While cleaning my chain and cassette I discovered there are two and a half teeth missing from a couple of sprockets on the cassette. I probably should have noticed earlier but I've been a bit naughty with my maintenance recently.

Anyway, the bike is a Bianchi Via Nirone 7 with Mirage bits, and the cassette is a Fac Michelin PRIMATO 12/25. I've never worked on the cassette before, so perhaps someone can help me out here? Can I just swap out the cassette, or would it be better to change the broken sprockets? I've had the bike about 18 months, so the teeth are a bit worn on all the sprockets. I remember hearing something about the chain, chainset and cassette wearing together - if so, will I need to change all these parts at once? If I get a new cassette, will any of the same type work okay, or should I stick with the same make/model etc?

Thanks for any replies.

You be best to replace the cassette and the chain togather.

Thanks for the reply.

You may try replacing the cassette without replacing the chain, but check your chain carefully for damaged links and stretch. A new chain can be used on an older cassette with no negative consequences, but the reverse isn't true.

Unless your chain is relatively new and in excellent condition it might make financial sense to replace it also. If it's worn (stretched) beyond about 20-30% of it's life (more than 1/64" it'll rapidly wear the cassette to it's own relative age, costing you valuable cassette life.

Comparing the cost of that wasted cassette life to the cost of replacing a chain, it's often cheaper to spend the extra $$$ now. Not to mention that it'll run smoother too.