formicaman

Guy at LBS told me you have to replace chain and casette at the same time, but how does that work if you have two wheel sets?

Mr. Cranky

Generally speaking the chain will need to be replaced more often than the cassette, so no I don't think it's fair to say they need to replaced at the same time, at least not all the time.

biknbrian

The LBS is not going to make a judgement call. They do not want you coming back after they did work to complain about shifting issues. They say change everything so that they know it will work well. Chain stretch can be measured and I swear that I can see when a cassette is getting worn. The most used gears will look more worn with spaces opened up compared to the others.

oldroads

I agree. You'll go through 3 chains before you need to change a cassette.

DaveSSS 

There is no need to install a new cassette unless a new chain is installed first and the chain skips on one or more of the most-used cogs. How many chains that might take could vary from one, if the chain is left in use for too long, to 4 or more, if the chains are changed too often. Changing chains too often can exceed the cost of a new cassette, and increase your cost per mile.

If you don't get new-chain skip, then a used cassette should not be worn enough to affect shifting.

To really maximize the mileage from both the chains and cassette, alternating the use of 3-4 chains works well. If each chain is used for about half it's life before swithcing to the next one, you'll never get chain skip and each chain can be used beyond the commonly recommended .5% elongation (if desired) since you're not tossing chains in order to avoid new-chain skip.

HillRider

Maybe. If you run the chain and cassette together for several thousand miles like I do, the cassette will always skip with a new chain, particularly in the most used smaller cogs. If you change your chain frequently (the definition of "frequently" will vary with your strength and riding style) a cassette can last for several chains. It's an economic trade-off. Is the cassette expensive enough to justify the cost of three or more chains? Mine aren't.

One way around the two-wheel problem is two chains with master links like KMC, SRAM or Wippermann. Dedicate one chain to each wheel/cassette combination.

pmt

And routinely move the cassettes between wheels. I swap around wheels and cassettes often enough that stuff just randomly wears.

rogerstg

Generally speaking, he is correct for most people because they go too long before changing the chain. If you change the chain at 1/16" wear, you can go through more than one chain per cassette.

For me, I now use a new cassette on the third chain for 10s. That seems to maintain crisp shifting. 9s seems to be less prone to wear issues, but like PMT, I swap those around bikes too much to say for sure.

akansaskid

After 42,000 miles, my 10-sp 105-equipped Roubaix and I have settled into a rhythm: New chain and new rear tire every 4000 miles, new cassette and new front tire every third chain. I couldn't mash even if I wanted to, though. The parts have an easy life.

HillRider

Considering you live in Kansas, I'm not surprised a cassette will tolerate a 4000 mile old chain. Hills? What hills? As long as you don't put a lot of tension on the chain it won't skip even on a fairly well worn cassette and, after several hundred miles, the new chain will even wear to accomidate the old cassette teeth and be even more tolerant.

I would never get away with that.

akansaskid

Perhaps you've heard of our wind, too. Paraphrasing what one-time world-record-holder miler Jim Ryun, a Wichitan, said when asked about hill training: "Half my ride is 'uphill' everyday."

But I agree with your logic. Because I can't/don't mash, my chain/cassette longevity is likely atypical. But not because Kansas presents no opportunities to do so.

Al1943

This is similar to what I do. I can get 4000 to 5000 miles on a good chain before stretching more than 1/16 inch per foot. I get about 3000 miles on a rear tire and a lot more on a front tire. I've never worn a cassette cog enough to skip. I ride plenty of short moderate to steep hills.

fietsbob

keep the chain checking reference gage handy and preemptively replace the chain.
then.. you can get a longer service life out of cassettes.