two bikes of the same size

Kids Bike Size Guide

Which size Bike infographic

When it comes to size, “one-size-fits-all” is quite a misconception.

Differing wheel sizes need consideration, 10″ or 12″. A 10″ wheel may allow for a lower seat height, but check the maximum seat height so it will still fit when they are older. A quality 12″ no-pedal bike will still achieve low seat positions, but the bigger wheel will avoid speed wobbles. Older children need bigger lightweight first pedal bikes, so consider a 14” or an 18” bike.

Seat height-adjustability is crucial so that the bike will last a few years. The seat height needs to allow a slight bend in the knee, allowing the bike to be walked or run along.


Experts recommend bikes shouldn’t be more than 30% of your child’s weight.

Heavy bikes over 4 kg will prove challenging to manoeuvre. Young children get frustrated easily. We often hear, “my child doesn’t like their bike,” and when we delve deeper, it is because they have a hefty steel bike with incorrect geometry or with stabilisers.

However, the same bike can be a piece of cake for a bigger child. Choose the lightest you can afford without eliminating all the features that make it comfortable.

The Rookie 12″ is 2.9 kg and can be handled comfortably by the smallest riders. The Rookie 14” is just 4.7kg without pedals or 6 kilograms in pedal mode.  Kidvelo Bikes are made from top-quality 6061 aluminium alloy to keep the weight down.

Rookie 12 Geometry


Suitable bike geometry will work with the child to help them learn to balance and manoeuvre, whilst a bike with poor geometry will work against them.

Learning to balance is done by walking, running, and gliding. It’s natural for kids to lean forward when running. But to be able to do so, they need plenty of room.

That said, you need to consider geometry that creates more space between the handlebars and seat post—making it easier to extend the legs for a more comfortable and natural run style while striding. It also means that the handlebar reach is still correct as the child grows bigger.

Watch the step-over height. A low step-over frame is much easier for children to get on and off. On the other hand, some bikes have a very high frame exactly where the child needs to get on and off, making it more difficult. We specify the geometry for all our bikes. Balance Bike Reviews – Cyclesprog explains what they love about our design.


Tyres play a crucial role in the performance and comfort level of a bike.

The type of tyres will determine the smoothness of the ride and the traction achieved on various surfaces. There are four types of tyres used. These include foam, air, plastic, and rubber tyres.

Pneumatic tyres give the most cushioning and traction and are considered the best all-around solution. Foam tyres are cheaper, lighter and generally puncture-proof. However, they lack traction, something we have witnessed firsthand in off-road riding. Rubber tyres are pretty solid, puncture-proof, and have better traction than foam tyres which aren’t comfortable over rough terrain. Plastic or EVA polymer is the lightest but lowest quality and typically only lasts a year. However, 12-inch pneumatics will offer longevity, far longer than a plastic 10″ wheel.

All Kidvelo Bikes come with Alloy rims and pneumatic tyres, perfect for any terrain riding. Our performance wheels are strong and very light.

Rookie 12 Adjustability


All bikes in the Kidvelo range have easy adjustment on the seat height, using quick release clamps and even a scale marked on the post so you can easily fine-tune as children grow. Handlebars that you can set for near or far reach. Our grips are scaled for little hands to give the rider complete control.

Don’t make your purchase based on age alone. There can be a huge difference in leg sizes/inseam between children in the same age group.

6. How to measure a child’s leg size?

Tip! – Measure their inside leg/inseam with shoes on.

Measure your child’s INSEAM. Leg length is critical when gauging the correct size of bike. Please don’t just size a bike by the age of your child. Everyone is different!

The fit: Remember a balance bike is different to a pedal bike as children’s feet need to touch the ground. When sitting on the bike, kids this age should be able to put both feet flat on the ground. This helps children learn balance quickly and prevent tip-over accidents.

  1. Stand the rider straight against a wall
  2. Put a book between their legs
  3. Measure from the top of the book straight down to the floor
  4. That is your child’s inseam

7. Choose the bike to match your child’s ability level

Don’t stress this bit. Our experience has taught us what approximate age children pick up the varying skills required to ride. Kidvelo bikes are sized correctly and consider what skills each age group can handle confidently.

Really young children should start on a straightforward 12″ bike without pedals and brakes. We explain why a Kidvelo is one of the best balance bikes for a 2-year-old

A convertible bike may suit older children. The Rookie 14 (also known as a convertible pedal bike), has lever brakes and transforms into a pedal bike after installing the pedal kit.

Getting a balance bike that also converts to an ergonomic pedal bike makes perfect sense for this age bracket. Older children will need the Rookie 18 version as it is bigger again.

We ask you to consider that Stabilisers on Kids Bikes – They Don’t Work!

8. Transitioning onto pedals

The rider needs to be comfortable with the weight and handling of their balance bike before transitioning to pedals. At Kidvelo, we make this process simple by giving you a larger, slightly heavier bike that you can use without pedals fitted to start. Get used to the increased weight and size and start learning how to use the brakes. Once your child has mastered balance, our unique conversion bike converts to a pedal bike with the easy fit pedal kit. Why buy two bikes when you can have the next generation of kid’s bikes with the Rookie Convertible Balance to pedal bikes. (Arriving Summer 2022). This design gives your child the best chance to learn balance without the complications of pedals. If they aren’t ready,  you can easily remove the pedal kit again.

Rookie 14

Balance or pedalling
For riders 3 - 6 years

Rookie 18

Balance or pedalling
For riders 4 - 8 years

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Don't just take our word for it

  • Kazzi
    5 months ago

    Can't get over the quality of this bike, for the price its phenomenal. All the essential features have been carefully considered and included. I especially like the footrests and reach adjustment the bars and stem enable. Height adjustment is easy and the seat post has measurements too which is really helpful. It's so light a 2-year-old can lift it easily. It was so quick and easy to assemble my 7yo built it with minimal guidance. It's a really good looking bike with good quality robust components. I absolutely love it!

  • Liz Chambers
    4 months ago

    What a fabulous little bike. Bought for my niece as a Christmas present. She is 16 months and absolutely loves it. The bike arrived well packaged, instructions were clear and an absolute bargain for the quality. Thank you so much!

  • Hayley
    3 months ago

    My 3 year old loves his Kidvelo Rookie 12. This is his 1st bike and he's taken to it like a duck to water. He is so confident with it and obviously feels safe. The bike is very fairly priced, it was delivered quickly, its lightweight, easy to put together, and the quality is fantastic. My little one loves the chunky wheels and the bell too. I would definitely recommend this bike to anyone who is looking for their child's first bike.

  • James Kennedy
    1 month ago

    I don’t normally leave reviews, but I’m so impressed with our recent purchase of a Kidvelo bike that I thought this product was worthy of one. The first thing we noticed was the build quality of the product. It’s well made and really sturdy when put together. The black wheels and tyres look great and my little one loves the bright pink colour! I only wish I’d have known about this bike sooner as I would have bought one for my son, who seems to enjoy going on his little sisters bike more than his own! Thanks to all at Kidvelo for making a little girl really happy!

  • Ellie Gentleman
    1 month ago

    Highly recommended Kidvelo Bikes Uk.
    We have the Rookie12 for our little boy. The bike feels super sturdy but lightweight for me to carry around where ever we are going! Super easy to put together my little man even got involved helping me put it together.
    My little one likes the extra features of the foot rest for going down little hills this also really helps with his balance for when he’s ready for the next size bike up.
    As a parent all the extra features with the handle bars and seat as they grow with him so I’m not having a buy a new one weekly is brilliant! “he don’t stop growing “😀
    Also the communication with Kidvelo Bikes Uk was Fantastic and all my questions answered.

  • Nick Jeggo
    2 Days ago

    A Revelation!
    I work as a cycle instructor delivering Bikeability, Learn to Ride and led rides in the Town Park. I'm also the British Cycling Go-Ride lead at my cycling club. The club has been using a Rookie 12 to help keep younger siblings happy while brothers and sisters attend our sessions.
    The bike has been amazing, a revelation in fact. First of all, it's incredibly light, something that everyone comments upon. In fact, when the bike arrived we wondered if the box was empty!
    The steering has proper bearings, as do the hubs, so everything runs really freely. The MTB type handlebar stem is adjustable and the handlebars are shaped so that the reach can be tailored to the rider. The tyres are proper 12" pneumatic with Schrader (car type) valves and the relatively smooth tread pattern means there's the perfect combination of low rolling resistance and grip. There's a choice of 4 colours, but we have the bright green. You certainly can't miss it!
    I've come across lots of balance bikes, but this one stands way above anything else I've seen. You may find some of the features on other bikes, but the rookie 12 has them all in a brilliantly designed combination.
    Buy quality, your kids will thank you for it!

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