[Closed] Chain life query

Till the checker says change it.
Miles/KM's are roadie measurements

Mountain bikes pick up all sorts and have vastly different lives to one another so pinning some milage value on is a bit pointless.

Ignore the checker, keep on running. A chain wears components whether worn or not. The only reason for an early change is that a new chain won't mesh with a worn cassette. You can throw away a perfectly good chain to ensure you have a shiny chain and then the next chain or two you'll need a new cassette anyway. Or keep the chain on and you'll be changing the cassette much further down the line when it's all actually worn out, so long as you keep worn with worn. The risk is if you destroy the chain and need a new one you'll need a new cassette, but you with quick links you shouldn't have a chain destroyed so much you can't still use it for a long time.

Swap the chain.

The worn chain isn't just wearing the cassette, it's taking the chainrings and jockey wheels with it, too. Common sense says that the timely replacement of the chain means two chains before the cassette needs swapping and you'll probably only need a middle chainring instead of the set.

If I run a drivetrain until it skips on an MTB, I reckon maybe 1000 miles out of chain and cassette.
On a road bike 2-3 times that.
I've never bothered changing chains TBH. I just clear up secondhand sets of new chainrings off here and eBay for £20-£30 a set then buy the cheapest chain and cassette I can lay my hands on, then replace the lot together.
That generally means middle ring with chain and cassette, then all 2/3 rings with chain and cassette the next time.
It's never cost me more than £50 to do the whole shebang with 9sp stuff. 🙂

I don't know what Kenny is trying to say, but many people change the chain only at 0.75% worn as a new chain will still mesh on the cassette. You can even get into rotating part worn chains to get the most out of the cassette.

This all makes sense as the cassette is usually way more expensive than the chain.

9 spd chains are dirt cheap, change the chain as soon as it is showing wear (ie .75).

You may even get 3 chains to one cassette/rings etc this way

I use a chain checker. Once the checker says it's buggered, I think measure with a steel rule and bin it when it's "stretched" 0.5% over as much distance as possible.

This means I get about 4 chains per cassette and two cassettes per chainset.

cynic-al - Member
I don't know what Kenny is trying to say, but many people change the chain only at 0.75% worn as a new chain will still mesh on the cassette.

Many people do it because if done early enough a new chain won't skip on the part worn cassette, but it's false economy. All you're doing is spending more money on chains and then 2nd or 3rd chain you need a new cassette anyway.

Run one chain to death and the cassette will last just as long, and probably much longer.

The only reasons for doing the early chain replace I can see is because someone long ago (was it Sheldon B?) insisted you have to and also Park Tools makes a lot of money out of selling chain checkers. Other thing is in the past if you snapped a chain you'd end up replacing it and the new chain won't work on old cassette, but with quick/missing links a snapped chain is good to go (plus if you buy KMC it won't snap anyway).

There's no logic to it otherwise. As I say, components wear whether the chain is worn or not.

And I speak from experience having tested both methods and on two different bikes. I used to believe for years in the Park Tools hype, and was spending loads of money on chains and throwing away cassettes early because they only cope with 2 or 3 new chains. Now I run it all to death and the stuff just goes on and on way longer. I now chuck away components when they are actually dead.

Personaly I use a chain and cassette as a pair till they slip then just replace both.
Over the years it's suited me and saves dripping feeding money.
But then I don't have silly priced xx1 cassette