The most important for comfortable cycling is the correct size and geometry of the frame.

The DEMA Company marks the sizes of their bicycle frames as S, M, L, and XL, or in inches. Sizes of road bicycles are listed in millimeters. There are no precise rules regarding correct frame sizes nowadays, the result of various variations of frame builds. That is why the customer should not rely solely on frame height or saddle tube height when choosing a bicycle, since length and overall seat height change along with frame height.