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How to find out the right frame size for your bike

What role does frame height play on a bicycle?

The frame height, also known as the frame size, is one of the classic measurements for determining the size of a bicycle. The frame height indicates the value from the middle of the bottom bracket to the end of the seat tube - this measurement method is called “center-to-top”.

How do I know the frame size?

You cannot read the frame height of a bicycle directly on the frame; you have to measure it yourself.

What is the difference between frame size and wheel size?

The two terms are easily confused. The distinction is actually quite simple: the wheel size specified for your bike corresponds to the diameter of the tires on the bike and is almost always specified in inches (for example 26 inches or 28 inches). The frame size, on the other hand, indicates how large the distance is between the pedal axle of the bicycle and the end of the seat tube. In contrast to the wheel size, the frame size of a bike in Germany is usually measured in centimeters.

How do I calculate the right frame height for me?

You can determine the optimal frame size for you by measuring your correct stride length and then multiplying it by a certain factor, which varies depending on the type of bike. As a result, you will receive the frame size that is right for you in centimeters.

Step 1: Determine the correct stride length

You can measure the stride length, i.e. the length of the inside of your legs, using a ruler or tape measure. Tip: Take the measurement without shoes or pants so that the result is not distorted. To do this, clamp a spirit level or a book at the top between your legs. Then measure the distance from the floor to the top edge of the book or spirit level. The value determined is your stride length.

Step 2: Multiply the stride length depending on the type of bike

Due to the different frame geometries, there is a specific multiplication factor for each type of bike. Depending on which type of bike (mountain bike, e-bike, racing bike, etc.) you are interested in, you will need to multiply your determined step height by one of the following factors in order to determine the correct frame size .

Mountain bikes: stride length x 0.226 = cm frame size
Trekking, city, e-bikes: stride length x 0.66 = cm frame size

Road bikes: stride length x 0.665 = cm frame size

SUSHI BIKE Maki 3.0:
S: Inside leg length from 76 cm
M: Inside leg length from 79 cm
L: Inside leg length from 83 cm 

Good to know: If the calculated value is between two frame heights specified by a manufacturer, you should tend towards the smaller frame for a sporty driving style and the larger frame for a leisurely driving style.

Can the correct bike size also be estimated based on body height?
Instead of the exact frame height in centimeters, many bicycle manufacturers use clothing sizes S, M, L and XL for the size specifications of their bikes. Which body size is suitable for which bike size varies from manufacturer to manufacturer. For example, sometimes a frame with a height of M may be suitable for your individual stride length, but other times perhaps a frame with a height of L. This is why there is often an additional orientation based on the rider's height (e.g. between 170cm and 180cm). For example, with our new e-bike model Maki 3.0 we use the following classification:

SUSHI BIKE Maki 3.0:
S (under 172cm) at SUSHI BIKES 50 cm frame height
M (173-179cm) at SUSHI BIKES 55 cm frame height
L (over 180cm) at SUSHI BIKES 60 cm frame height

If such guidance is missing, you should contact the bicycle manufacturer (or the frame manufacturer).

How do I find the perfect bike frame for me?

The value from the frame size calculation is always just an approximation to find the perfect bike frame for you. In the end: Trying is more important than studying. Even an exact calculation does not replace a test ride with the new bike and does not take your personal preferences into account. In the end, only through your own experience can you say with certainty whether the frame geometry and height suits your own body type and riding experience.

Good to know: Almost every bicycle or e-bike can be customized later. A longer stem or a flexible seat post gives you leeway, even if the frame height of the bike doesn't fit you exactly to the centimeter.

What are the risks when riding with the wrong frame size?
The correct frame height is an essential factor when choosing the bike size. Ultimately, the frame size has a particular influence on the rider’s position on the bike. If the frame doesn't match your stride length, it will be difficult to effectively transfer power to the pedals. Your posture also becomes less favorable: if the frame is too small, your body will have to bend over. Frames that are too large lead to stretched and strained joints.
Back problems or pain in the leg muscles are often a sign of the wrong frame size, especially on longer tours. In addition, riding a bike with a frame that is too small or too big is simply no fun! For this reason alone, the frame height should be precisely measured and calculated before every bike purchase.
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