Bicycle Sizes: Wheel Sizes by Age and Overall Bike Dimensions
Two sizing questions in one place: which wheel size suits a child, and how much space a finished bicycle takes up in a garage, on a rack, in a car or in a shipping box.
Children's bikes are sized by wheel: 12 in for ages 2 to 4, 16 in for 4 to 6, 20 in for 6 to 9 and 24 in for 8 to 11, confirmed by inseam. Adult bikes use 700c/29 in, 27.5 in or 26 in wheels, and a typical adult bike is about 65 to 79 in (165 to 201 cm) long, 40 to 44 in (102 to 112 cm) tall and 16 to 32 in (41 to 81 cm) wide at the bars.
- Age 6–9
- 20 in wheels
- Road bike length
- about 66 in (168 cm)
- 29er MTB length
- 74–79 in
- Parking footprint
- about 6 × 2 ft
On this page
Kids' bike size chart by age, height and inseam
Children's bikes are named by wheel diameter, and every part of the bike scales with it. Age is the rough guide; inseam is the deciding measurement, because the child must be able to put the balls of both feet on the ground from the saddle.
| Wheel size | Typical age | Child height | Inseam |
|---|---|---|---|
| 12 in (balance or pedal) | 2–4 years | 2 ft 10 in – 3 ft 4 in (86–102 cm) | 14–17 in (36–43 cm) |
| 14 in | 3–5 years | 3 ft 1 in – 3 ft 7 in (94–109 cm) | 16–20 in (41–51 cm) |
| 16 in | 4–6 years | 3 ft 5 in – 4 ft 0 in (104–122 cm) | 18–22 in (46–56 cm) |
| 20 in | 6–9 years | 3 ft 10 in – 4 ft 5 in (117–135 cm) | 20–25 in (51–64 cm) |
| 24 in | 8–11 years | 4 ft 3 in – 4 ft 10 in (130–147 cm) | 24–28 in (61–71 cm) |
| 26 in / 27.5 in | 11 years and up | 4 ft 10 in and taller (147 cm+) | 26 in+ (66 cm+) |
Ranges overlap on purpose: a tall 5-year-old may be ready for 16 in wheels while a small 7-year-old is still on 16 in. Lightweight brands with low standover can fit a size earlier than heavy steel bikes with the same wheels.
Checking the fit on a child
- Measure the inseam with the child in shoes, standing against a wall with a book pulled up between the legs. Measure floor to top of the book.
- Compare with the bike's minimum saddle height. For a first pedal bike, the minimum saddle height should be no more than about 1 in (2.5 cm) above the inseam so the child can touch down. Experienced riders can go 2 to 3 in above inseam.
- Check standover. Standing over the top tube, the child needs at least 1 in of clearance.
- Check reach and brakes. Arms should be slightly bent at the grips, and small hands must be able to pull the brake levers fully. Many 12 and 16 in bikes use a coaster (back-pedal) brake for this reason.
Buy the size that fits now, at the lowest saddle setting or near it. A bike one wheel size too big is heavier, harder to stop and the main reason children give up riding. Most kids' bikes have 3 to 4 in of saddle adjustment, which covers about two years of growth.
Adult bicycle wheel sizes
Above 26 in, wheel size no longer indicates the rider's size. It is chosen by bike type, and adults of every height ride the same wheels on different frame sizes. For adult frame sizing by height and inseam, use the bike frame size chart.
| Name | ISO rim (bead seat) | Typical outside diameter with tire | Used on |
|---|---|---|---|
| 700c / 29 in | 622 mm | 26.5–29.3 in (672–744 mm) | Road, gravel, hybrid, most mountain bikes |
| 27.5 in / 650b | 584 mm | 26.7–28.6 in (678–726 mm) | Mountain bikes, small gravel frames |
| 26 in | 559 mm | 26–30 in (660–762 mm) | Older MTBs, cruisers, fat bikes, teen bikes |
| 24 in | 507 mm | about 24 in (610 mm) | Kids aged 8–11, some adult cruisers |
| 20 in | 406 mm | about 20 in (505 mm) | BMX, folding bikes, kids aged 6–9 |
| 16 in (Brompton type) | 349 mm | about 16 in | Compact folding bikes |
The outside diameter depends on tire width: a 700x25c road tire is about 26.5 in across, a 29 × 2.4 in mountain tire about 29.3 in. Both fit the same 622 mm rim. The bicycle tire size chart decodes the markings on the sidewall.
How big is a bicycle? Overall dimensions
A bike's length is roughly its wheelbase plus one wheel diameter, because half a wheel sticks out at each end. Longer-travel mountain bikes have longer wheelbases and bigger tires, so they are the longest common bikes.
| Bike type | Length | Width at handlebars | Height (floor to bars or saddle) |
|---|---|---|---|
| Road bike (700c) | 65–68 in (165–173 cm) | 16–18 in (41–46 cm) | 38–42 in (97–107 cm) |
| Hybrid / city bike | 68–72 in (173–183 cm) | 22–26 in (56–66 cm) | 40–44 in (102–112 cm) |
| Mountain bike, 29 in | 74–79 in (188–201 cm) | 30–31.5 in (76–80 cm) | 40–44 in (102–112 cm) |
| Mountain bike, 27.5 in | 72–76 in (183–193 cm) | 30–31.5 in (76–80 cm) | 40–43 in (102–109 cm) |
| Cruiser (26 in) | 70–74 in (178–188 cm) | 24–30 in (61–76 cm) | 40–44 in (102–112 cm) |
| BMX (20 in) | about 58–62 in (147–157 cm) | 27–30 in (69–76 cm) | about 36 in (91 cm) |
| Longtail cargo bike | 75–90 in (191–229 cm) | 24–28 in (61–71 cm) | 40–45 in (102–114 cm) |
| Front-loader cargo bike | 95–105 in (241–267 cm) | 24–28 in (61–71 cm) | 40–45 in (102–114 cm) |
These are ranges across current models; small and extra-large frames sit at the ends. To get an exact figure for your bike, take the wheelbase from the maker's geometry chart and add the tire's outside diameter, or simply measure from the front of the front tire to the back of the rear tire.
Folding bikes
Folding bikes are sold on their folded size. A Brompton with 16 in (349 mm) wheels folds to about 22 × 23 × 11 in (565 × 585 × 270 mm), small enough for a train luggage rack. Folders with 20 in wheels are larger folded, typically around 30 in (76 cm) long. Check the folded dimensions against your car trunk or storage space before buying.
Storing a bike: wall, ceiling and garage space
- Floor parking: bike-parking design guidance from the APBP plans each bike at about 6 ft long and 2 ft wide (183 × 61 cm). A row of four bikes on the floor therefore needs about 6 × 8 ft, and less if they alternate direction so the bars overlap.
- Vertical wall hooks (hung by the front wheel): the bike projects from the wall by its length and needs a ceiling height of roughly its length plus a few inches, so 6 to 7 ft for most adult bikes. Space hooks about 12 to 18 in apart, alternating heights so handlebars do not clash.
- Horizontal wall mount: needs a clear wall about 6 to 6½ ft wide and projects about as far as the handlebars are wide, so 1½ ft for a road bike and up to 2½ ft for a mountain bike.
- Ceiling hoist: the bike hangs upside down, about 3½ ft deep below the ceiling. Check car roof height and the garage door's travel path first.
For outdoor storage, a 6 × 4 ft shed holds two adult bikes side by side, alternating direction, with nothing else. An 8 × 6 ft shed takes two bikes along the 8 ft back wall (about 3 ft deep with the handlebars staggered) and leaves roughly 3 ft of depth for a push mower and tools. The shed size guide covers larger layouts. Garage door widths and the space beside a car are in the garage door size guide.
Carrying bikes on a car
| Rack type | What to check | Typical figures |
|---|---|---|
| Hitch tray | Receiver size and tire width | 1¼ in or 2 in receivers; standard trays take tires up to about 3 in, fat-bike versions about 5 in |
| Roof, fork mount | Axle standard | Road 12 × 100 mm thru-axle, MTB Boost 15 × 110 mm; adapters for each |
| Roof, upright (wheel on) | Wheelbase and total height | Bike adds 40–45 in to the car's roof height |
| Trunk strap-on | Top tube shape | Step-through and sloping frames may need a top-tube adapter bar |
A bike upright on a roof rack makes an SUV 9 to 10 ft tall. That is more than most residential garage openings (7 to 8 ft) and many parking-garage limits. Note the total height somewhere you will see it before driving in.
Crossbar spread and weight limits are covered in the roof rack size guide. For courts, fields and other sports equipment, see the sports sizes hub.
Frequently asked questions
What size bike for a 10-year-old?
Most 10-year-olds ride 24 in wheels; smaller children of that age may still fit a 20 in bike. The child should be able to sit on the saddle and touch the ground with the balls of both feet, and stand over the top tube with a little clearance.
What age is a 26-inch bike for?
A 26 in bike suits riders from about 11 or 12 years old, roughly 4 ft 10 in (147 cm) and taller, with an inseam of 26 in (66 cm) or more. Adult small frames with 26 or 27.5 in wheels fit the same riders.
Does wheel size tell you the frame size?
Only on kids' bikes. Adult bikes in every frame size share the same wheels, so a small and an extra-large 29er both have 29 in wheels. Adult fit depends on frame size; see the bike frame size chart linked above.
How big is a bike box for shipping?
A bike shop's cardboard shipping box is typically about 54 to 60 in long, 8 to 10 in wide and 28 to 32 in tall (137-152 × 20-25 × 71-81 cm), with the front wheel off, bars turned and pedals removed. That stays within UPS and FedEx package limits of 108 in length and 165 in length plus girth.
Will a bike fit in my car?
With the front wheel removed, an adult road bike is about 50 to 55 in (127 to 140 cm) long and a mountain bike a little longer. That fits behind the front seats of most hatchbacks and SUVs with the rear seats folded. Sedans usually need a trunk, hitch or roof rack.