Bike Size Guide
Enter your height to get the frame size to shop for, then check it against the full chart. Wheel, tyre width and tyre pressure for every kind of bike are further down.
Drop bars, 700c wheels, narrow tyres. Sized by seat-tube length in centimetres.
Road size chart
Every brand shifts these by a centimetre or two — treat the chart as the starting point, then test-ride.
| Size | Frame (seat tube) | Rider height | Inside leg | Notes |
|---|---|---|---|---|
| XXS | 44–46 cm | 147–155 cm (4'10"–5'1") | 66–70 cm | Often built around 650b wheels to keep the front end low. |
| XS | 47–49 cm | 155–162 cm (5'1"–5'4") | 70–74 cm | — |
| S | 50–52 cm | 162–170 cm (5'4"–5'7") | 74–78 cm | — |
| M | 53–54 cm | 170–176 cm (5'7"–5'9") | 78–81 cm | The most common adult size — easiest to find second-hand. |
| M/L | 55–56 cm | 176–182 cm (5'9"–6'0") | 81–84 cm | — |
| L | 57–58 cm | 182–188 cm (6'0"–6'2") | 84–87 cm | — |
| XL | 59–61 cm | 188–196 cm (6'2"–6'5") | 87–92 cm | — |
| XXL | 62–64 cm | 196–203 cm (6'5"–6'8") | 92–96 cm | Stock is thin above 61 cm; check stem and crank length too. |
- Aim for 2–3 cm of standover clearance over the top tube.
- Modern road frames are sized by stack and reach as much as seat tube — two 54s from different brands can fit very differently.
- Between sizes? Take the smaller frame and add a longer stem or more seatpost. A frame that is too long is much harder to correct.
Bike types, wheels and tyre pressure
Cold pressures for a rider around 70–75 kg. Need other units? The pressure converter handles psi, bar, kPa and atm.
| Bike | Wheel | Tyre width | Tyre pressure | Notes |
|---|---|---|---|---|
| Road (23–25 mm, tubed) | 700c | 23–25 mm | 80–100 psi (5.5–6.9 bar) | The old "120 psi" habit is slower and harsher on real roads. Lower end for lighter riders. |
| Road (28–32 mm, tubeless) | 700c | 28–32 mm | 55–75 psi (3.8–5.2 bar) | Wider tubeless rubber rolls faster at lower pressure. Never go under the rim maker's minimum. |
| Gravel | 700c / 650b | 38–50 mm | 25–40 psi (1.7–2.8 bar) | Low 20s for loose or rocky ground; the top of the range for tarmac transfers. |
| Mountain — XC / trail | 29" / 27.5" | 2.2–2.5" | 20–30 psi (1.4–2.1 bar) | Run the front 1–2 psi below the rear for grip. Tubeless lets you drop roughly 5 psi lower than tubes. |
| Mountain — enduro / downhill | 29" / 27.5" | 2.4–2.6" | 22–32 psi (1.5–2.2 bar) | Heavier casings and rim inserts allow lower pressure without burping or rim strikes. |
| Fat bike | 26" / 27.5" | 3.8–5.0" | 5–15 psi (0.3–1.0 bar) | Single digits for soft snow and sand, 12–15 psi on hard trail. Needs a low-pressure gauge to set at all. |
| Hybrid / commuter | 700c / 27.5" | 32–42 mm | 50–70 psi (3.4–4.8 bar) | Top of the range when you are carrying panniers or a heavy load. |
| City / Dutch | 700c / 26" | 37–47 mm | 40–65 psi (2.8–4.5 bar) | Comfort first. Check monthly — these are the tyres most often ridden flat. |
| E-bike | 700c / 27.5" | 42–62 mm | 35–55 psi (2.4–3.8 bar) | Add roughly 10% over the same tyre on an unpowered bike — motor and battery add 8–12 kg. |
| Kids | 12"–24" | 1.75–2.25" | 20–40 psi (1.4–2.8 bar) | Light riders need far less than the sidewall maximum. Lower pressure grips better on gravel and grass. |
| BMX | 20" | 1.75–2.4" | 45–70 psi (3.1–4.8 bar) | Park and street run high for pop; dirt and race run lower for grip. |
Adjusting the pressure to you
Rider weight: add or subtract roughly 1 psi per 5 kg above or below 70 kg on a road bike, and 1 psi per 10 kg on a mountain bike.
Front vs rear: the rear carries more weight — run it 5–10% higher than the front.
Never exceed the maximum printed on the tyre sidewall, or the minimum quoted by a tubeless rim maker.
Check weekly. A narrow road tyre loses several psi in a week; a big mountain tyre holds pressure far longer.
Measuring and the formulas behind the chart
Height: shoes off, back to a wall, heels together.
Inside leg: shoes off, feet 15–20 cm apart, pull a book up firmly into your crotch and measure from the top of the book to the floor.
Road / gravel frame (cm) = inside leg (cm) × 0.665
Flat-bar frame (cm) = inside leg (cm) × 0.63, then ÷ 2.54 for inches
Saddle height (BB to saddle top) = inside leg (cm) × 0.883
Inside leg is normally about 46% of standing height, which is what the optional field is pre-filled against.
Instructions
Turns a rider's height into the bike frame size to shop for, and collects the wheel, tyre width and tyre pressure numbers for each kind of bike in one place.
- Pick the bike type — road, gravel, mountain, hybrid or kids. Each discipline has its own chart and its own way of labelling sizes.
- Enter your height, in cm or in feet and inches. The recommended size appears immediately and is highlighted in the chart below.
- Optionally add your inside leg for a frame size from the classic formula plus a starting saddle height.
- Scroll to Bike types, wheels and tyre pressure for wheel size, tyre width and the pressure range each kind of bike runs.
Tips
- Height gets you the right size to try; inside leg is the better predictor, and reach decides it. Two riders the same height can correctly choose different sizes.
- When you land within 2 cm of a size boundary the neighbouring size is flagged too — ride both. On drop-bar bikes, the smaller frame is the safer bet, because a long stem is an easy fix and a short one is not.
- Kids' bikes are sized by wheel diameter, not frame, and the age column is only a rough guide. Never buy a size up to grow into.
- Tyre pressures are cold values for a ~70–75 kg rider. Adjust for your weight, keep the front a little lower than the rear, and stay inside the tyre and rim limits.
- Everything here is computed in your browser and your entries are kept in local storage on this device only — nothing is sent anywhere.
- Hit Example, then click a bike-type button or the height field to load a typical rider for that discipline.