On the 5th and 6th gears (starting from the smallest), it slips every time when applying force.
So could it be that my cassette is worn out?

Yes that's the tell tale sign your cassette is worn. Especially the gears you likely use the most.

How many miles/km do you have on the cassette?

 

Yes. Additionally, skipping after a chain is replaced is very common as the new chain will not match the profile of the worn cogs.

 

Many of the teeth on your cassette look noticeably and irregularly worn, especially on the 5th and 6th cogs that you mention. If you can see this upon a quick visual assessment, it's likely your cassette should have been replaced a while ago.

The easiest way to prolong the overall life of your drive train is to make sure your chain is kept clean and lubricated, and replace it when it reaches ~.5% wear. This will be more economical in the long run as it saves wear and tear on more expensive components.

 

lubricated

Here we go...

 

Best to replace the chain rings when doing the cassette. If the chain went beyond specs, it would wear both. If you don't change the chain rings, you will be putting added stress on the new chain and it will lead to a shorter life and back to square one sooner.

 

Wrong. An elongated chain will wear your cassette and chain rings prematurely. Worn cogs or rings won't wear a chain prematurely unless they are already skipping.

 

It also depends on how hard one pushes on the pedals, IMO.

 

Quit before you dig even deeper.

 

Pretty sure if your a 50w spinner, your chain is going to wear less than 500W sprinter. Dah!

 

Correct. But you are completely wrong about changing chain rings when you change the cassette. I have NEVER had a chain ring wear anywhere near as fast as a cassette. I typically get around 15K miles per cassette, and 60K miles per chain ring.

 

@MNRICK and @jta ,

You are at two ends of the extreme. 25,000 miles is an outlier, and you must be doing something right if you can get your chain to last that long without trashing both your cassette and crankset.

The 0.5% wear guideline is just a number. How do you measure 0.5%? Even the Park Chain Checker registers around 0.25-0.5% when the chain is brand new. They say to replace when it reads 1%. But heck if I were to have believed that tool, I would have replaced my chain long before it needed it. The humble ruler told me it was still OK until 8,000 miles. So I replaced the chain then. And guess what? It still shifts perfectly in all gears!

 

Thanks – I’m pretty practical/proactive about maintenance and just replace chains when they reach between .5 and .75% on geared bikes and 1% on single-speed chains. I’ve never bothered to note mileage on my chains, cassettes and chainrings but will start. Curious to see other data points.

Speaking of CX and the raging chainring debate, I recall him stating in a post that he’s never had to replace a worn chainring on a road bike in 40 years of riding and weirdly, I found it. See post 3:
https://www.roadbikereview.com/threads/chain-ring-life.367627/ Ahem, duriel?

Hilariously, he knocked the OP for posting in the wrong subforum, but at least gave him credit for missing it by only one. Must've been in a good mood.

 

I haven't ever replaced a chainring either, I don't even think I've replaced a cassette due to wear.
In CX case, he didn't cause he replace the whole bike. Just like the racing team bikes, they are replaced every year. So, ... their situation isn't the same. For me and CX, i just never road any one bike long enough to wear it out, or I was changing cassettes for hills, or getting a new bike. I have a main road bike but got a new one every 2-4 years, I have 24 YO bikes, but they are special day bikes, not my regular ride.
I don't have any scientific data on the wear of a chainring, only engineering analysis skills. I'm open to any actual data if anyone can find any, other than ...crazy joe thinks your crazy!

 

I haven't ever replaced a chainring either, I don't even think I've replaced a cassette due to wear.
In CX case, he didn't cause he replace the whole bike. Just like the racing team bikes, they are replaced every year. So, ... their situation isn't the same. For me and CX, i just never road any one bike long enough to wear it out, or I was changing cassettes for hills, or getting a new bike. I have a main road bike but got a new one every 2-4 years, I have 24 YO bikes, but they are special day bikes, not my regular ride.
I don't have any scientific data on the wear of a chainring, only engineering analysis skills. I'm open to any actual data if anyone can find any, other than ...crazy joe thinks your crazy!

The gist of cx’s post was that chainrings don’t wear out nearly as quickly as chains and cassettes. Same for the other posts and virtually all other threads and tutorials I have seen on the topic. So, you don’t have any scientific data to prove your point but everybody else is a “crazy joe”?

There must be a secret conspiracy to prevent all these people from telling their truths about chainring wear.

 

Well, crazy joe hasn't popped in here yet, but he will shortly I'm sure of it.
As I posted, it was thoughts on actually what happens to the chainring. Now, more thoughts, say you typically run 16mph in your 23/50 gear; based on that your chainring should wear out in about 2 cassettes based on the ratio. But, the cassette has more gears, but again, one only really wears out 2 or 3 of them. But realisticly, for U & me, not being a pro level output, they really would probably never wear out, we don't really do the power.