Framework calculation
The inseam is the most important prerequisite for choosing the right bike size!
The question of which bike is best for which age can only be answered to a limited extent. There are children who are six years old and 120 cm tall, and there are six-year-olds who are not even 100 cm tall. As a result, children need bikes of different sizes despite being the same age.
The child's inside leg length is crucial when choosing the bike size. The inside leg length describes the distance between the ground and the crotch. It gives you information about whether a child can still touch the ground with their feet when the saddle is set very low. The possible contact with the ground is always an important feature when buying a bike for children. This is particularly important when children are still learning to ride a bike, because contact with the ground gives them security. In this respect, the child's height can only be a guide. In normally developed children, stride length and height are in a certain ratio. Nevertheless, experts always recommend measuring the stride length to avoid disappointment.
Calculate the frame height easily by determining your correct stride length (step height)!
You need a folding rule and a spirit level. If you don't have a spirit level, you can easily use a book. Take off your shoes and trousers (depending on how the trousers are cut, this will affect the measurement result). If you have a spirit level, pull it up between your legs as horizontally as possible (see drawing on the right). It works the same with a book, but you should stand against a door or wall so that the top edge of your 'measuring instrument' is parallel to the floor. Now use the folding rule to measure from the floor to the top edge of the spirit level or book. The value you have now determined is your so-called stride length (stride height).
If the calculated value is between two frame sizes, the following applies: For a more agile, sporty ride, choose the smaller bike. For a smoother, touring-oriented ride, choose the larger bike.
Tip :
The frame size refers to the seat tube length from the middle of the bottom bracket shell to the top of the seat tube. For a triathlon bike, choose a frame size that is about 3.5 - 4 cm lower.