Fitting a Kid for a Motorbike

Getting your child properly fitted for a motorcycle requires more precision than sizing a push bike. The stakes are higher, the speeds are faster, and the margin for error is smaller. Whether they're starting out on a small trail bike or moving up to something bigger, the right fit directly affects their control, confidence, and safety on the bike.

At On Two Wheels, we regularly fit young riders for motorcycles, and we've learned that taking the time to get the sizing right from the start prevents trouble down the track. Here's what you need to know about fitting kids for their motorbike.

Why Motorbike Fit Matters More Than You Think

An ill-fitting motorbike creates real problems. A bike that's too tall means your child can't reach the ground at stops, leading to tip-overs and lost confidence. A bike that's too heavy or powerful overwhelms their physical strength and coordination, while a bike that's too small cramps their movement and limits their ability to control the bike properly through corners and over terrain.

The right-sized motorbike means your child can comfortably reach the ground with at least one foot, operate the controls without stretching, and maintain their balance when stationary. It means they can actually manage the weight of the bike and develop proper riding technique instead of fighting with a machine that doesn't suit them.

Unlike push bikes, where you might size up for growth, motorbikes need to fit now. The consequences of getting it wrong are immediate and potentially serious.

Key Measurements for Motorbike Sizing

Motorbike fitting relies on similar measurements to push bikes, but how you apply those measurements differs significantly. Much like fitting a kid for a push bike, inseam and height matter, but you also need to consider strength, weight, and riding experience.

Inseam and Seat Height

Inseam remains the most important measurement. Measure from the ground to your child's crotch while they're standing straight in their riding boots (boots add height, so this matters). You can use a soft tape measure to ensure you're getting an accurate measurement.

For motorbikes, seat height is listed in the specifications, usually ranging from about 50cm for the smallest kids' bikes, up to 85cm or more for larger youth models. Your child's inseam should be at least 5 to 10cm longer than the bike's seat height.

Unlike push bikes, your child doesn't need to put both feet flat on the ground, although the requirements change based on their experience level.

If your kid is a complete beginner rider, ground contact is non-negotiable. They should be able to get at least one foot completely flat on the ground when seated, and ideally both feet. This gives them the confidence and stability they need while learning basic balance and control. A 7-year-old on their first bike needs that secure contact to prevent tip-overs and build their skills safely.

For experienced riders, the rules relax. Once they understand weight distribution and balance, they can handle taller bikes where they're reaching with one foot or even on tiptoes with both feet. A confident 12-year-old who's been riding for years can manage a bike where they can't get their feet fully flat, because they've developed the technique to balance and control the bike at stops.

The key is matching the bike to their current ability, not where you hope they'll be in six months.

Height and Overall Proportion

Height gives you a starting point for the bike's engine capacity and overall dimensions. Manufacturers generally recommend:

• 50cc to 70cc bikes: Kids roughly 100cm to 120cm tall (typically ages 5 to 8)
• 70cc to 110cc bikes: Kids roughly 115cm to 140cm tall (typically ages 7 to 11)
• 110cc to 150cc bikes: Kids roughly 130cm to 160cm tall (typically ages 10 to 14)

These ranges overlap because every child's build, strength, and skill level varies. A tall 9-year-old beginner needs different sizing than a smaller 9-year-old who's been riding for three years.

Weight and Strength

This is where motorbike fitting diverges from push bikes entirely. Your child needs to be strong enough to hold up the bike at a standstill, pick it up if it tips over, and control it through rough terrain or at speed.

Most 50cc kids' bikes weigh between 40kg and 50kg, while a 110cc bike might weigh 60kg to 75kg. Can your child manage that weight? Have them try holding a comparable weight or test their ability to keep a stationary bike upright.

If they can't comfortably manage the bike's weight, it doesn't matter if the seat height is perfect. They're not ready for that bike yet.

Reach to Controls

Your child needs to be able to comfortably reach and operate the clutch lever (if applicable), front brake, throttle, and rear brake. Their hands should reach the handlebars without stretching, and their feet should easily find the foot pegs and gear shifter.

Stand them next to a bike and check these points before making a purchase. Many youth bikes have adjustable levers, which help accommodate smaller hands as they grow.

Types of Youth Motorbikes and Sizing Considerations

Different riding styles require slightly different fitting approaches.

Dirt Bikes and Trail Bikes

These are the most common starting point for young riders. Dirt bikes typically have taller seat heights because they're designed for riders to stand and move around on the pegs. This can make them feel intimidating for beginners, but it's actually functional for off-road riding.

For dirt bikes, focus on whether your child can balance the bike while seated and reach the ground adequately at stops. Once they're moving, they'll spend more time standing on the pegs anyway.

Mini Bikes and Pit Bikes

Smaller engine bikes (50cc to 110cc) are designed specifically for younger riders. These usually have lower seat heights and are lighter, making them ideal as first motorbikes. The smaller size allows kids to build skills at their own pace before progressing to full-size youth bikes. Whether it's your son or daughter having their first ride, these bikes are a solid starting point.

Road Bikes and Adventure Bikes

Less common for very young riders, but older kids (12 and up) sometimes start on small road bikes or adventure-style bikes. A street bike requires more precise fitting because road riding demands better control and stability. Seat height and weight become more important when you're dealing with sealed roads and higher speeds. In most places, you'll also need to ensure the bike meets local registration requirements if it's going on public roads. While electric bikes are becoming more common in the push bicycle world, petrol-powered bikes still dominate the youth motorcycle market.

Essential Safety Gear Fitting

Proper safety gear isn't optional for young motorbike riders, and it needs to fit precisely to provide actual protection in a fall or crash. Here's what you need and how it should fit, and remember, all gear should meet relevant safety standards.

Helmets

Motorcycle helmets are far more substantial than push bike helmets, and teaching your kids to wear helmets every single ride establishes good habits that last a lifetime. Measure your child's head circumference about 2cm above the eyebrows, then try helmets in that size range. Many parents make the mistake of buying helmets that are too large, thinking their child will grow into them, but this compromises protection.

A properly fitted child's helmet should feel snug all around the head without any particular pressure points, and it shouldn't move when you gently try to rotate it on their head. Your child should be able to fit one or two fingers between the chin strap and their throat when it's fastened, and the helmet should sit level on their head, not tilted back.

Kids' motorcycle helmets typically range from XS (around 51cm to 52cm) up to L (around 57cm to 58cm). Full-face helmets are strongly recommended for any type of motorbike riding as they provide the most protection. The best way to ensure proper fit is to try multiple brand options, as sizing varies between manufacturers.

Goggles

For off-road riding, kids motorcycle goggles are essential to protect their eyes from dirt, debris, and roost kicked up by other riders. Goggles should fit snugly against the face and seal properly around the eye area without gaps. The strap should hold them securely in place without being so tight that it causes headaches.

Most youth goggles are designed to fit with helmets, so test the combination together. The foam padding should sit comfortably against their face, and they should have clear peripheral vision. Anti-fog lenses are worth the investment, especially for longer rides.

Body Armour and Protection

Chest protectors, back protectors, knee guards, and elbow guards should fit close to the body without restricting movement. Armour that's too loose shifts around in a fall and doesn't protect properly. Armour that's too tight restricts their ability to move and control the bike.

Most youth armour comes in sizes small, medium, and large, but manufacturers vary significantly. Always check specific size charts and, ideally, try it on before you buy.

The armour should stay in place when your child moves through normal riding positions. Have them bend forward (like they're leaning over the handlebars), stand up straight, and twist side to side. Nothing should shift or gap open. Each piece of protection has its proper place and purpose, so don't skip items thinking they're optional.

Boots

Motorcycle boots protect ankles, shins, and feet from impacts and burns. They need to fit snugly but allow enough room for thick socks. Your child should be able to wiggle their toes, but their heel shouldn't lift when they walk.

Youth motorbike boots usually start around size 32 EU (roughly age 5) and go up to adult sizes. Boots add height, which affects how your child reaches the ground on the bike, so always measure the inseam while wearing the boots they'll actually ride in.

Gloves and Pants

Motorcycle gloves should fit snugly without bunching at the fingertips or being so tight that they restrict movement. Your child needs full finger dexterity to operate controls safely. Getting the right glove fit can take some trial and error, but it's worth the effort to avoid blisters or loss of control.

Motorcycle riding pants need to allow full leg movement while staying in place. If they're wearing knee guards underneath (which they should be), make sure the pants fit over the guards comfortably.

Get the Right Fit Before You Commit

If at all possible, have your child sit on the actual bike before you buy it. Check these points:

Can they comfortably reach the ground with at least one foot? Can they hold the bike upright while seated? Can they reach and operate the clutch and brake levers without stretching? Can they reach the foot pegs and controls naturally?

Have them go through the motions of riding. Can they shift their weight forward and back? Can they stand on the pegs? Does anything feel cramped or awkward?

Watch how they handle the bike when it's stationary. If they're struggling to keep it upright or look uncomfortable, it's too big regardless of what the size chart says. A quick test trip around the car park (if possible) gives you the idea of whether the fit is right, and whether they genuinely love riding this particular bike.

When to Size Up

Kids grow quickly, and you might be tempted to buy a bigger bike they can "grow into." Don't. An oversized motorbike is dangerous for a young rider.

The time to size up is when your child outgrows their current bike: when they look cramped on the bike, when their knees are hitting the handlebars, or when they've outgrown the power and need more engine for their skill level. If they're competent and confident on their current bike and it still fits reasonably well, there's no rush. As your child grows, their comfort and control on the bike will naturally diminish, signaling it's time for something bigger.

Most kids will move through two or three different-sized bikes between ages 5 and 14. That's normal and expected. Trying to skip sizes or stretch the usable life of a bike by buying too big creates more problems than it solves. Moving to larger engines should only happen when their skill level and physical development support it, not just because dad thinks they're ready for more power or they want to race their friends.

Need Help Working It Out?

Fitting a child for a motorbike isn't guesswork, but it does require some judgment based on their individual build, strength, and ability. If you're uncertain about sizing, the team at On Two Wheels can help you work through it.

Bring your child's measurements (inseam and height), tell us about their riding experience, and let us know what type of riding they'll be doing. Whether you're sizing up your son or daughter for their first bike or helping them move up to something bigger, we can recommend appropriate bikes from our range and help you understand what they'll realistically be able to handle.

We stock youth motorbikes from Yamaha, Honda, KTM, and Husqvarna, and more, along with a full range of protective gear sized for young riders. If you're not sure about gear sizing, we can fit your child properly in-store rather than guessing online.

Putting It All Together

Getting your child properly fitted for a motorbike takes more consideration than sizing a push bike, but it's worth the effort. With proper fitting, the right bike builds their skills and confidence, whereas the wrong bike creates frustration, accidents, and potentially puts them off riding altogether.

Take the measurements seriously, be honest about their current ability level, and don't rush into a bike that's too big or too powerful. Just as is the case when fitting kids for push bikes, proper sizing makes all the difference between a great experience and a disappointing one.

If you're working out what size your child needs or want to see youth motorbikes in person, visit On Two Wheels at Gledswood Hills. We're always happy to help Sydney families get young riders properly set up on the right motorbike with the right gear.