Aluminum frames are currently the most common. Aluminum is used practically everywhere: in the production of both children's bicycles and top-end downhill (DH) bicycles. This is because modern technologies have made it possible to make them extremely light considering the price, that is, they have the best price-to-weight ratio.
When choosing a bicycle with an aluminum frame, you should pay attention to the type of aluminum and its layering. There are two main types of aluminum: 6061 and 7005. The first is characterized by softness, comfort, and the second - weight and rigidity, which is why it is most often used not in tourism, but in sports. Another important difference between aluminum frames is the layering. The most famous are straight tubes, but they are heavy, so to increase the speed of the bicycle, manufacturers use tube thinning, that is, the walls of the tubes are thinned, and the thickest layer is left only where it is needed. After the more durable aluminum frame is thinned, it may even resemble aluminum foil, but this does not affect safety.
Until recently, carbon fiber frames were only used in road and mountain bike competitions due to their low weight, high speed and stiffness, but the situation is gradually changing and carbon fiber is becoming increasingly popular among amateurs. The main reason is that the weight of the aluminum frame can no longer keep up with the extremely low weight of the carbon fiber frame. Despite its low weight, the carbon fiber frame can be very durable.
Steel frames are best suited if you plan to go on long tourist trips or mountain tours with the bike. The main advantage of such a frame is that it is easy to weld. The biggest disadvantage is its high weight.
