Кассеты на велосипед
Bicycle cassettes, this is an important part of the transmission, cassette stars are driven, driven by the system stars (leading). There are two fundamentally different structures in the middle of the set of rear sprockets on a bicycle: a cassette and a freewheel (aka a ratchet). They differ from each other in the type of attachment to the bushing, the set and number of stars and the alloy material.
These two components are not interchangeable and are selected, first of all, for the rear wheel hub, and then for the number of speeds, shifters, shifters, chain, etc.
The freeride (ratchet) is an older mechanism currently used for city bikes and budget mountain bikes. It is a one-piece, non-collapsible structure with great weight. Most often they have a set of 6-7 stars. The number of teeth on the smallest 14T, on the largest 28T (for six) and 34T (for seven). On the sleeve ratchet is fastened by screwing onto the thread (ratchet mechanism). The ratchet is removed using a special ratchet remover wrench. After wear, the stars are unscrewed and completely replaced.
The cassette is a more modern structure, which has more varieties (, for mountain bikes), most often the number of stars is 8-10, but there are 7 and 11. The cassette sleeve has a slotted drum, the cassette also has corresponding grooves, so the method of fastening the cassette on the cassette sleeve - slotted. The ratchet mechanism itself with dogs is in the drum. The cassette is fastened with a locking ring. To remove the cassette, a different key is required - a cassette remover that matches the slots. The smallest sprocket of the cassette has 11-12 teeth, which increases the gear ratio and, other things being equal, allows you to develop a higher speed than on a bicycle where the ratchet is installed.
Cassette and ratchet bushings have different bearing arrangements. In a cassette, the right bearing is located closer to the edge, so the axle is less susceptible to bending or breaking from stress. The technology has been patented by Shimano. In ratchet bushing the bearings are located closer to the center, so there is a large load on axis.
Sets of stars on cassettes (11-28T, 11-36T) for mtb and transitional class cassettes (11-27T) allow you to select a load level at which even a heavy cyclist can ride a steep incline.
Cassettes are made of different alloys (steel, aluminum, titanium), but even the simplest steel nickel-plated or chrome-plated cassettes will be more durable than ratchets. Most of the cassettes found in our country are collapsible (individual stars are interconnected by screws or rivets) or on a spider (a spider is a structure made of light-alloy material, to which the stars are attached). Therefore, with a cassette, it is possible to replace the worn out parts of the cassette, and not the entire mechanism.
Cassettes have long proven their advantages for both comfortable loading and longer service life. If you like to ride and your bike is exposed to decent loads, you should opt for cassette ... This, ultimately, will allow you to save materially and will not bring unpleasant surprises in the form of breakdowns along the way.