Children’s bike sizes are measured by the wheel diameter, typically ranging from 10” on the smallest balance bikes to 26” on the larger bikes for teenagers. What you may notice when shopping around is an abundance of 14” and 16” bikes, but then a jump up to a 20” wheel size. “What about the 18” bike?”, you may ask. Well, you’ve come to right place! In this blog, we discuss why the 18” bike is less common than other sizes, in what cases it can be useful, and the best models available.  

Why 18 Inch Bikes Are Less Common

To understand why bikes with an 18” wheel are less common than other sizes, it’s important to first recognise that children’s bikes are sized not on age, but on inner leg length. The reason manufacturers often don’t make an 18” model is because they overlap the range of inner leg lengths that fit the 16” and 20” models. As an example, consider the 16”-20” Forme bikes and their recommended inside leg measurements:  

• Forme Cubley 16: 45-54cm  
• Forme Cubley 18: 49-59cm 
• Forme Kinder 20: 52-62cm 

As you can see, the recommended inside leg measurements for the Forme Cubley 18 overlap those of the Forme Cubley 16 and Forme Kinder 20. However, that is not to say that 18” wheel sizes aren’t useful. In the following, we go through some of the reasons an 18” wheel size may be the right choice for your child.  

Benefits of 18 Inch Bikes

Suits riders in between sizes

The 18” bike is ideal for children that fit somewhere between a 16” and 20” bike. Children who are on the upper end of the range of recommended inside leg measurements for a 16” bike will probably grow out of it fairly quickly. However, if they would only just fit onto a 20” bike, it can feel like a big step up from a 16” bike. That’s where the 18” bike comes in. It’s perfect for children who would otherwise only make use of a 16” bike for a short while, but who aren’t quite ready to get on a 20” bike. 

Suits taller, less confident riders

Another factor to consider is the jump in complexity from 16” to 20” bikes. Whilst 16” bikes have only one gear, so young riders can focus on pedalling, steering and braking, 20” bikes generally come with the ability to change gears. For children who may still be quite young, but tall for their age, or children who are only learning to ride a bike when they are a bit older, adding gears into the mix may be challenging for them. In those cases, the 18” bike can be a game changer. It retains the simplicity of the 16” bike in that it has only one gear, but is fitted for slightly taller riders, allowing them to ride in comfort and with confidence. 

The Best 18 Inch Bikes Available

At Bike Club, we only stock premium, lightweight bikes that aid children’s learning and enjoyment of cycling. Here’s our selection of three of the best 18” bikes available. 

Forme Cubley 18

• Inner leg: 49-59cm 
• Weight: 7.56kg 

 Lightweight and easy to handle, the Forme Cubley 18 is perfect for young riders who are transitioning to a bigger bike. Its aluminium frame ensures durability while keeping the weight low, making it easier for kids to control. This bike is loved by both parents and children alike! 

Frog 47

• Inner leg: 48-57cm 
• Weight: 6.75kg 

The Frog 47 also offers a lightweight aluminium frame and the ergonomic design ensures a comfortable fit for growing children. The easy-to-reach V-brakes with adjustable levers are perfect for small hands. Available in a variety of appealing colours, the Frog 47 won’t disappoint.  

Cube Numove 180

• Inner leg: 45-52cm 
• Weight: 5.9kg 

The Cube Numove 180 is designed with stability and ease of use in mind, featuring a sturdy yet lightweight aluminium frame and a well-balanced geometry. The chainguard protects both the chain from rust and little legs from oil. It’s low step-over frame makes it easy to mount and get riding. 

Frequently Asked Questions About 18 Inch Bikes

What age is an 18 inch bike suitable for?

18" bikes may suit children aged anywhere between 4 and 7 years old, but it depends on the child’s height and riding ability. It's often a good in-between size for kids who have outgrown a 16" bike but aren’t ready for a 20" bike. 

How do I know if my child needs an 18 inch bike?

Measure your child's inseam and compare it to our bike size chart. Typically, an inseam of around 50-54cm works well with an 18" bike. 

Is it better to buy a bike that's slightly larger so my child can grow into it?

It's usually not recommended to buy a bike that's too big, as a properly fitting bike is essential for safe and confident riding. A bike that's too large can be difficult to control and may make learning to ride harder for your child.

Subscription Kids Bikes With Bike Club

To summarise, 18" bikes a great choice for youngsters who are about to grow out of a 16" bike, but aren’t quite tall enough for a 20" bike or confident enough for a bike with gears. With Bike Club, you don’t need to worry about when they’ll next have a growth spurt and outgrow the bike. You can simply exchange the bike for a bigger one at any time. Check out our range of available kids bikes now.