With the development of the times, the materials for making frames have expanded from chrome-molybdenum steel in the 20th century to aluminum alloys, carbon fiber and titanium alloys in the 21st century. There are also a variety of protective paints sprayed on the frames.
As far as frame classification goes, the standards vary. Taking BMC as an example, according to the different usage scenarios, road bikes are divided into comprehensive frames (SLR), aerodynamic frames (TMR), endurance frames (RM) and off-road frames (CX). Of course, it can also be divided into hard tail frames and soft tail frames.
Just like shopping for clothes and shoes, frames are divided into sizes. The standards for road bikes and mountain bikes are different: the former is generally expressed in terms of the length of the riser, in centimeters (cm) or millimeters (mm); the latter is generally expressed in inches, such as 16 inches, 16.5 inches, and 17 inches. Sometimes some frames are marked by code numbers such as S, M, L, etc. At this time, you need to go to the official website of the brand or the dealer to check the corresponding length unit.
It should be noted that the dimensions of different brands of frames are different. Even if the dimensions marked on the frame are the same, the actual size may vary.