Balance Bike

Why size goes by seat height and inside leg

Age says little about whether a balance bike fits; legs say almost everything. Seated, the rider must be able to rest both feet on the ground, push off, then lift them and glide. So the measurement that matters is the rider's inside leg, set against the saddle height of the bike.

To measure inside leg, the rider stands with their back to a wall, wearing the shoes they will ride in, with a hardback book held level between the legs, spine upwards. Read the height from the floor up to the top of the spine, in millimetres or inches. While learning, keep the saddle a little below that figure, so the rider can sit with knees slightly bent and both soles down. As confidence grows, raise it towards the inside-leg figure.

Every bike lists a lowest and a highest saddle height. Pick one where the rider's starting height sits near the bottom of that range, which leaves room to raise it later. Check how far forward the handlebar sits as well: the rider should steer with relaxed arms, without leaning far forward or knocking their knees on the bars.

14-, 16- and 20-inch: what changes as the wheels grow

Wheel size follows the frame. A 14-inch balance bike is the step up from the smallest sizes. A 16-inch balance bike brings a longer frame, a higher saddle range and more room for growing legs. A 20-inch balance bike is the size used by taller teenagers and adults, and some adult learners get the same effect by lowering the saddle of a small pedal bike and taking the pedals off.

Bigger wheels roll over bumps with less fuss and keep their speed for longer between pushes. They also make the bike heavier and quicker, which is why brakes start to matter at these sizes. A bigger balance bike is not just a stretched small one: frame shape, steering and brakes all change with it.

Brakes and tyres on a bigger balance bike

On the smallest balance bikes, feet do the braking. Once the wheels reach 14 inches and the rider is heavier, feet alone take too long to stop, and shoe soles wear through fast. A hand brake on the rear wheel is the usual answer. Check that the lever sits within easy reach and that the rider can squeeze it fully with two fingers, because a balance bike with brakes only helps when the lever suits the rider's hand.

Tyres change the ride as much as the frame does. Tyres you pump up give more grip and cushioning than foam, yet a thorn can flatten them and they need topping up. Foam tyres never go flat and weigh less, though they give a harder, slippier ride on rough or damp ground. Solid rubber sits somewhere in between. Balance bike wheel and tyre choices come down to where the bike will be used: smooth paths, or grass and gravel.

Electric balance bikes: the rule

An electric balance bike has a motor and no pedals, so it is not an e-bike in law. Use it only on private land, with the landowner's permission, under adult supervision.

A motor also brings a battery and a charger to look after, so follow the maker's charging instructions to the letter.

Toy or not: the 435 mm seat-height line

British product rules draw a line at the saddle. A bicycle whose saddle cannot be raised above 435 mm, measured from the ground to the top of the seat with the seat post pulled up to its minimum-insertion mark, comes under the rules for toys. A bike on that side of the line has to carry this warning, word for word:

‘Warning. Protective equipment should be worn. Not to be used in traffic.’

Information that shapes the decision to buy, such as an age warning, also has to be visible before you pay, online as well as in a shop. A large balance bike whose saddle goes higher than 435 mm falls outside those rules, so it may carry no such warning and no age range at all. That says nothing about its quality; it means the fit checks on this page are yours to do.

Learning to cycle as a grown-up

Plenty of adults never learned to ride a bike, and a balance bike makes a calm start: no pedals to think about, both feet ready to catch you, and progress you can feel early on.

Start on a smooth, level surface on private ground, well away from traffic. Walk the bike while sitting on it, then take longer pushes, then lift both feet and glide for a count of three, then five. Keep your gaze up and well ahead of the front wheel. Once straight glides and a gentle curve with your feet up feel easy, pedals are the next step.

Braking comes in early on a bigger bike. Practise squeezing the hand brake while gliding slowly, so that stopping with the lever becomes as natural as putting your feet down.

For many adult learners, an e-bike comes next, because the motor helps on the first uphill stretches. If that is your plan, start with what to check on an e-bike for adults.

Sources we checked (last checked 25 October 2026):

• Riding an electric bike: the rules (GOV.UK)
• The Toys (Safety) Regulations 2011, Schedule 1 (legislation.gov.uk)
• The Toys (Safety) Regulations 2011, Schedule 5 (legislation.gov.uk)
• The Toys (Safety) Regulations 2011, regulation 20 (legislation.gov.uk)