How to know when a cassette needs to be replaced.... I got a sign.
 

I have a tad over 28,000 miles on my Red eTap drivetrain. I regularly check the chain for wear and replace and it reaches the .5 mark. But how do you know when the chainrings and cassette should be replaced? I regularly clean everything and over the winter I use a ultrasonic cleaner to get everything really clean.

Over last winter I got a great deal on new chainrings, chain and cassette and set them aside. This weekend I checked the chain and it was time to be replaced. Today I went for a ride and found the chain skipping occasionally when in the 5th cog (19 teeth), which is the one I ride in mostly. It happened in both the 50T and 34T, but not in any of the other cogs.

I went ahead and replace the cassette and it works perfectly, so I guess it was a sign from above.

I just find it odd that the skipping didn't happen with the worn chain.

https://i.imgur.com/ReJre7q.jpg

My old cassette after being cheaned.
https://i.imgur.com/m2S6Cvz.jpg

Nothing odd about that, it's totally normal. The cogs wear to fit the worn chain, seems okay but efficiency suffers. Slap a fresh chain on, worn cogs say nope.

Same if you put a fresh chainring on with a worn chain. If the driving part is new and the driven part is old, it's likely to skip. Not so much the other way round.

So i should replaced the chainrings also, since I have them.

I'm kind of like the person who's leased cars for years and decided to buy one never having one long enough to the brakes, tires and timing belt need to be replaced.

I've replaced tires, tubes, chains and brake pads. Two years ago i replaced the bottom bracket and jockey wheels when I had the carbon frame repaired. I guess I reached the time to replace the chainrings and cassette. I'm also planning on servicing the hubs and pedals over the winter.

If you had 28k miles on the old cassette, it was probably long overdue for replacement. The problem is that the wear occurs so gradually that it might be difficult to recognize when it is time.

28,000 miles!!!! wow

I would visually inspect it but wasn't sure I would recognize wear.

I did keep it spotless, cleaning it once every week and regularly checking the chain. I contribute replacing the chain once the .5 wear nark was reached to it's long life.

Yep, scrupulous chain replacement will prolong cassette life, that's for sure. But I have found that 11 speed Shimano cassettes don't last very long -- I get about 3500 miles before they get noisy. Just replaced one about two weeks ago for that reason, though it had about 4200 miles.

At $250-$300 doe Dura Ace,that can get expensive.

The Sram Red cassette is a single piece with only the 11T being separate. With Shimano, can you buy individual cogs?

Maybe hold off on the chainrings unless you are having problems. You should be able to go through a few cassettes before you need new rings. Of course 28,000 miles would normally be several cassettes.....:foo: You got your money's worth from that one!

Lol, not since the UniGlide days.

Don't be in a rush to change your chainrings; they generally last a lot longer than cassettes if you change your chains in time. Also, a worn chainring has to be pretty bad to skip under a new chain.

If you change your chains early, you should be able to manage two or three chains per cassette, and maybe up to ten chains for your most used chainring. Let your chains go, and you'll need a new cassette every time and only get a few chains per chainring at best.

Since you've got new rings handy, examine your old rings in comparison to the new.

A worn chainring with a new chain won’t skip, but it will cause “chain suck”, where the chain won’t disengage at the bottom of the ring. Chain suck usually happens when shifting. It can cause a mess, as it may pull off the rear derailleur, wrecking the derailleur hanger.

On my old Giant, I put the last freewheel and chain together in a bag for emergency use because they still worked great together, just not with new partners.

You can usually visualize with a new chain if the chainring is worn. Hang the bike from something so its eye level and spin the crank a couple turns, the goal is to move the chain on the chainring with minimal pull or tension from the pedal or rear wheel so you can see how the chain settles onto the chainring. If you can see a gap between the chain and the valleys of the chainring, the ring is worn and the chain isn't settling into the ring as it should. You'll also notice that you can take a finger and push the chain down into the ring as it is effectively floating along the ring. If there isn't a visible gap or when you push on the chain it barely moves, your ring is fine.

Thanks Russ.

The wear has to be pretty horrific for that, no? Don't think I've come across chain suck more than a couple of times.

:foo:

Is the chain on your "favorite" sprocket? It makes it hard to visualize the issues.

I have heard that SRAM hardens their SRAM Red cassettes. Expensive, but likely part of your longevity. As well as using a mid size sprocket, and likely spinning a lot.


What I tend to see on a worn cassette is stretching and mashing of the pulling side of the valleys between teeth. And, slightly more angled teeth.

I have had a new chain skip, but it subsided after a short while. That same cassette is used with one more new chain, the was changed sooner, with no issues at all.

Not in that picture, it was taken previously and posted to demonstrate how clean I keep it.

Jinxed myself.

It assploded about 25 miles from home. It wasn't bad riding, just had to be a bit careful.
https://i.imgur.com/UG00CYt.jpg

While rings don't wear out as easily SRAM ones in the 10 and 11 speed generation tend to be a bit softer than one would expect. Visual inspection can usually lead me to an indication that there's "some" wear there. If there is and I can pick up "gear mesh" or small harmonics while running it with a new chain then I usually swap the ring. Everything tightens up and it sounds great and it's then you realize how worn it really was. Usually a semi-inexpensive fix.

Pretty rare event, yes. But I've had chain suck break my derailleur hanger twice. Both times when shifting down to the small ring at the bottom of a climb, after installing a new chain.

You need a Rohloff HG-Check:
https://cimg0.ibsrv.net/gimg/bikefor...de8ceeb70a.png

They work great on old drivetrains. Specifically 8/9 speed and below. The tool itself is a bit too wide to work well on modern stuff (although I still use it as a point of reference). I have without a doubt had my Rohloff say a cassette was good only to have the drivetrain issues be eliminated by replacing the cassette.

This is similar to chain wear now. Elongation isn't the only measure of chain performance. the chainlines are so short now and angles so great that lateral stiffness is playing a larger role. We have run into chains that are worn enough laterally that they no longer perform well but measure well under what we would consider to be replacement level for elongation.

I usually rotate three chains with each cassette, rewaxing each chain when it rotates off every 300-400 miles. I aim for ~12,000 miles per cassette/chain set. I change chainrings only if they're noisy when I install a new cassette/chain set. I replace the big chainring every 2-3 cassettes, the small ring less frequently

Lube and maintenance have a huge impact on longevity of the drivetrain. I'm an engineer and pretty anal about maintenance. Last year I switched to Silca's new wax based lube. Normally, I get about 1500-2000 miles to a chain. I'm at 4500 miles on my current one and I'm not even to 0.3mm worn. That's impressive in my book. I'm guessing I'll be at around 6000-8000 miles before the wear says to change it. That's amazing to me what difference the lube makes. No other lube I've tried in 15 years has made that much of a difference.

I wasted a day on vacation when I changed a chain at home, drove to the mountains and set up to ride. The chain was skipping so I had to pack up and head home. Turns out it was a worn small chainring that wouldn't work with the new chain. Same thing happened to my son only it was his rear cassette with about 12,000 miles on it.

My general rule of thumb is cassette tossed every 3-4 chains. Same for small chainring, add one more for large chainring (this will vary by rider and terrain). Yeah, I may be not *totally* wearing them out but then again, I'm not going to blow a long drive and an epic ride either not to mention all the aggravation that goes with that. If you keep all the wear close to nominal, it just goes better and you have less problems. The marginal cost difference is easily worth it to me to avoid a lost day.

Bottom brackets are cheap and easy to change. I just change them every 8000 miles which works out to every other year for me. For the 10 minutes and $40 for a new one, I'd just change them out every other year anyhow and stay ahead of the curve.