When buying a new bike, you naturally want it to be just right for you – which is exactly what you need in order to cycle economically and have long-lasting fun when out and about. The size of your bike frame is calculated according to the type of bike you’re using. The first step in finding the right frame size is to measure your stride length.
Stride length
Your stride length equals the inseam and is an important factor for determining the correct frame size. The easiest way to measure it is to take a spirit level and move it up between your legs until you can’t move it any higher. Now measure the distance between the floor and the spirit level’s upper edge: The resulting number is your stride length.
Tip: You can also use a book if you don’t have a spirit level.
Determining frame size according to bike type
Each bike type’s frame size is different. This holds true for road bikes, triathlon bikes, mountain bikes, trekking and city bikes. The following formulas calculate the right frame size for you.
- Road bike
Stride length x 0,665 = Frame size in cm
- Triathlon bike
(Stride length x 0,665) – 3,5 to 5 cm = Frame size in cm
- Mountain bike
Stride length x 0,57 = Frame size in cm
- Trekking bike and city bike
Stride length x 0,66 = Frame size in cm
Tip: If the result of your calculations falls between two sizes, you should get the smaller frame size if you’re a sporty type. If you prefer to do longer bike tours, the bigger frame will fit your needs better.
Frame height doesn’t equal frame size
Determining the frame size is at best an indication as the individual manufacturers’ frame heights vary. Seceding top tubes, the so-called sloping geometry or integrated saddle posts make it difficult to compare different brands. It’s also common to rank frame sizes from small to large. Once you’ve found the right frame, you can do some finetuning and adjust the stem length, saddle height and stem height on the head tube.
Tip: Always check out the information on the manufacturers’ websites and compare them to your current bike.
The exception: Kids’ bikes
Choosing the correct frame size for children’s bikes is done differently. The frame size is determined by the child’s body size instead of by his or her stride length. The taller the child, the bigger the wheels become.
| Body size (cm) | Frame size (inch) | Age |
| 90-100 | 12 | up to 3 |
| 100-105 | 14 | 3-4 |
| 105-110 | 16 | 4-5 |
| 110-115 | 18 | 5-6 |
| 115-125 | 20 | 6-8 |
| from 125 | 24 | 8-9 |
| from 155 | 26 | from 10 |
Calculation tables
The following tables serve as an additional indication for picking the right frame.
Road bike
| Body size (cm) | Frame size (inch) | Frame size (cm) |
| 155-165 | 19-20 | 48-51 |
| 165-170 | 20-21 | 51-53 |
| 170-175 | 21-22 | 53-55 |
| 175-180 | 22 | 55-57 |
| 180-185 | 22-24 | 57-60 |
| 185-190 | 24 | 60-62 |
| 190-195 | 24-25 | 62-64 |
| 195-200 | 25 | 64 or customised production |
Mountain bike
| Body size (cm) | Frame size (inch) | Frame size (cm) |
| 155-165 | 15-16 | 38-41 |
| 165-170 | 16-17 | 41-43 |
| 170-175 | 17-18 | 43-46 |
| 175-180 | 18-19 | 46-48 |
| 180-185 | 19-20 | 48-51 |
| 185-190 | 20-21 | 51-53 |
| 190-195 | 22-23 | 56-58 |
Trekking and city bike
| Body size (cm) | Frame size (inch) | Frame size (cm) |
| 155-165 | 19-20 | 47-50 |
| 165-170 | 20-21 | 50-52 |
| 170-175 | 21-22 | 52-55 |
| 175-180 | 22-23 | 55-58 |
| 180-185 | 23-24 | 58-61 |
| 185-190 | 24-25 | 61-63 |
| 190-195 | 25-26 | 63-66 |
| 195-200 | 26 | 66 upwards |
Tip: To determine the right size, do a test drive at the bike shop to get a feel for the bike.
Have you found the right frame size? 🚴🏻
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