A 7-year-old usually needs a 20-inch bike. The average height at this age is about 4 ft (121 cm), squarely in the 20" range (3 ft 9 in-4 ft 5 in / 115-135 cm). Only the smallest kids, under 3 ft 10 in (116 cm), are better off on a 16" a while longer.
- Typical height
- 4′0″ 121 cm; range 3′8″–4′4″ (111–132 cm)
- Their bike
- 20" or 16-inch
- Bike weight
- < 14.8 lb 6.7 kg: 30% of about 49 lb (22 kg)
Calculate with their exact height
How tall is a 7-year-old?
According to the World Health Organization (WHO), half of 7-year-old boys are taller than 47.9 in (121.7 cm) and half of girls are taller than 47.6 in (120.8 cm). Between the 3rd and 97th percentiles (94% of kids) the range is wide: from 3′8″ to 4′4″ (111-132 cm). In the US, the CDC growth charts give a median of 48.0 in (121.8 cm) for boys and 47.8 in (121.5 cm) for girls. That's why age is a guide, but height is what decides the bike: measure your child barefoot against a wall before you buy.
| 3rd percentile | Median | 97th percentile | |
|---|---|---|---|
| Boys | 44.0 in (111.8 cm) | 47.9 in (121.7 cm) | 51.9 in (131.7 cm) |
| Girls | 43.5 in (110.5 cm) | 47.6 in (120.8 cm) | 51.6 in (131.1 cm) |
What size bike they need
A 20" will probably last them until about age 9, so it's a purchase that lasts. If your child is already tall for their age (over 4 ft 3 in / 130 cm), they'll outgrow a 20" soon; in that case, compare it with 24" bikes, which start at about 4 ft 2 in (127 cm) (Woom from 125 cm, Islabikes from 127 cm), although at this age those are usually too heavy for them.
| Size | Height | Inseam |
|---|---|---|
| 16-inch | 3′4″–3′11″ (102–120 cm) | 17–22 in (44–55 cm) |
| 20-inch | 3′9″–4′5″ (115–135 cm) | 20–24 in (50–62 cm) |
How to check the fit
With the pedal at the bottom, the leg almost straight, and seated, they should reach the ground with their toes. Decathlon puts it this way in its 20" manuals: leg fully extended with the pedal at the bottom and still able to touch the ground with the toes. Adjust the handlebar too: arms slightly bent, without putting all their weight on their hands.
Ideal bike weight
At 7, a child weighs about 49 lb (22 kg), so 30% is about 15 lb (6.7 kg). No 20" bike with gears gets that light; good ones come in around 16.5-17.5 lb (7.5-8 kg) (Woom's 20", 17.2 lb / 7.8 kg without pedals).
Brakes: coaster brake or hand brakes
Two hand brakes. V-brakes work well and are easy to adjust; mechanical or hydraulic discs brake better in the rain and take less effort. What matters is that the levers can be adjusted closer to the bar for their hand.
Gears
At 7, they can learn to use gears. The easiest setup: one chainring up front and 6-8 cogs in back, with a trigger or twist shifter. Avoid triple chainrings: more weight, more confusion and more maintenance. If they only ride around a flat town, a single speed is lighter and cheaper.
Training wheels or a balance bike
At this age, training wheels make no sense: if they can't ride yet, start with the balance bike method on their own 16" or 20" bike (pedals off, seat low, gentle slope). A 7-year-old usually learns in a few days.
What to look for when you buy
- Size: almost certainly 20"; check that they can reach the ground with their toes.
- Weight: look for 17.5 lb (8 kg) or less.
- Gears: one chainring and 6-8 cogs, or a single speed for flat areas.
- Skip cheap front suspension: it adds weight and barely moves under a light rider.
- Tires to match the riding: smooth for town, knobby for trails.
Frequently asked questions
What size bike for a 7-year-old?
20 inches. It fits kids from about 3 ft 9 in to 4 ft 5 in (115-135 cm) tall. Only if they're under 3 ft 10 in (116 cm), stick with a 16" a while longer.
Is a 20-inch bike with suspension worth it?
Almost never. Cheap forks are usually too stiff for a child's weight and they add weight. Wide tires are a better choice.
Up to what age does a 20-inch bike fit?
Up to about 4 ft 5 in (135 cm) tall, which is usually around age 9.
Sources
- WHO: Height-for-age, boys 2 to 5 years (percentiles)
- WHO: Height-for-age, girls 2 to 5 years (percentiles)
- WHO: Height-for-age, boys 5 to 19 years (percentiles)
- WHO: Height-for-age, girls 5 to 19 years (percentiles)
- CDC: Growth charts data tables, stature-for-age, 2 to 20 years
- Woom: Compare woom bikes
- Islabikes: Size chart
- Trek: Precaliber kids’ bikes
- Decathlon: Btwin Original 100 20" manual
- Mercê C et al. (2022). Learning to Cycle: From Training Wheels to Balance Bike. IJERPH
- Two Wheeling Tots: Kids’ bike buying guide