How to tell if modern cassette is worn out?

Old cassettes were easy to inspect - just look for 'sharks teeth' . Now I am looking at my Linkglide 11 speed cassette with 3000 miles on it and the tooth profile is all over the place!
The lower gears all have a symmetrical trough that is way wider than a chain roller so you cannot check for a tight fit. The smallest cog has pointy shark teeth by design.
So how can I check (measure?) for wear on a particular cog or do I just have to wait until a new chain jumps off a cog under load?

Mine started jumping when i fitted a new chain at .5. Cant remember how many chains i got through.
Its always the 13t as thats my main gear. Replacement cogs can be purchased but they were about £15. The entire 10 speed cassette is only £47.

To my experience it is hard to tell visually when cassette is worn. Generally on e-bikes when chain is worn, cassette usually won't accept a new chain and skips.
Few things to keep in mind:
- A cassette by itself won't wear that much
- Cassette wears mainly due to chain wear
- Good chain maintenance extends chain life, so it all depends on that

Understanding this, there's some simple ways to extend total drivetrain longevity:
- Run 2-3-4 chains on rotation (never, ever wear a chain, and then start with a new one, the cassette by than has already followed the chains wear pattern, and the new chain+cassette will wear quicker because the cassette don't match)
- Rotate every +- 500kms, when all chains are at 0.00mm wear.
- When first chain starts showing wear, remove this one from the rotation
- Allow other chains to catch up to same wear as first chain
- Maintain this rotation strategy and swap based on measured wear, mount the best chain and let it's wear catch up with the next in line (use a caliber, or KMC digital checker)
- Use a proven top wax and stick to maintenance intervals (see ZFC)
This has already saved me hundreds of €€. In the last 2 years, by trial, I increased drivetrain longevity by 4.5x on 1 of my Ebikes. Actually over 4.5, since I sold the bike at that stage, with average chains worn 0.45%, so far more kms to go. (1st drivetrain was 1x chain, weekly degrease and relube with Squirt and made it 2.500kms, 2nd drivetrain was 2x chains on rotation and weekly rewax with Silca hot wax, done total 11.250kms).

My advice, run multiple chains on rotation, wear it all out to the bone, then replace everything (including chainring). Lowest cost/km.

I agree 100% with your first paragraph.

Following that regime, I'm not surprised that you get results.

I can only comment that I have never ever done 11,250 kms (7030 miles) on a single bike. So whilst I can see that you get the benefits, I would have to run fewer chains than you for me to see a benefit rather than the person I'm selling to. I once tried three chains, but sold the bike before I could even get a hint that it was working!

I have discovered that if I buy top of the range chains (nothing less than XT or similar), then on 11 and 12 -speed drivetrains I do very well indeed using one chain. I have never bothered doing a cost analysis of using one high spec chain vs several lower spec ones. If I did. I'd have to cost in my own effort, because basically I'm a lazy sod!

billium said:

Old cassettes were easy to inspect - just look for 'sharks teeth' . Now I am looking at my Linkglide 11 speed cassette with 3000 miles on it and the tooth profile is all over the place!
The lower gears all have a symmetrical trough that is way wider than a chain roller so you cannot check for a tight fit. The smallest cog has pointy shark teeth by design.
So how can I check (measure?) for wear on a particular cog or do I just have to wait until a new chain jumps off a cog under load?

Click to expand...

Your shifting will go to hell. You will not be able to successfully adjust it with the barrel adjuster.

CaptChip said:

Your shifting will go to hell. You will not be able to successfully adjust it with the barrel adjuster.

Click to expand...

Yes he will, derailleur adjustment has nothing to do with cassette wear, those are 2 different things. What you probably mean to say is due to cassette wear, the contact point where the tooth falls into the new chain’s gap is at a point where it won’t match. Which leads to bad shifting behavior. It will shift. But takes longer and not smooth.

billium said:

So how can I check (measure?) for wear on a particular cog

Click to expand...

You can't.

You can replace the chain and then see how everything runs. But when you put a new parts with old, wear is accelerated.

Considering you already have 3000 miles on the drivetrain, you might better off just running everything until shifting begins to degrade, and then just replace the chain, cassette, and chainring all at the same time.

I buy the cogs in bulk, and have cassettes and chains on hand. I formulate my own lube. I replace both 11 and 13T cogs the minute there is a skip. I replace the chain when it is at .5 on the wear gauge. I replace the monoblock cassette every third time I need to replace the 11 and 13 cogs.

I'm currently at 11,143km on my Trek Rail. It's had 3 chains so far and I replaced the cassette at about 10000kms as the chain was jumping under load.
I wipe the chain down the night before my ride and put a good amount of 'Rock n Roll Gold' on it, then lightly spin the chain through a cloth so the wax doesn't clog the cassette too quickly. I couldn't be arsed stuffing about with multiple chains and ratios of change of sprockets to cassette. Keep the chain lubed and clean and you will get 5000kms out of a chain and double that out of the cassette without too much trouble.

Im running GX Eagle AXS on my Scott Patron and am now due for a cassette replacement. Have run 3 chains over 4,100km. Third chain has wear but cassette plus a new chain isnt working. I plan to just use this old chain until shifting becomes an issue (shifting great right now) and then put on new cassette and new chain. I do keep drive train pretty clean and lube every week (approx 100km)

billium said:

Old cassettes were easy to inspect - just look for 'sharks teeth' . Now I am looking at my Linkglide 11 speed cassette with 3000 miles on it and the tooth profile is all over the place!
The lower gears all have a symmetrical trough that is way wider than a chain roller so you cannot check for a tight fit. The smallest cog has pointy shark teeth by design.
So how can I check (measure?) for wear on a particular cog or do I just have to wait until a new chain jumps off a cog under load?

Click to expand...

Without wishing to appear flippant my answer would be “yes” ride it until it jumps then replace.

billium said:

Old cassettes were easy to inspect - just look for 'sharks teeth' . Now I am looking at my Linkglide 11 speed cassette with 3000 miles on it and the tooth profile is all over the place!
The lower gears all have a symmetrical trough that is way wider than a chain roller so you cannot check for a tight fit. The smallest cog has pointy shark teeth by design.
So how can I check (measure?) for wear on a particular cog or do I just have to wait until a new chain jumps off a cog under load?

Click to expand...

Buy a new chain, if it still changes gear quickly and precisely and with no audible noises, clunkiness, intermittent rubbing etc then its fine. Shimano CN500 LG chains aren't expensive (around £18), so now you'll have two chains (presuming your original chain still has life in it), life becomes so much easier with two chains. No more last minute cleaning before you venture out (clean the one off the bike at your leisure), just slap the clean one on when needed, lube, job done. And buy some multi use speed/quick links, the standard Shimano ones are only good for around 3-4 chain swaps.