Quick answer
Match your child's inseam and height to the bike's wheel size and standover clearance. For ages 4–6, the Prevelo Alpha Two (16-inch) fits most riders; for older or more aggressive riders, the Bravo Four (20-inch) offers more travel and control. Always check that your child can touch the ground with both feet while seated.
Bravo Four
Choosing the right kids' bike size isn't just about age—it's about inseam, height, and riding confidence. A bike that's too big feels unstable; too small feels cramped. This guide walks you through Prevelo's sizing logic so you can pick a bike your child will actually enjoy riding.
We'll cover how to measure your child, what to look for in standover height and reach, and how Prevelo models like the Alpha Two and Bravo Four differ in fit. You'll also learn how the Prevelo Trade-Up Club can keep your child on a properly sized bike as they grow.
Measure inseam and height first
Before looking at any bike, measure your child's inseam. Have them stand against a wall in socks, place a book between their legs, and measure from the floor to the top of the book. This inseam measurement is the most reliable starting point for kids bike sizing. Height alone can be misleading because leg length varies widely among children of the same age.
Next, measure their height. Use both numbers together: inseam determines standover clearance, while height helps estimate reach to the handlebars. For a safe fit, your child should be able to stand over the top tube with both feet flat and at least an inch of clearance. When seated, they should be able to touch the ground with the balls of their feet or both feet, depending on their confidence.
- Measure inseam in centimeters or inches—be consistent.
- Re-measure every 3–4 months; kids grow fast.
- If your child is between sizes, size down for easier control.
Match wheel size to age and ability
Prevelo's lineup uses wheel size as a rough guide: 16-inch bikes like the Alpha Two suit ages 4–6, while 20-inch bikes like the Bravo Four fit older or more experienced riders. But age is only a starting point—a tall 5-year-old may need a 20-inch bike, while a cautious 7-year-old might still feel best on a 16-inch. Use the Prevelo bike size chart as a reference, then confirm with inseam and standover.
The Alpha Two is a lightweight 16-inch pedal bike with a single-speed drivetrain and dual hand brakes sized for small hands. It's built for paved streets and gentle dirt paths. The Bravo Four, by contrast, is a 20-inch bike with a Manitou JUNIT Expert fork, 100mm of travel, and a more advanced setup for rougher terrain. The right choice depends on where and how your child rides.
- 16-inch: best for first pedal bikes and neighborhood cruising.
- 20-inch: better for trail riding and kids ready for gears or suspension.
- Consider tire width and tread if your child rides mostly off-road.
Check standover, reach, and brake access
Standover height is the distance from the ground to the top tube. Your child should have at least 1–2 inches of clearance when straddling the bike. Reach—the distance from the saddle to the handlebars—should allow a slight bend in the elbows, not a stretched-out posture. If the reach is too long, your child will struggle to steer and brake confidently.
Brake access matters just as much. The Alpha Two uses dual hand brakes sized for small hands with internally routed cables, so little fingers can reach and squeeze easily. Check that your child can operate the brakes without shifting their grip. If they can't, the bike is too big or the levers need adjustment.
- Standover clearance: 1–2 inches minimum.
- Elbows slightly bent when seated—not locked.
- Brake levers should be reachable without stretching.
Plan for growth with the Trade-Up Club
Kids outgrow bikes quickly. The Prevelo Factory Trade-Up Club is a lifetime membership that gives you 40% back of the original purchase price when you send back your previous Prevelo bike and move up to the next size. Prevelo even pays return shipping. This makes it easier to buy the correct size now without worrying about losing money when your child grows.
If you're unsure between two sizes, the Trade-Up Club reduces the risk of sizing up too early. You can start with a smaller, more manageable bike and trade up when your child is ready. It's a practical way to keep them on a bike that fits, which is the single most important factor in riding confidence and safety.
- Trade-Up Club membership is a one-time purchase.
- 40% back applies to the original purchase price of the previous bike.
- Prevelo covers return shipping.
Decision rules for sizing
- If inseam is under 45 cm (17.7 in): Choose a 16-inch bike like the Alpha Two. Ensure standover clearance of at least 1 inch. Prioritize a lightweight frame and easy-to-reach brakes.
- If inseam is 45–55 cm (17.7–21.7 in): Consider a 20-inch bike like the Bravo Four if your child is confident and rides trails. If they are a beginner, stay with 16-inch until they are comfortable. Match wheel size to ability, not just age.
- If your child is between sizes: Size down for better control and confidence. Use the Prevelo Trade-Up Club to move up when they grow. A slightly smaller bike is safer and more fun than one that's too big.
- If you plan to ride mostly off-road: Choose a bike with suspension and wider tires, like the Bravo Four. Check that the fork travel and tire clearance suit your local trails. Suspension adds weight but improves comfort and control on rough terrain.
Prevelo models at a glance
- Alpha Two: The Alpha Two Mk III is a lightweight, 16-inch pedal bike built for budding riders ages 4 to 6. It has a single-speed HEIR drivetrain with 18T chainring and 10T freewheel, dual hand brakes sized for small hands, and internally routed cables. This makes it an ideal first pedal bike for young children who need simplicity and easy braking on paved paths.
- Bravo Four: The Bravo Four features a Manitou JUNIT Expert fork with 100mm of travel, a 1.5-inch tapered alloy steerer tube, Boost 15x110 axle spacing, and an Expert Air spring system with adjustable rebound and ABS+ damper. It also has HEIR Lock-On Grips and a lightweight 6061 aluminum frame. This bike suits older or more aggressive riders who need suspension and durability for trail riding and rougher terrain.
- Prevelo Factory Trade-Up Club: Members get 40% back of the original purchase price when they send back their previous Prevelo bike and move up to the next size. Prevelo pays return shipping, and membership is for life. This reduces the cost of outgrowing a bike and encourages buying the correct size now rather than guessing.
Who this sizing guide is for
Best for
- Parents buying a first pedal bike for a child ages 4–6
- Families looking to upgrade to a larger Prevelo bike as their child grows
- Riders who want a lightweight, easy-to-handle bike for paved paths and gentle trails
Not for
- Children who need a bike with gears for steep hills or long distances
- Riders looking for a full-suspension mountain bike for technical trails
- Parents who prefer to buy a bike without a trade-up or resale program
Sizing a kids' bike comes down to inseam, standover clearance, and reach—not just age. Use the Prevelo bike size chart as a starting point, then confirm with real measurements. The Alpha Two and Bravo Four cover a wide range of young riders, and the Trade-Up Club makes it affordable to move up as they grow. When in doubt, size down for confidence.
