Size by standover, not by age. Both feet flat or near-flat at a stop, controls reachable with wrists straight, and the bike light enough for the rider to pick up. Start every new rider in the lowest speed mode regardless of age, and treat gear as part of the bike's price: helmet and gloves minimum, every ride, no exceptions.
Parents ask us one question more than any other: what size. Age is the wrong ruler, because a tall 11-year-old and a small 14-year-old need the same bike. Here is the sizing method we use, and where each platform we support fits into it.
How do you size a kid on a dirt bike?
- Standover first. Seated, both feet should reach the ground, flat or close to it. New riders need to catch the bike. A bike a rider cannot catch is the wrong bike, whatever the birthday says.
- Controls second. Wrists straight to the levers, and lever reach adjusted in. Small hands on far levers means late braking.
- Weight third. The rider should be able to lift the bike off themselves and push it up a slope. This rule filters out full-size bikes better than any age chart.
- Power last. Buy the size that fits and limit the speed in software, not the other way around.
Which platforms fit which riders?
| Platform | Rider fit | Notes |
|---|---|---|
| Macfox M16 | Riders from 3'11" up | 500 W, 750 W peak, 16 x 4.0 in wheels. A genuine youth-size frame at $1,099, e-bike class power |
| Segway X160 | Smaller teens | The compact e-moto platform. We stock parts and GUTS seat components under SGX160 |
| Segway X260 | Taller teens | Full teen-size e-moto. Parts cross-map to the Surron catalog, so support runs deep |
| Surron and Talaria class | Experienced older teens and up | These are adult-power machines. Lowest mode first, earned modes after |
The M16 stands apart on this list: it is a moped-style e-bike with e-bike power, which makes it the right first throttle for younger kids. The Segway and Surron-class bikes are e-motos, and the step between those two categories is bigger than any step within them.
Speed modes are the whole system
Every bike we sell in this class has selectable modes. Use them as a license ladder: mode 1 until the braking is boring and automatic, then earn the next one. The parent holds the mode setting, not the rider. It costs nothing and it is the single most effective safety device on the bike.
A real helmet and gloves are the minimum for any ride, and long sleeves, boots and knee coverage belong on dirt. Budget it with the bike: our helmet and glove shelves start well under bike money. And know your local law: most e-motos are off-road only, and minors ride private land and tracks with an adult present.
