New chain = new cluster?

How do you know the chain's gone? Did someone steal it?

If it's worn out, how did you come to that conclusion?

Yes, those answers will give you an idea if you need new rear gears, if that's what you're asking.

Not unless she stretched the chain and it wore on the teeth of the cassette.  Generally that doesn't happen unless you really stretch out your chain.

Assuming regular lubrication, unless the chain was very worn & overused (ran "stretched" more than 1% for >1k mi or so) a road cassette should last for 2 or 3 chains replacements.  A very worn chain accelerates cassette wear, and a new chain on that old worn cassette may not shift well.  But before replacing that cassette make sure the rear derailleur is adjusted properly.

BTW- MTB chains/cassettes wear faster due to dirt/junk from the trails.

Replace a chain as soon as it starts to stretch and you can go through 3-5 before worrying about the more expensive cassette in the back.

There is a cheap tool you can buy to measure wear.

What seems wasteful is replacing a chain after six months unless she's put in an amazing number of miles over that time period...

The only tool I know that measures chain stretch correctly (the shimano tool) is not cheap.

As for understanding chain wear and the parameters involved look here 

Look at the bottom of this page for a listing of tools that show whether a chain is too worn and needs replaced or not.
http://pardo.net/bike/pic/fail-004/000.html

This one is rather inexpensive:
http://www.parktool.com/product/chain-wear-indicator

This one is more comprehensive:
http://www.parktool.com/product/chain-checker

I ended up needing a new chain after a little over 1000 miles on one of my bikes.  It was getting to the point where there was a lot of noise and the shifting wasn't as precise.  I'm fairly good at wiping them down and cleaning/lubricating them after every couple of rides.

You shouldn't need to change cassettes/chain-rings when changing chains. In fact, it's probably good to err on the side of changing the chain to spare wear on cassette/chain rings.

I do use the lightest chain of whatever series (durace/SRAM red) is on the bike so I'm not expecting much durability from them. 

I have a secret chain suggestion .. its 1/4 the price and will last 10x longer..

do you want to know the secret ?

Totally agree, but there are folks on here who insist you need to change your chain every 500 miles, which, when i'm riding seriously, is every three or four weeks.

There is no need to spend tons of money on specific chain stretch tools.  A low end set of calipers works just fine and is much more accurate than what you really need (no need for a Starrett or something extravagant).  And you'll find that you use it for all kinds of other things.  It is a great household tool.

Lou- are you selling 'hot' chains again?   

Sorry for the delay in getting back.

I've done maybe 4,000 km on the chain/cluster. Chain gets cleaned after every coupla rides, full degrease about every two weeks.

I'm getting chain-slip under power. The pedal simply drops out from under me. First time, I landed right on my coccyx. Ended up walking funny for a few days.

Took it to LBS, they measured it up and recommended a new chain and cluster. They may be right, but the cluster sure doesn't look much worn.

Just wanted to check, cos everyone else I've spoken to seems to take it as gospel that if the chain's gone, you gotta through away the cluster too.

Thanks everyone for the input.

Yep. Rear cassette.
Yep. Cleaned regular.
LBS quoted $500 to go up from 7spd to 9spd.




Scored a 3.6 on the 'My butt hurts' index











Cool. Thanks. My lube schedule's been pretty good. I've probably stretched the chain way too far, but the cassette wear doesn't look that bad. I'll have to keep a closer eye on this next time.

It's good to know at least it's not an absolute rule to change both at the same time.




Agreed. My last chain kept me going for 12 months. This one was supposed to be better quality. I guess 4,000km is not too bad, but I'm still a bit surprised by it.





I'm,.... curious..




Damn!

Didn't think of that. Thanks!



Does it help if I say it slower and louder?

not "hot" chains.. but I'll tell you this..

my brother came up with this idea and it works like a charm...

my brother is a bike courier and the beating his bikes take is immeasurable.. so he uses a garage door lifter chain .. I thought it was a great idea, so I use one too.. 2 seasons in and nary a problem.. and thats a lot of cycling.. The chains are designed for 50 x the torque we give them.. so they dont stretch..

you can get the length you need from a Lowe's or Home Depot..

about 2 bux a foot..