Kids Mountain Bikes vs BMX Bikes

Mountain bikes and BMX are designed for completely different types of roads, riding style and terrains. In this guide, we explain the difference between a mountain bike and a BMX bike and provide some tips on helping to select the bike for anyone in your family.

What are the differences between BMX bikes and mountain bikes?

BMX bikes are designed for riders into tricks, jumps, stunts, urban riding or just showing off at the skate park. In most cases, there’s a single BMX frame size (although you can find BMX bikes for younger children). They all feature slick tyres and a single gear.

For more detailed information on BMX bikes, check out our BMX buyers guide.

BMX bike image

Mountain bikes are designed for riding on tough terrain such as off-road trails. They feature large wheels and robust frames. You’ll find a wide selection of gears, and many mountain bikes feature suspension forks. Mountain bikes aren’t really designed for tricks and jumping at the skatepark, but they are ideal for off-road rides on rugged terrain.

For more information on mountain bikes, check out our mountain bike buyers guide.

Mountain bike image

The key differences between BMX bikes and kids' mountain bikes


Slick BMX tyres are totally different to the knobbly, deeply grooved tyres you'll see on mountain bikes. A different type of grip is needed on typical smooth surfaces such as tarmac, wood, concrete you'll find in skate parks. Mountain bikes, on the other hand, need wide tyres with deep treads to grip muddy paths, gravel, stones and other uneven or wet surfaces.


Many mountain bikes feature heavy-duty disc brakes for powerful stopping on sharp descents. These disc brakes feature a cable system from the brake handle on the handlebars to the brakes themselves that clips in place on the bike frame. On BMX bikes, you're more likely to find a rim brake or V-brake (a brake featuring 2 blocks that squeeze on the tyre, with friction providing the stopping power). This keeps bike weight lower and maintenance easier.

One of the biggest differences between some BMX bikes and certain mountain bikes however is a gyro braking system. Using a clever locking mechanism on the bikes handlebar post, the handlebars on some BMX bikes can be spun in any direction without the brake cable becoming twisted or preventing the handlebars from moving altogether. This is important because certain tricks require riders to spin the handlebars around, so having a brake cable that doesn't get in the way is essential for staying safe while being stylish.


Mountain bikes are indeed designed for going up and down hills. Getting up tough inclines is made an awful lot easier with a decent range of gears to choose from. This enables mountain bike riders to maintain momentum when transferring from riding on the flat, to heading uphill and downhill. Mountain bikes will have a rear cassette with at least 7 gears, and a front chainset with one or more chainrings. You use a lever on the handlebars to changes the gears up and down.

Mountain bike rider on trail

BMX bikes on the other hand are designed for quick sprints between jumps or on freestyle or dirt courses. BMX bikes come with one single, fixed gear. This works well on the flat and for short sprints, but if you want a bike for long leisure rides, you’ll want something with a good selection of gears.

BMX in skate park

Should I buy a BMX or a mountain bike?

Hopefully, but this stage you’ll understand the differences between mountain bikes and BMX bikes. BMX bikes are designed for short sprints and stunts, and while looking super-stylish are unsuitable for long leisure rides. Mountain bikes are bigger and bulkier and are designed for off-road adventures.

If you still can't decide which bike to go for, or you or a family member would like to try some bikes before you buy, pop into your local Halfords store. One of our bike experts will happily talk you through each bike and even set up a short test ride, as well as offering recommendations for whoever is going to be riding the bike.

Spend over £350 on a brand-new bike and we’ll build it for free. For any bike under £350, we charge just £10 for a superb set-up and personalisation for an extra £5. Whether you’re buying a BMX bike or a mountain bike, the best place to get it is Halfords.

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