 32T up front and the 11-34T in the rear. A wide gear ratio including low gearing was important to me considering the hilly terrain we live in. Needless to say, my son (not the strongest kid) can power up hills much steeper than I thought possible for him. All of the comparable bikes, other than the pure mountain bikes, have gear ratio ranges that are very narrow and are more for flat, less hilly terrain. In my mind, it is more important for a little kid to easily get up a hill than attain top speed on the flats. My only recommendation would be to maybe even go a bit further to something like a 30T in the front and 11-36T in the back for even more range and good climbing ability. The trigger shifter was also another must for me. The main choice in shifters for kid bikes is either the trigger or twist grip. The reason I like the trigger is because that is what most big kid/adult hybrid, fitness, and mountain bikes use, not grip shifters, so why not learn to use what just about everyone else uses? My son is on the smaller side with small hands and he had zero issue with using the trigger shifter on the Alpha three. I think the combination large gear ratio and trigger shifter offering on the Alpha Three is a huge differentiator because no other comparable bikes come close. Really great bike that a kid can confidently ride on the pavement and the dirt/gravel at a great value for the components you get. I agree with the other reviewers in that the interactions I had with the Prevelo team were great – very prompt, helpful, amazing customer service, and the assembly of the bike was a breeze. Keep up the good work!

KF
12/31/2017
Kate F.

Absolutely Brilliant Bike

I wish I had found Prevelo sooner. The bike we bought our youngest son (aged 5) today is light weight, designed perfectly for him and had him riding within minutes. He has had a gliding bike for a few years, and is over the moon to finally be pedalling and keeping up with his 10 year old brother. It’s an absolutely brilliant bike, well worth the money, and I highly recommend it.

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
A
01/08/2018
Anonymous
United States

Great product and service

I'm in CA and the bike was delivered within 4 or 5 days. It was easy to assemble and was in perfect condition. The sizing recommendations were perfect for my 6.5 year old daughter. She loves the bike!

A
01/02/2018
Anonymous
United States

Cincinnati -5 degrees

Give me a couple weeks and surely we'll have some warm enough days to ride. But, the bike was super easy to assemble. But, I have had lots of experience with this.

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