The Alpha Three Mk III is a lightweight, 20" geared bike designed for confident young riders ages 5 to 9. Built for adventures on pavement, paths, and light trails, it delivers refined performance, intuitive handling, and a fit that respects growing riders’ proportions.
Key features:
- 8-speed Microshift drivetrain with wide 11–38T gearing and clutched derailleur
- Promax hydraulic disc brakes for consistent, low-effort stopping
- Tubeless-capable double-wall rims
- 20×1.5" Kenda tires
- Integrated handlebar and stem for a clean, ergonomic cockpit
- Rider Supply pod mounts for top tube bag compatibility
- Lightweight aluminum frame with kid-optimized geometry and internal cable routing
Mk III upgrades over Mk II:
- Hydraulic disc brakes
- Clutched Microshift derailleur for secure, silent chain retention
- Tubeless-ready wheels for fewer flats and better traction
- One-piece bar/stem with recessed bolts for a streamlined, snag-free setup
- Rider Supply pod mounts for strap-free gear carrying
At just 16.9 pounds, the Alpha Three Mk III blends low weight with high capability—ready for kids who want to ride further, shift smarter, and stop with confidence.
Use
Paved, dirt paths
Wheel Size
20 in
Age
~ 5 to 9 years
Type
All-purpose Bike
Weight
16.9 lbs
Inseam
19" to 23"
Components
| Frame | Lightweight Triple Butted 6061 Aluminum. Low Center of Gravity, Kid Specific Geometry. Internally routed Cables. 3D Forged Dropouts. Dropper Post Compatible. |
|---|---|
| Fork | Bladed Aluminum Legs with 1 1/8" Aluminum Steer tube |
| Seat Clamp | Aluminum Quick Release |
| Brakes | Promax Hydraulic Disc Brakes |
| Derailleur | Microshift Acolyte Super Short with Springlock chain retention system |
| Shifter | 8 speed Microshift Acolyte Quick Trigger w/ Indicator |
| Freewheel / Cassette | 8 speed 11-38t Microshift H083 |
| Crank | HEIR Lightweight Aluminum 3 piece. Narrow Width, 110mm length |
| Chainring | 28T Narrow Wide with aluminum chain ring guard |
| Bottom Bracket | 68x113 Hollow Square Taper with Sealed Cartridge Bearings |
| Headset | 1⅛" Integrated Threadless Sealed Cartridge |
| Rims | Doublewall Aluminum, tubeless compatible |
| Front Hub | 20h Aluminum Sealed Cartridge with Quick Release Skewer |
| Rear Hub | 20h Aluminum Sealed Cartridge with Hex Key Skewer |
| Tires | Kenda Small Block Eight 20 x 1.5 60 TPI |
| Saddle | Prevelo 1pc Junior |
| Seat Post | ⌀31.6mm alloy 1 piece |
| Handlebar | HEIR Riser Lightweight Aluminum 31.8 clamp, 19mm grip 560mm wide, 25mm rise |
| Stem | Prevelo 1pc bar/stem with knee friendly design |
| Grips | 110mm Black Rubber 19mm diameter Lock-On |
| Pedals | Composite Big Kid, 9/16 LONG Crmo Spindle |
| Version | MK III |
Measurements
| Weight | 16.9 lbs |
|---|---|
| Recommended Inseam | 19" to 23" |
| Minimum Saddle Height | 21.2 in / 540mm |
| Maximum Saddle Height | 26.4 in / 670mm |
| Gain Ratio | 1.78 - 6.12 |
| Max Tire Width | 2.2 in |
Geometry
| Wheel Diameter | 20 in |
|---|---|
| Wheelbase | 33.62 in / 854 mm |
| Chain Stay Length | 13.8 in / 350 mm |
| Head Angle | 68° |
| Seat Tube Angle | 71.5° |
| Seat Tube Length | 11.22 in / 285 mm |
| Effective Top Tube | 17.87 in / 454 mm |
| Bottom Bracket Height | 8 in / 205 mm |
| Bottom Bracket Drop | 1.5 in / 38 mm |
| Stack | 16.18 in / 411 mm |
| Standover | 16.53 in / 420 mm |
| Q Factor | 140mm |
| Reach | 12.48 in / 317 mm |
Shipping Weights & Dimensions
| Box Dimensions | 46.0 in x 8.3 in x 25.5 in |
|---|---|
| Shipping Weight | 24.8 lb |
Specifications and components are subject to variations and change without notice.
Hill Conquering Gear Range
Promax Hydraulic Disc Brakes
Double Wall Tubeless-Ready Rims
Kid Centric Control Center and Integrated Handlebar
Rider Supply Pod Ready
Confidence Inspiring Geometry
Kid Friendly Shifting
Protected Flat Mount Rear Caliper






