Surprised by advice

[Steve H]

I took my bike in for a service this week. It has done a couple of thousand miles over the first 10 months of it's life. When the guy was looking at it he measured the chain length and said it was about 70% worn and I should change it after another few hundred miles. All sounded sensible, but he then said it was best to change the cassette at the same time. I had always thought that cassettes lasted a lot longer than chains so I double checked with him. He said, yes always change them at the same time.

Is this common advice or have I just come across an unusual view?

Not sure if it makes a difference to the answer - the cassette is a Shimano 105 10 speed 11-28.

 

[ASC1951]

Cassettes last longer than chains, but not hugely so, particularly since a badly worn chain will finish off a cassette quite quickly.

I get through two chains for every cassette i.e about 6000 miles. But
- I use better quality chains than the ones the bike came with;
- I keep my chains in reasonable nick (the Mickle method);
- I use a chain wear indicator http://www.chainreactioncycles.com/Models.aspx?ModelID=5784 and I swap chains before they are at the limit.

If it was me, I would buy a chain gauge, check the chain and replace it fairly soon but leave the cassette this time. I used to use Sedis chains at £20-ish, but most shops prefer to stock Shimano Hyperglide these days which IME aren't particularly good value for money; more hype than hyper.

 

[Jimmy Doug]

If you ride with a worn chain, you can damage the cassette. However, I don't believe you need to change the cassette after every chain change - cassettes take longer to wear. I doubt very much that you have done enough miles to warrant changing the cassette right now.

 

[byegad]

+1 for regular chain measurement, I now use a Park Tools Go/No go gauge. replacing the chain as soon as the 0.75% side fits I get three chains to a cassette and I usually replace the middle chainring at the same time as the cassette, it gets more use than any other part of the drive train.

Let the chain get to 1% worn and you need a cassette and maybe chainring(s) as well as the new chain.

 

[Red Light]

You only need to replace the cassette if the chain wear has gone too far. Take a 12 inch rule and put it against the top run of the chain while putting light pressure on a pedal. If the distance between the rivets is more than 12" and 1/16th the chain needs replacing but if its gone to 12" and 1/8th you probably need to change the cassette too. But the simple way to do it is to replace the chain and see if it works. If the cassette is too worn, the chain will slip in some gears. If it doesn't you're fine and have saved some money.

Sheldon Brown explains it all

 

[mickle]

It's a myth that you should change the cassette and the chain at the same time - one propagated by the dishonest or ignorant. I've read it as advice given my idiot cycle journalists.

What wears out cassettes is 'stretched' chains - so there is a point at which a very old chain will have damaged your cassette so badly that it requires replacement. Replacing the chain regularly after very short periods of use so your cassette never encounters a worn chain will result in cassettes (and chainrings) which last indefinitely.

The trick is to find the performance/cost/durability balance between a new chain every week and running your transmission into the ground. The thing to remember is that chains are consumables. Sprockets and chainrings don't need to be.

The way I do it is to replace my chains before they show significant signs of wear (good chain maintenance has a big influence on durability). I am currently using a chainring which was purchased in 1995.

 

[ColinJ]

I agree with the advice above.

You can wear your cassette out in 2,000 miles if you don't clean the chain and cassette often enough and ride your bike in wet, mucky conditions, but I usually get through about 3 chains per cassette.

If you leave the old cassette on and it is too worn, the new chain will slip under pressure e.g. on the steep climbs you tackle on my forum rides!

I leave cassettes alone until a new chain slips.

 

[actonblue]

After 2000 miles I doubt if you would have worn the cassette especially if the chain is 70% worn.
I get about 3 chains to the cassette.
Rohloff do a gauge for checking cassettes. Your best bet is to change the chain yourself and if it slips you need to change the cassette but I doubt if you will need to do this.

 

[Steve H]

Thanks all. Thought the initial advice was strange. I'll change the chain on it's own shortly and then consider the cassette and chain next time round.

 

[Fiona N]

Another trick is to buy two or three chains when you get a cassette and alternate them so that the wear is evened out and the cassette doesn't have problems which arise from using a new chain on worn sprockets.

By the time all three chains are worn, you might need a new cassette.

 

[byegad]

Thanks all. Thought the initial advice was strange. I'll change the chain on it's own shortly and then consider the cassette and chain next time round.

IF you get the new chain skipping then where it skips, front or back needs replacing too. At the back you just replace the cassette. If it skips up front just the ring(s) on which it skips.

 

[YahudaMoon]

They say 3 chains per cassette though cassettes can last forever depending on what type you have and if you change your chain before any damage is done to the mechanics.

 

[GrahamG]

10 speed is a ball ache - if your chain has begun to wear (and therefore your cassette too to some degree) you'll never get away with just a new chain on a 10 speed cassette as it will skip somewhere. Changing chain regularly as suggested will work, especially rotating 2-3 chains so that they all wear evenly, but do bear in mind that it's really the very tiny minority of people who will do this so the LBS man isn't bullshitting you at all, he's just talking about what is necessary for 99% of his customers.

Personally, I've always just made sure that it's reasonably clean and well lubed - combined with a fairly reasonable cadence and not using extreme chainline - and still got ~3000 miles out of a single 10 speed chain/cassette. Of course due to increased mileage (audaxing!), I've since upgraded to 8 speed so I'm heading for 5 figure mileage durability

 

[Jimmy Doug]

Interesting. I was thinking of changing to 10 speed, but I don't think I'll bother now.

 

[GrahamG]

Great for racing or just for wanting the best performance in shifting terms (YMMV but I found 10 speed really, really crisp - both campag and shimano - compared to the 8/9 I run), but no other reason to change other than if you end up totally stumped for spares/parts.... but that tends to be more of a campag problem..