Stand against a wall with a book between your legs, snug like a saddle. Measure floor to the top of the book.
Frame size from your height
19 to 20 inch (55 to 57 cm)
Size L on UK retailer charts for 176 cm.
Frame size from your inside leg
53 cm
Inside leg estimated at 83 cm, 47% of height. Measure it for a firmer answer.
How the size is worked out
Height goes into the size charts UK retailers publish, here the Wheelbase charts for road, hybrid and mountain bikes. Each chart is a set of height bands with a frame size in centimetres or inches and a letter size. A height on the line between two bands returns both, because that is the honest answer.
Inside leg goes into the formula bike fitters have used since the 1980s, credited to the French coach Cyrille Guimard: inside leg in centimetres times 0.67 gives a road frame, times 0.64 a hybrid or trekking frame, and the road figure minus 11 cm converted to inches gives a mountain frame. When you do not enter an inside leg the tool estimates it at 47% of your height and says so.
Bikes for children are sized by wheel, using the inside leg thresholds Frog Bikes publishes: 40 cm for 14 inch wheels, then 44, 47, 53, 61 and 67 cm for 16 to 26 inch. Brompton makes one frame size and quotes a fit range of 140 to 203 cm, so the tool only checks that you are inside it.
UK bike size charts by height
The bands the calculator reads. Heights are given in centimetres; a height on a boundary fits either size.
| Height | Frame (cm) | Size |
|---|---|---|
| 148 to 152 cm | 47 to 48 cm | XXS |
| 152 to 160 cm | 49 to 50 cm | XS |
| 160 to 168 cm | 51 to 53 cm | S |
| 168 to 175 cm | 54 to 55 cm | M |
| 175 to 183 cm | 56 to 58 cm | L |
| 183 to 191 cm | 58 to 60 cm | XL |
| 191 to 198 cm | 61 to 63 cm | XXL |
| Height | Frame (inch and cm) | Size |
|---|---|---|
| 147 to 155 cm | 13 to 14 inch (47 to 49 cm) | XS |
| 155 to 165 cm | 15 to 16 inch (50 to 52 cm) | S |
| 165 to 175 cm | 17 to 18 inch (53 to 54 cm) | M |
| 175 to 183 cm | 19 to 20 inch (55 to 57 cm) | L |
| 183 to 191 cm | 21 to 22 inch (58 to 61 cm) | XL |
| 191 to 198 cm | 23 to 25 inch (61 to 63 cm) | XXL |
| Height | Frame (inch) | Size |
|---|---|---|
| 148 to 158 cm | 13 to 14 inch | XS |
| 158 to 168 cm | 15 to 16 inch | S |
| 168 to 178 cm | 17 to 18 inch | M |
| 178 to 185 cm | 19 to 20 inch | L |
| 185 to 193 cm | 21 to 22 inch | XL |
| 193 to 198 cm | 23 to 24 inch | XXL |
| Inside leg from | Wheel size | Typical age |
|---|---|---|
| 40 cm | 14 inch | 3 to 4 |
| 44 cm | 16 inch | 4 to 5 |
| 47 cm | 18 inch | 4 to 6 |
| 53 cm | 20 inch | 5 to 7 |
| 61 cm | 24 inch | 8 to 10 |
| 67 cm | 26 inch | 10 to 12 |
Getting the fit right on the bike
The frame size gets you to the right bike. Saddle height, saddle position and bar height then decide whether it feels right, and a shop or a mechanic can set them in a few minutes. If you are between two frame sizes, ride both before you decide.
Already have the bike? A full service at your door goes over the whole bike, and our guides cover the fixes you can do yourself.
Bike size questions, answered
Where the numbers come from
- Wheelbase, bike sizing chart Road, hybrid and mountain bike height bands used in the calculator.
- Omni Calculator, bike size calculator The Guimard inside leg formula and the 47% inside leg estimate.
- Halfords, bike size guide Inside leg times 0.67 minus 5 inches for a mountain frame, the same formula in inches.
- Edinburgh Bicycle Cooperative, Frog bikes size chart Inside leg thresholds for each wheel size.
- Edinburgh Bicycle Cooperative, Brompton sizing guide One frame size, fit range and handlebar types.
Bike sorted? Keep it that way.
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