Why the right frame size is important

The right bike size is one of the most important factors when buying a bike online. The size of a bicycle is often also called the frame size or frame height and refers to the frame geometry. It specifies the size range in which you can adjust the saddle height and thus your seated position, how long and high the bike is overall and at the same time also determines the riding comfort and handling characteristics. Depending on the manufacturer, the frame size is specified in CM, inches, or from XXS to XXL and includes various factors of the frame geometry.

The right frame size for you

Smartfit calculates the correct frame size based on the following factors: gender, height, inseam length (inner leg length), arm length and riding style.

Our calculator requires gender and height with optional entires for inseam length (length of your inner leg), arm length (distance from shoulder to wrist),

How do I measure inseam length?

Step 1

Take off your shoes and stand against a wall in a straight position to measure. Take a spirit level and clamp it between your legs (a book can also work instead of a spirit level).

step 2

With both hands (in front and behind your body), pull the spirit level or book into your crotch with pressure, as if you were sitting on a saddle.

Step 3

The scale should remain horizontal during the measurement. Now measure the distance from the top edge of the spirit level to the floor. This is your inseam length.

How do I measure arm length?

Step 1

Let your left arm hang loosely and use your right hand to feel outwards over the shoulder blade to the end of the shoulder bone.

Step 2

Now take a tape measure and measure from this point to your wrist. This is your arm length.

Which ride style suits me?

Sporty - If you are looking for a playful and agile riding style for trails and fast corners on the mountain bike, an aerodynamic position with an advantage for all QOM/KOM hunters on the road bike, or a compact position that is good for short rides in the city on a E-bike.

Comfortable - If you prefer a comfortable riding style for long rides with your MTB or touring bike or a more upright position with added comfort for your road bike or gravel bike.

Neutral - If you have no preference.

If you don't have your inseam length ready...

The decisive factor for the size of a bicycle is the frame, or more precisely: the length of the seat tube, i.e. the distance from the middle of the bottom bracket to the end of the seat tube.

In the tables below you will find the frame height that suits your height. The sizes are given either in the well-known clothing sizes XS - XXL, in inches (common for mountain bikes) or in centimeters; you will often find at least two of these units in the description of the bike.

Mountain Bike

This table will help you if you do not know your inseam length:

Road Bike

This table will help you if you do not have the inseam length on hand:

Hybrid Bikes

This table will help you if you do not have the inseam length on hand:

Gravel Bikes

This table will help you if you do not have the inseam length on hand:

Children's bicycles

For adult bikes, the bike size indicates the size of the bike frame, which is different for children's bikes. The sizes, which usually start at 10 inches, refer to the tire size of children's bikes. The smooth transition to an adult bike begins with a tire size of 26 inches. However, you should also know the child's stride length to determine the perfect children's bike size. Age information can often be found in the descriptions of the bikes. Just as children are individualists in all areas of life, they vary in height, so these age information are rather rough guidelines.

A children's bike is also somewhat flexible in terms of size. You can adjust the height of the saddle and handlebars, so a children's bike grows with your little one.