Calculate frame size
Choosing the right frame size is based on the leg length of the cyclist.
To determine your leg length, you need ideally a folding rule and a water-level.
With legs together make up straight and pull the water balance between the legs upwards. The best s can help you.
Now read the measurement from the floor to the top of the level with the folding rule.
Note: The typical leg lengths are for
men: leg length = 0.483 * total body height in cm
women: leg length = 0.503 * total body height in cm
(Women have, on average, longer legs than men of the same size!)
More information on this topic can be found in the book by Michael Gressmann: Fahrradphysik und Biomechanik