Can I just let the chain/cassette/big chainring all wear out together now and replace later?

[Tapper3279]

Hi all,

I have my first sportive in 5 September (Tour o the Borders) and so I took my bike in to Decathlon for its free safety check seeing as I have had my bike for about a year now.

Unfortunately they told me that my chain/cassette/big chainring was all worn out. I had actually only changed the cassette and chain back in October 2020 when I had changed over to these -

• Shimano CASSETTE HG400
• Bicycle Chain 8 /9/ 10 /11 Speed Gear

It does seem a bit premature with the wear but I will chalk that up to me switching over to using Squirt Lube a few months ago and not degreasing it properly! and also maybe it was a cheap chain from ebay.

None of my gears are slipping just now so the bike still works although changing gears isn't as smooth as it used to be!

But can anyone confirm to me that I can just keep riding the bike as is just now until my gears start slipping and that this won't cause any damage to anything else on the bike? apart from the three components which are already worn out?

I am buying the following components just now and just about a week before the sportive I will change them over -

• Shimano Alivio CS-HG400
• KMC X9 Chain
• Chainring 50T Sora FC-3550

Any advice would be appreciated thanks!

 

[OldShep]

Of course you can. Might be a bit noisy and rubbish changes.
An example of false economy buying an unbranded chain perhaps.
What about the 34 ring? You’ll need it up Talla

 

[T4tomo]

I am buying the following components just now and just about a week before the sportive I will change them over -

Give yourself more than a week . You need to test it out on a decent ride and make sure all is well and allow for any tinkering / adjustment with indexing if necessary..

 

[Milkfloat]

Seems like an awfully short amount of time to trash the drivetrain. Do you ride a considerable number of miles per year and is it predominately off road?

 

[Mo1959]

Seems like an awfully short amount of time to trash the drivetrain. Do you ride a considerable number of miles per year and is it predominately off road?

That's what I was thinking! Some of my bikes are several years old and still on the same chainrings. I do the chain and cassettes maybe every 18 months or so.

 

[T4tomo]

Seems like an awfully short amount of time to trash the drivetrain. Do you ride a considerable number of miles per year and is it predominately off road?

I was thinking that too - maybe Decathlon mechanics are as good as the majority of halfords ones....

 

[raggydoll]

How many miles have you done on the bike in that year?

I find it hard to believe that you have worn out your big chainring in a year.
Of course, it could just be a cheap chainring with soft metal..but I still doubt it needs replaced so soon.

Given that you have already changed the chain and cassette and it wasn't skipping.

In general:
Your chain will wear down first.
If you keep on top of measuring your chain (easies with a chain checker) you can replace just the chain.
Doing it this way can mean you can replace just the chain. NOo an exact science but if you change the chain just as it gets to 0.75% you can potentially get 3 chains to 1 cassette.
Leave the chain too long and it will wear out the cassette....so you replace both.
Last to be worn out is usually the chainrings....but keeping on top of the chain an cassette, chainrings should last waaaaay longer than a year.

I would get a second opinion if I were you.
Might just be a case of offering a free safety check and telling people it needs stuff done that it doesn't to make a bit of money.

I've had it before with arnold shark...your windscreen wipers need replaced. We can do that today for £xx.
No thanks.
Didn't replace them...a year later and a winter later.
Go back for another service and what do you know...the same windscreen wipers don't need replaced...a year later!

Even if you post a photo of the chainring here.
Worn out chainrings go sharktoothed and pointy and are easy to see if they are worn.

 

[Broadside]

You can run a drivetrain in to the ground, I clocked up over 7,000 miles on one bike before changing anything and the had to do the cassette, chain and big ring at the same time. The jockey wheels were also very worn but I didn’t bother changing them. The bigger risk you run is that after a lot of miles the chain will be at higher risk of snapping and it was this that made me change it all.

I have takenthe opposite approach with my current bike, the cassette alone is £80 and the chainring it not replaceable so it would mean a new crankset, so now I just wmswap the chain every 2000 miles or before it gets to 0.75% worn, I’m on my third chain and the original cassette.

I think for most bikes the costs of running it in to the ground and getting a big bill versus timely changing with more but smaller bills are broadly similar overall but now prefer more regular maintenance option so I have less chance of issues out on the road.

 

[weareHKR]

Yeah get a couple of good pictures of Chainring & cassette

 

[mickle]

It's extremely unlikely that your big ring is worn out. Perhaps your mechanic has made the classic mistake of looking at the different tooth profiles on your ring (designed to aid in under-load shifting) and mistaken them for wear. So either he's an idiot or a liar. It's extremely unlikely that your big ring is worn out.

 

[Dogtrousers]

Seems like an awfully short amount of time to trash the drivetrain. Do you ride a considerable number of miles per year and is it predominately off road?

It does, but it is possible to completely bugger a modern 10sp drivetrain remarkably quickly by riding in all weathers and not being particularly fastidious about cleaning. DAMHIKT.

 

[si_c]

As above, you should expect well over 15k miles from a Shimano road chainring in my experience, unless you're riding on a wet beach constantly.

Get a chain checker and measure your chain, if the chain is over .75% lenghtened then replace the chain, you'll know if the cassette is worn as it will slip immediately after changing the chain, so grab a spare cassette when you get a replacement chain, it's worth having a spare on hand anyway given the current spares market.

 

[T4tomo]

That's what I was thinking! Some of my bikes are several years old and still on the same chainrings. I do the chain and cassettes maybe every 18 months or so.

whisper it quietly, but I have bikes that are 30-40 years old that are on their original cassettes / freewheels . Steel freewheels do weigh a lot though, even in 5 speed, so I sort of see why the industry switched to alloy. I also have 6-10 year old modern bikes happily running on the original alloy chainring(s).

 

[raggydoll]

I've never changed a chainring yet.
I find if you change chain and cassette when they need changed then chainrings last and last.

 

[battered]

I've never changed a chainring yet.
I find if you change chain and cassette when they need changed then chainrings last and last.

Similar here. I changed one on a MTB but it was still working and the middle ring is still in use on my single speed bike. If you bother to oil the thing chainrings thy last for ever. I'd buy a chain wear gauge, I got one for £3 or something daft, and verify what they say. I'd also look at the teeth, if they really are worn out you get a change in shape on the chainring and the cassette teeth start to get a bit "mushroomed" where the load side gets crushed by the chain and starts to mushroom out, rather like you get with an old chisel that has spent years being battered by various hammers.