Cassettes and ratchets for beginners
The cassette is made up of stars (all or individual, depending on the design) attached to the fastener with slots, and the bushing body has ledges of the appropriate configuration (slots), which ensures the correct installation of the cassette. The ratchet is hidden inside the drum.
The cassette drum mechanism has several advantages:
- More stars from 8 to 12 on modern models
- Less rolling resistance than ratchet
- Less weight
- It is easier to remove
- More ratchet mileage
Ratchet – ratchet mechanism with threaded or spline mounting on the bushing, ratchet is located outside.
Shortcomings of the ratchet:
- The number of stars ranges from 5 to 7.
- Heavy load on the thin axis of the bushing, which causes them to bend.
- Screws in with a lot of torque, it looks like this: as you rotate the pedals, the ratchet is screwed into the thread of the bushing every time, stronger and stronger. Sometimes it’s almost impossible to unscrew the ratchet later!
Types of tapes
All cassettes are slot-mounted and interchangeable. Let’s say that you can replace an 8-sk cassette with an 11-sk cassette with a switch and a manlet without having to change the back sleeve. If you look at the cassettes in the profile, you will see the cassettes almost the same width, although the number of stars is different. In order to leave the same width of the cassette, the distance between the stars is reduced.
The stars are connected to each other:
- The stars are pegged together and the stars are separated by spacers. These cassettes are mounted on steel drum hubs or simply on inexpensive bicycles. The advantage is that they can be disassembled to zero by removing the pins from the grooves, but they should not be placed on lightweight aluminum drums, as high torsional loads (especially large stars) damage the drum.
- On a spider – the stars are dressed on the so called single spider, which comes in the form of a ladder.
The torsional force is transmitted not only to one star, but to the entire block of stars dressed on a spider. This way, the load on the drum is reduced. These tapes are also lighter. You can change the last 2 or 3 stars on a spider. On 2 or 3 spiders – stars dressed on 2 separate spiders.
This is done so that the produced stars can be replaced individually by blocks of stars, rather than changing the whole cassette. If worn, one of the spider blocks or the lower 2-3 stars can be replaced separately. Depending on the level of the cassette.
Whole milled cassettes – the whole unit is made as one part.
Dressed on the slits on the left side of the drum and fastened to the lower star. The cassette is at the same time the slot under the drum. Among analogues, it is the most expensive option. The complex manufacturing process gives a high price, in addition, you need a special SRAM-XD drum per sleeve.
The bike cassette can be dialed from a variety of stars:
- 7 – can be seen on old bicycles, the same year as the ratchet copies.
- 8-10 are the most common bikes used today on many bikes, from mountain to highway.
- 11 are made by Campagnolo. You can put them only on the bushings of this company.
The number of stars and their range are indicated in the labeling of the cassette. For example, the inscription “11-36T, 10 speed” means that the smallest star has 11 teeth, the largest – 36, and a total of 10 of them.