Even if a two-wheeled friend entered your life a long time ago, you may need to reconsider your usual views on the bicycle and its maintenance. And the thing is this: bicycle manufacturers are continuously working to improve the whole design of bicycles, new materials and the latest technologies have been used to manufacture various components and assemblies.
Bicycles of the new generation have undergone significant changes in comparison with two-wheeled cars of earlier years. Nowadays, nobody can surprise anyone with an onboard computer, shock absorbers, hydraulic brakes, composite frames and wheels. In the manufacture of these components and assemblies used complex technological processes and, as a result, require new knowledge and fresh views on the modern bicycle.
1. Cross-country mountain bike (mountain bike, MTB)
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Best cordless tire inflator have a very strong and, as a rule, fairly light frame, with special geometry. They often do not have a carriage sag, that is, the carriage is not located below the line that connects the axles of the wheels. Accordingly, it follows from this that mountain bikes have an increased ground clearance. For the same purpose, they use a reduced diameter of both leading and driven stars. Due to this decision, when driving over rough terrain, the drive sprockets and connecting rods will not hit the obstacles. In addition, reinforced rims are used, sometimes double or even triple-walled, made of light alloys, often piston-bonded, as well as powerful tires (usually wheels have a diameter of 26 inches). As a rule, the bike is equipped with front and rear derailleurs, the handles are located on the steering wheel. Bicycles in this category have from 18 to 27 gears. They are intended for driving in especially difficult conditions: on stones, mountains, mud, sand, snow. And such a wide range of gears is designed to be able to choose the right one, depending on driving conditions, and a smooth transition between gear ratios.
Also a distinctive feature of mountain bikes is their braking system. It is cantilevered, in contrast to the tick-borne system used on road and road bicycles. The difference lies in the fact that the console brake levers in them are welded to the frame and to the fork. Directly on them brake levers and brake shoes are mounted. Such an “turned out” arrangement gives sufficiently large mud openings, which allows the wheel to rotate freely in the frame and fork in conditions of heavy pollution. But on the other hand, while the progress of the pads is not perpendicular to the rim, and this leads to destructive misalignment as the pads wear. In order to correct the situation in more expensive models, mechanisms are used to ensure parallel pressing of the pads. Shimano, for example, makes parallelogram levers, but Avid uses an arch for this purpose, the hinge in which is in the middle. Such a system looks like a booster, but of course it is not. Nowadays, hydraulically actuated brake mechanisms have increasingly begun to appear, providing smooth, easily dosed, and powerful braking. For the same purposes, and to reduce the intensity of brake wear and release from dependence on dirt, disc brakes were also used. For example, in the Shimano line of models, they are already used on the top four models of a group of eight, although the usual cantilever brakes are preserved.
There is a special design of the front with rear switches with fairly powerful return springs. Moreover, the design of sprockets, both leading and driven, has a different tooth shape and various special steps for chain transitions. And improved chains make it possible to reliably switch speeds in conditions of very heavy pollution and very high loads, both up and down. The reduced diameter of the drive and small driven sprockets contributes to the fact that the range of gears is slightly extended.
Mountain bikes are without shock absorbers in the suspension, come with a front shock absorber, and with two shock absorbers. There are also bicycles equipped with a semi-rigid suspension at the rear.
The most simple mountain bike is not equipped with shock absorbers at all (Rigid). He often has a chrome-molybdenum frame (possibly with a batting). Less often – aluminum, or steel type hi-ten in cheaper models. This subspecies of bicycles is usually equipped with equipment of either a primary or intermediate level. They are quite applicable for trips on the highway and on unpaved roads not strongly broken. Recently, however, this kind of bikes are becoming less common. On a mountain bike, the presence of at least some kind of shock absorber in the front fork becomes the norm.