Does new chain = new cassette?

Depends on how bad it's worn. I'll get 3000+ miles out of a cassette on a road bike, far less on MTB.

so the shop told you that you should spend another $100, presumably there. Big surprise. I bet they just happened to only have Dura/ace cassettes in stock too. This piece of advice dates back to when cassettes cost $20 or so, and there really wasn't a compelling reason to try to extend their life. Ironic, because all the employees at every shop I frequent were in diapers when that was true.

the matching story is that as the chain wears, the distance between the pins increases (often referred to as stretch, though this is a misnomer). As the cassette wears, the gaps between teeth increase. What can happen is they wear together, then when you put a new chain, with the correct pitch, it doesn't want to stay on the worn cog. It's really easy to see if this is the case - just ride with the new chain. Put the RD in the gears you use most, if it doesn't skip in the first couple miles, it isn't going to. The shop should have done this as part of the tune up, then they would know if the cassette was worn, rather than just guessing.

so in short: no, new chain does not equal new cassette. Worn out cassette = new cassette.

No way. If you clean well (the bike, not you) and lube well (again) then you should go thru a number of chains vs. cassettes. Also, changing the chain every year while cleaning and staying lubed will keep the cassette in good shape. I know many that have 8-10k miles on the same cassette.

Usually yes, but like the previous guy said, if you maintain the cassette it really should outlast the chain.

My rule is 2 chains=new cassette... as long as you keep after the drive train (cleaning at least once a week, or after any ride that's been especially dirty, ex. after rain), you won't wear out the cassette that fast. It also helps that I usually take the cassette off when I clean it and let it soak in degreaser and then give it a thorough scrubbing.

The Chorus cassettes seems to outlast the Record and when I rode Shimano, the Ultregra lasted longer than the Dura-Ace....

All depends on how far gone the chain is and the "stretch" involved. They have a tool at LBS that measures this stretch. New chain is about .20 spacing and extreme stretch is around .80. Once you ride on a chain at the higher end of this # for more than a month or so, the cassette has good chance of damage and will need to be replaced.

Cheaper to get $50 new chain every year or so than go too long and make both changes. They may very well be right.

Good luck.

thanks for the info on the chains

I've replaced my chain a few times on my bike but never the cassette.  The cassette probably has upwards of 7-8K on it.  I had my bike in the shop yesterday and they said my current chain has stretched and gave me the same "you should swap out the cassette with the chain" thing.  I only agreed to swap the cassette because it is original equipment that I know has 7-8K on it and my bike has been skipping for weeks so as another poster said I have probably now hurt the cassette by riding around with a stretched chain.  I definitely believe the cassette should last longer than the chain as long as you switch the chains before they stretch too much.

Oddly enough, I had a tuneup just a few months ago and they said my chain was fine.  And the bike shop I was at yesterday swears up and down that there is NO WAY my chain stretched that much in a few months.  Can't figure out who is wrong!

I go through two chains a season on my mountain bike (I do 15+ races).  I only change my cassette once a year.   MTB components take a pounding and see rain, mud, snow, dust and dirt.  On my road bike, a chain will last a year and cassettee maybe longer.  I am EXTREMELY anal about cleaning my stuff too.