When our kids were ready to start biking, we quickly learned that kids bike sizes are confusing. After making impulse purchases and ending up with bikes that didn’t fit well, we discovered the importance of having the right bike size.
A bike that’s just a few inches too big could lead to injuries and put them off biking for good. One that’s too small can result in frustrations and wasted cash.
We’ve spoken with the experts and studied all the factors involved so we can help you avoid making the same mistakes we did. We’ll guide you in making sense of all this confusion so your child can avoid injury and set off on the best bike for their safety and comfort.
Key Takeaways
- Kids bike sizes are based on wheel diameter, and each size is suitable for different age ranges and heights.
- To find the best bike size, measure your child’s inseam and match it to a suitable wheel size on the chart.
- Ensure your child can safely touch the ground when seated on the bike for proper balance and control.
- The stepover height is important for comfort and preventing injuries, especially for first or second pedal bikes (20-inch to 24-inch sizes).
Kids Bike Size Chart
| Height | Inseam | Age | Wheel size |
| 2 feet, 9 inches to 3 feet, 1 inch | 12 to 14 inches | 2 years | 10 inches |
| 3 feet, 1 inch to 3 feet, 3 inches | 14 to 17 inches | 2 to 3 years | 12 inches |
| 3 feet, 3 inches to 3 feet, 7 inches | 16 to 20 inches | 3 to 4 years | 14 inches |
| 3 feet, 7 inches to 3 feet, 8 inches | 18 to 22 inches | 4 to 5 years | 16 inches |
| 3 feet, 8 inches to 4 feet | 20 to 24 inches | 5 to 6 years | 18 inches |
| 4 feet to 4 feet, 5 inches | 22 to 25 inches | 5 to 8 years | 20 inches |
| 4 feet, 5 inches to 4 feet, 9 inches | 24 to 28 inches | 7 to 11 years | 24 inches |
General Guide
About Kids Bike Sizes
The first thing you’ll probably see when looking for the correct bike is wheel sizes. Kids bike sizes are categorized using the diameter of the wheels. Manufacturers then recommend that wheel size to an age range based on the average child’s height.
We recommend a balance bike as your child’s first bike. A balance bike has no pedals. Wheels on a balance bike can be as small as 10 inches or as big as 14 inches.
The smallest pedal bikes begin with 12-inch wheels. Youth bikes have 24-inch to 26-inch wheels. At 26-inch wheels and beyond, bikes are usually categorized as adult-sized, so we’ll not focus on them in this article.
Narrowing your search to a specific wheel size is only the first step. Smaller or taller children may need to skip to a different age range suitable for their size.
An essential aspect of cycling for beginners is being able to put both feet safely on the ground when they stop. To calculate whether they will be able to reach the ground on a particular-sized bike, you need to know your child’s inseam measurement.
Measuring Your Child for a Bike
To measure your child, you’ll need the following:
- Measuring tape.
- Hardcover book.
- Pencil.
- Blank piece of paper.
- Duct tape.
- Marker.
1. Measure Their Height
Have your child take off their shoes and stand flat against a wall. Use the measuring tape to record their height. Start from their feet up to the top of their head, and jot down the numbers.
It’s Still Important
2. Prep Your Wall
There are several ways you can measure your child’s inseam, but we prefer this one. Grab a blank piece of paper, and attach it to a wall using duct tape. Aim for a height that’s approximately the same as your child’s crotch area.
3. Measure the Inseam
Ask your child to stand against the paper with their feet slightly apart. Place the hardcover book between their legs with the highest point in their crotch.
Have your child step aside, grab your marker, and indicate where the highest point of the book reaches on the paper.
Use the measuring tape to find the height from the ground to the mark. This is your child’s inseam.
4. Find a Wheel Size or Two
With your child’s measurements in hand, look for an appropriate wheel size or two. We say two because even though two bikes have a similar wheel size, the saddle and frame can vary. Some bikes with the same wheel size can have as much as a 5-inch height difference.
Your child may fit both a 12-inch and 14-inch bike. If so, go with the larger wheel size as long as the minimum saddle height matches your child’s inseam.
There will then be room for growth, and it will also help with stability, as large wheels are steadier when riding.
Look at the specs of the bikes you’re interested in, and try your best to match the saddle height with your child’s inseam. If you’re buying online, check out the reviews left by parents and caregivers. Many of the posts will give you a good indication of how the bike will fit.
5. Short Wheelbase vs. Long Wheelbase
A contributing factor to the bike’s size is its wheelbase. The wheelbase is the distance between the center of the back wheel to the center of the front one.
Bikes with a long wheelbase tend to promote a lower center of gravity, which is ideal for beginner riders. It makes it much easier for them to find their balance and maintain it.
A long wheelbase generally means a lower saddle, which is more suitable for young riders. Proper arm extensions and a slightly forward-leaning position are easier to achieve with a long wheelbase.
If the wheelbase distance is short, verify your child’s knees don’t hit the handlebar when they pedal.
The wheelbase is not a typical measurement that manufacturers include in the specs. So, if you’re buying the bike online, look at the distance between the saddle and handlebar. If it seems small, the wheelbase is likely short as well.
Finding a Compatible Bike
1. Balance Bikes
Balance bikes are bicycles without pedals — these focus on establishing balance without adding in pedaling skills (1). They are gaining popularity fast, with many people considering them to be more effective than training wheels. It does, however, depend on the individual child and bike size.
When sizing a balance bike, you never want to go too big. The whole point is that your toddler can push with their legs.
To find the right size, use your child’s inseam measurement to narrow your choices down. Look for a bike with a minimum saddle height of 1 inch to 1.5 inches shorter than your child’s inseam.
Next, have your little one sit in the saddle. While seated, verify that both feet are flat on the ground. Then observe the knees and ensure they’re slightly bent — allowing for optimal leverage as they run.
Next, you should consider the wheelbase. For balance bikes, a long wheelbase is better as it allows the rider to lean slightly forward. It becomes easier to balance and aids the bike’s stability.
2. First Pedal Bike (With Training Wheels)
Training wheels are the old-fashioned way of teaching children how to ride a bike. However, sizing a bike with training wheels differs from balance bikes.
You want to look for a saddle height that’s 1 inch to 3 inches higher than your child’s inseam. For timid children who aren’t fully confident on a bike, go for a height that’s the same as the inseam. Being able to place both feet flat on the ground makes the experience less intimidating.
If your child is confident, they don’t need as much contact with the ground. Have them sit in the saddle, touching the ground with the tips of their toes. When they’re at this height, they can pedal efficiently.
With training wheels, the wheelbase can be a little smaller than on balance bikes. Look for a length that promotes an upright position and allows a natural posture that is less intimidating.
3. First Pedal Bike (Without Training Wheels)
Once the training wheels come off, you must take the seat down a few inches, especially if your child is timid. When losing the training wheels, the bike becomes less stable, and the rider must find their balance while pedaling.
After you’ve narrowed your search to a specific wheel size, look for a saddle height that’s the same as your kiddie’s inseam. Initially, when seated, your child should be able to place both feet flat on the ground to stop if needed.
When your child feels more confident, you can raise the saddle an inch or two. Doing this gives room for proper leg extensions, enabling the rider to pedal efficiently.
Once pedals appear on a bike, manufacturers begin to get more distinctive with design. They start to produce cycles with specific activities in mind, like BMX or mountain biking.
With these types of bikes, the wheelbase will be long, placing the rider in an aggressive position. A forward-leaning stance helps with speed and balancing through turns.
If your youngster simply wants to cruise around the neighborhood, look for a short wheelbase. These promote an upright position — excellent for comfy, laid-back riding.
4. Second Pedal Bike
As your child gets ready for their second pedal bike, they’re likely to be fully confident with brakes and perhaps even gears. It’s essential to choose a size for them that will provide optimal efficiency while pedaling. You want to provide this skilled rider with a satisfactory experience.
For this, find a seat height that is 2 inches to 4 inches higher than your child’s inseam. Once seated, they should be able to touch the ground with only their tiptoes.
For the wheelbase, find a bike that caters to your child’s purpose of riding or whatever feels comfortable to them. Once on their second pedal bike, they’ll be likely to master any position.
Adjustable Seat Height
Although a standard feature on adult bikes, not all kids bicycles allow for seat adjustments. For us, however, it’s a vital component to look for. It can save you cash by letting your child grow and learn with the same bike.
When the time does come, moving on to a new bike will be less intimidating since they will have fully mastered one bicycle already.
When you’re sizing a bike for your child, always aim for the lowest saddle setting and the largest safe wheel size. You want to buy a bike that will allow plenty of room for growth.
If your 4-year-old is tall enough for an 18-inch bike, they may be able to ride it until the age of 7. As long as they feel confident and can reach the ground, they’re good to go.
Stepover Height and Why It’s Important
The stepover height is the height of the top tube on the bike. Manufacturers usually size adult bikes this way — if you can stand comfortably over the frame, the bike fits.
Not all manufacturers state the stepover height in the bicycle’s specs, so it usually requires guesswork on the buyer’s part.
The stepover isn’t as important with small kids bikes like the 12-, 16-, or 18-inch since most are relatively low.
It becomes a particularly important factor as your child gets their first or second pedal bike though. Generally, this will be around the 20- to 24-inch sizes.
When your child stands over the bike (not seated), there should be a gap between the frame and your child’s crotch. Aim for at least an inch or two, especially with boys (2).
The clearance prevents painful injuries should the rider slip forward or when jumping off the seat during a sudden stop. Kids bikes generally have a frame that’s slightly slanted down toward the seat for this reason.
If your youngster is a more aggressive rider or is into BMX racing or mountain biking, a low clearance is best. The rider will then be able to lean more while turning, preserving their speed and balance.
FAQs
How is a Kid’s Bike Size Determined?
A kid’s bike size is determined primarily by the wheel size, which ranges from 12 inches for toddlers to 24 inches for older kids. The key is to match the bike size to your child’s height and inseam for a comfortable and safe riding experience.
How Strict are Bike Weight Limits?
Bike weight limits are quite strict. Overloading a bike can affect its stability and braking efficiency, posing a safety risk. We always urge parents to abide by the manufacturer’s weight guidelines to ensure your child’s safety on the road.
Is it Better to Ride a Bike That’s Too Big or Too Small?
It’s generally safer to err on the side of a bike that’s slightly too small than too big. A bike that’s too large can be hard to control and increases the risk of accidents, whereas a slightly smaller bike offers better manageability for the child.
How Do I Know If My Bike is Too Small For My Child?
If your child’s knees or elbows are cramped, if they seem hunched over, or if their legs are too bent while pedaling, the bike might be too small. Look for a bike where they can comfortably reach the pedals and handlebars without stretching.
How Quickly Do Kids Outgrow Bikes?
Kids can outgrow bikes fairly quickly, often needing a new one every two to three years during their growth spurts. It’s a good idea to get a slightly bigger bike (but not too big) to allow some room for growth.
