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Kids bike size guide

A bike that actually fits is the difference between a child who loves riding and one who gives up. Too small and they're cramped; too big and they're not in control. We size by inside leg, not age - children grow at wildly different rates, so age and even height are unreliable on their own. Inside leg tells you the thing that matters: can their feet reach the ground.

How to measure their inside leg

1

Stand them in socks with their back against a wall.

2

Slide a small book between their legs, spine up, and raise it gently until it's snug - like sitting on a saddle.

3

Let them step away, then measure from the top of the book straight down to the floor.

4

That's their inside leg. Pop it into the box below and we'll show you every bike that fits.

Takes two minutes, and it's the single biggest thing you can do to get the right bike first time.

Find every bike that fits

Type their inside leg measurement - the table below filters instantly.

Brand	Model	Inside leg	Height	Age (approx)	Wheel	Type	Gears	Price
woom	woom WOW — Self-Balancing Bike	26– cm	70–100 cm	0.75–3.0 yrs	12" "	Multi-gear	-	£6.90/mo	View →
woom	woom EXPLORE 6	68–85 cm	140–165 cm	10.0–14.0 yrs	26""	Multi-gear	-	£24.50/mo	View →
woom	woom EXPLORE 5	58–72 cm	125–145 cm	7.0–11.0 yrs	24""	Multi-gear	-	£22.50/mo	View →
woom	woom EXPLORE 4	56–71 cm	115–130 cm	6.0–8.0 yrs	20""	Multi-gear	-	£21.00/mo	View →
woom	woom GO 4	51–62 cm	115–130 cm	6.0–8.0 yrs	20""	Multi-gear	-	£20.00/mo	View →
woom	woom GO 3 AUTOMAGIC	44–54 cm	105–120 cm	4.0–6.0 yrs	16""	Multi-gear	-	£19.00/mo	View →
woom	woom GO 3	44–54 cm	105–120 cm	4.0–6.0 yrs	16""	Pedal	-	£17.00/mo	View →
woom	woom GO 2	40–47 cm	95–110 cm	3.0–4.5 yrs	14""	Pedal	-	£15.50/mo	View →
woom	woom GO 1 PLUS	32–40 cm	95–110 cm	3.0–4.5 yrs	14""	Balance	-	£11.50/mo	View →
woom	woom GO 1	25–34 cm	82–100 cm	1.5–3.5 yrs	12""	Balance	-	£9.50/mo	View →

What a right fit looks like

Balance bike: both feet flat on the ground with a slight knee bend - they push and glide with their whole foot.

Pedal bike: on the saddle, the balls of both feet reach the ground comfortably.

Knees clear the handlebars through a full pedal turn, with a relaxed, upright back.

Brake levers reachable without stretching fingers or rolling wrists forward.

Never size up "to grow into."

An oversized bike is harder to balance, harder to stop, and slower to learn on - it costs confidence exactly when confidence matters most. We size for today, always. With free exchanges as they grow, there's simply no reason to compromise: the next size arrives whenever they're ready.

Setting up on arrival +

Arrives 95% assembled - just fit the pedals and handlebars
A genuine 5-minute job: two tools in the box, 90-second video
Set the saddle at hip height standing beside the bike
Run the fit checks above once they're on - done

Adjusting as they grow +

Every bike has months of growth built in
Raise the saddle when their leg looks too bent at the bottom of a pedal turn
Nudge the handlebars up with it
Two small adjustments usually carries the whole size

Signs they've outgrown it

Knees brushing the handlebars as they pedal

Saddle already at its maximum height

Feet flat on the floor, knees clearly bent

They look scrunched, or say it feels "small"

Sound familiar? That's the plan working - exchange to the next size from your account in two minutes.

Re-measure with the finder

Kids bike size guide

How to measure their inside leg

Find every bike that fits

What a right fit looks like

Setting up on arrival +

Adjusting as they grow +

Signs they've outgrown it

How old is your child?

How tall is your child?

What's their riding ability?

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Their perfect fit