The best way how to replace a cassette on a bike, if the chain starts to jump over the modes, it is worth taking a good look at the sprockets – are they not excessively worn? If instead of pointed teeth you see a strongly worn “shark fins”, it is an obvious sign that it’s time to change the cassette/freewheel. And how to know if there is a cassette or freewheel on the bike? And how do they differ? The main difference is assembly.
The cassette on a bike
The cassette is applied to the hub and then tightened with a nut. The freewheel is screwed onto the hub. If you have 9 years or more, you have a cassette of 99.99%. If 6-7 sprockets is most likely a freewheel. If 8 sprockets – it can be different. But in any case – it’s best to check it out well. In the pictures below I will show you freewheel bike part and cassette.
The chain begins to pull out with time. The spaces between the cells are getting bigger, so the chain starts to rub teeth in the cassette and the crank. If you change the chain early enough, the cassette/freewheel has a chance at a longer life. If you drive on the pulled chain for too long, you will also need to replace the cassette with the chain. You will read about the chain wear and how to check this entry.
Cartridge for a longer time
There are three driving schools. One tells you to check the chain pull and when it reaches 0.75%, replace it with a new one. In this way, the sprockets will be slower to wipe off. The second school talks about buying three chains and exchanging them in rotation every 300-400 kilometers, assuming each time the least drawn from a given three. Thanks to this, a solid chain will work on one cartridge for a longer time, which should prolong its operation. The third school, on the other hand, tells you to ride on one chain and the cassette until the chain pulls out enough that it will jump and make a noise, and the clasp will peel off. Then we exchange the best way how to replace a cassette on a bike and chain (and sometimes the rack/gears in the crank). How to replace the rear derailleur cable in your bike?
I basically recommend the first method; it is low absorbing and quite efficient. In the picture above I wanted to show you two gears from the cassette and freewheel bike part. The one on the left is used, maybe still not tortured to death, but the best times are long gone. Theoretically, with a little bit of intrigue, you can resuscitate it with a file. On the right side, there is a brand new sprocket. If you want to take a close look at the differences between them, click on the picture to enlarge. It is clear that the teeth used in the rack were sharpened and their upper edges shortened. The pulled chain still worked decently on her, but with the new one she could not get along anymore.
An appropriate key for the cassette
In the picture above, you see a cassette. At the very end, it has a cap and tabs for inserting the key. To remove the cassette you will need the appropriate key for the cassette (shown in the picture below) and a back, i.e. a piece of chain attached to the handle used to hold the cassette. The back can be done alone from the old chain. I used to unscrew a cassette without a bolt, fastening the cassette with spokes to the spokes – but I definitely do not recommend this method because it puts a lot of stress on the spokes.
Having all the tools prepared, hold the cassette modes (preferably catch at least the third from the bottom), insert the key into the cassette nut and use a flat wrench to start unscrewing the nut (counter-clockwise).
When the nut goes downslide the gears of the hub. The cassette can form a single, undetectable whole, but it can also be in several parts – so that you can replace only one or two of the most worn rackets for new ones.
When installing the cassette, first of all how to replace a cassette on a bike, clean the hub and the cassette itself, if you mount the same. Also, pay attention to correct installation. Typically, each sprocket has one of the mounting tabs wider or narrower than the others. They will help you in the correct set of modes. Finally, replace the nut and use a wrench to tighten it. The back will not be necessary at this stage, but you can still hold the cassette in order not to expose it to unnecessary strain.
Freewheel bike part
In above you can see a freewheel bike part and its activity. It has no nut that can be removed, it is unscrewed completely. In his case, it will be a little easier. Very often just the key to the cassettes shown in the picture above is sufficient. But a lot depends on the key itself. However, it is best to buy a special key for freewheels, which looks very similar (it is a bit longer). Then it will be 100% sure that it will fit. Back is not needed. Just insert the key and counter-clockwise – unscrew. If it goes reluctantly, it is worth using a vise. Insert the key into the vise, put a circle on it and start to unscrew. It should go a lot easier.
The assembly of the freewheel is equally simple. Before assembly, of course, clean the hub and the freewheel itself, and then screw it clockwise on the hub. Make sure that it wriggles in evenly. Then tighten it with the key. You do not have to do it forcefully, the freewheel has this interesting “function” that it tightens itself. All you need to do is put a bicycle wheel on and ride the piece at a calm pace. The freewheel will tighten itself with sufficient force.