Replacing a bike cassette is simple enough, but does require a few specialist tools. You will need a cassette key of the right type and a chain-whip. You will recover the cost of the tools by carrying out the task by yourself. Sometimes a cassette seize on to the hub over time. You can gain extra leverage by either extending the length of your spanner with a metal pipe, or by putting the cassette key in a vice and using the turning moment of the wheel.
This is a long guide, so you can choose to either watch the entire video above, or follow it in smaller chunks by clicking on the individual steps below.
Steps to Replace A Bike Cassette:
A freewheel is a ratchet mechanism mounted on the rear hub which allows the chain to drive the wheel forwards via a cog but when the wheels move faster than the chain the cog is not driven round by the wheel. A freewheel allows a rider to rest their legs while the bike is moving forward.