When to replace a cassette?

Question for the mechanically inclined:

Is there a rule of thumb for when you should replace your cassette? I am having more and more ‘lazy’ shifting problems on my road bike for which derailleur adjustments are becoming less effective. I’m wondering if it’s time for a fresh one. I’m not the kind of person that can eyeball the wear/tear on the cog rings.

For reference, the cassette in question is a SRAM Red 11-32t, it’s 4 years old and has ~18,000 miles / 29,000 km on it.

Thanks in advance.

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29k? Honestly it probably needed to be changed over 10k km’s ago.

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When you replace the chain if it’s stretched. Or every two chains.

If it’s skipping and the chain is new. Cassette time!

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I usually buy a chain and a cassette. If the new chain doesn’t skip on the old cassette I can save it for the next time. If it does the new cassette is needed. I think the most I’ve had out of a chain not needing a new cassette is (4,500miles, circa 7,200km) so that cassette might have been on there 9,000 miles (14,500km).

I was told by the lbs it should about every 1500km, I find that a bit too often, so change it every 3000km to 5000km or so. I do change the chain more often, about every 2000km and every time I can notice the difference.

Just to add, I just replaced my front chainring after about 25000km.

You can tell by looking at the teeth, they should be flat
If they start to become like shark teeth you are too late. ( Also do not forget about your jockey wheels )

That’s insane. I would be replacing cassettes eight times a year. As it stands I can get a whole year on two chains, let alone cassettes.

This is a condition-based maintenance item like replacing chains. Don’t do it by some thumbrule distance. Inspect the cassette. If you see “shark teeth”, replace the cassette. If you use a proper length chain, take care of your drivetrain, and replace your chain at 0.5% wear (11spd), cassettes should last much longer.

It also depends on what type of cassette you’re using. DuraAce is going to last longer than Tiagra. That’s why it’s important to know what you’re looking for.

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Like Kurt says, you change it when it needs to be. I usually get 10,000km+ from a chain, probably 30,000km or so from a cassette and around 50,000km from an outer chainring.

FWIW I ride 12,000km+ per year in the UK, all year round, including lots of gritty base miles in the middle of winter. I use dura ace chains, I don’t know if they are more durable than others but they work well for me.

Replacing parts based on a short, pre defined distance would be a quick way to spend a lot of money

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Road bikes used in reasonably good conditions, probably 10k+ miles.
Gravel/Mountain bike is more based on visual inspection given how variable the riding conditions can be.

This assumes you’re regularly replacing chains when worn and keeping them in good conditions. Silca even suggests chains can last 10k miles if you’re waxing and taking good care of them.

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I am presently well over 3000 miles on two Ultegra chains and don’t appear all that close to .5% wear. Last two chains went 4K each and I changed them before starting the new season. They might’ve gone longer. I use MSW, and agree that waxing done properly is not only faster but preserves key drivetrain components longer. I surmise it’s because the whole operation is just cleaner, so things wear less than oil based lubes that get greasy and dirty.

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It’s going to depend on your wattage and how many hours you ride. I run through a chain about every 3 months riding 150-200miles per week (8-10hpw). If you replace the chain before it’s stretched (<0.5 for 11spd, <0.75 10spd) then you can run a few chains through it.

You are technically supposed to change it when you change a chain because they wear together, but I have almost never had any issues (running shimano 105 & ultegra).

Personally, I change the chain right at 0.5 (the limit) and will change the cassette one a year or two. Never have any real issues.

Skipping can be a lot of things: misaligned rear derailleur hanger, poorly adjusted rear derailleur, worn cassette, internally frayed shifter cable, worn chainrings. Bottom line is that if your rear mech is properly adjusted, there should be little need to mess with it throughout the life of a chain (almost none if your shifter cable is properly pre-stretched). You have some other issue with your setup.

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Sounds like me. Lazy shifting the last few weeks. I checked the chain and realized it’s time to replace. New chain just arrived today and it’s better, but still seems to hang up on 1 or 2 shifts in certain directions. Gonna take it out and confirm – I always find it shifts a little different when I’m actually riding it than when it’s on the stand.

I also find it hard to eyeball wear on cassettes (unless it’s obscenely bad), but checking when I last ordered the 11-32 for it says it’s 4 years old. I think I’m just going to pull the trigger on a new cassette – it has seen a lot of miles.

Another prime culprit is the shift cable/housing… too much drag in there causes problems, particularly on upshifts in my experience.

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Sadly this is not true. The largest cogs on a Dura-ace cassette are made out of titanium, they are quite a bit softer and less durable than the steel cogs used on lower tier cassettes. A well maintained chain can outlast a Dura-ace cassette.

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You are correct. I was imprecise in that part. :man_facepalming:

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I’m shocked by how frequently some of you change cassettes! Wow!

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Why change something that works?

Like said above - check the chain and replace if its stretched. If the new chain is skipping on the old cassette, change the cassette too.

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Because if you don’t everything in your drive train will fail at once in what will be a costly way. Change the chain every so often will usually you the cost of having to replace the cassette and when you do need to replace the cassette it’ll save you the cost of new chainrings. I am not disciplined enough but some folk check their chain often with a Park chain measurer and save their self a fortune.

I’ve gone through one cassette and two chains since 2017 (doing well over 10k km each year) , waxing is a certified winner! A fair bit of that time I was using home brew topped up with squirt, blue using MSW topped up with super secret so should get even better life out of parts :+1:

Oh and to actually answer the question, I have a cassette checker: Rohloff HG Check Sprocket Wear Indicator

Generally don’t change until a new chain slips on the old cassette though. You can also measure the distance between the teeth on the most used cogs for a clue

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Oh, thats good. Never thought of that, but makes sense!

People are still calling chain wear “stretch”??? Steel chains wear, they don’t stretch. I don’t know how that term started but it really needs to go away.
Cassettes and chains wear at different rates and some cassettes do last longer, but if you leave a worn chain on too long it will accelerate the wear on the cassette. Ti is harder than steel so I’m not sure why some of you guys with Ti cogs are getting faster wear on them - doesn’t make sense. Try cutting or drilling Ti with HSS then explain to me why your Ti cogs are wearing faster than steel.
So when to replace? When they are worn enough that you notice it with a new chain or one worn less than 0.5%. I think this is a better method of determining when to replace than at some arbitrary mileage. Chain load, conditions, lube and material all factor in on time to wear.
Wes

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