Decent mileage for a chainset?

[merlin321]

Hi, I have an SCR2 with a triple chainring. The bike has done nearly 8,000 miles in about 12 months. I had to take it to my lbs today to get a new bottom bracket fitted , I`m severely mechanically challenged, and they said that the chainring was due for replacement.
Is this about right given the mileage?
It had a new chain about 3,000 miles ago along with a new rear cassette. The lbs said it would be a good idea to get all three done at the same time.

Cheers.

 

[RedBike]

It all depends on how often yoiu change the chain.

As the chain wears it stretches. A stretched chain then starts to wear out the cassette and chainrings at a MUCH higher rate than a new chain.

If you were to keep changing the chain before its stretched too much and keep everything well lubed and clean then your chainrings (and cassette) would wear at a very slow rate and last far longer.

If you were to use a new chain on worn sprockets there's the likely hood of the chain slipping or chain suck and the chain would wear very quickly to match the sprockets; so within weeks your new chain would be worn out too. This is why it's often sensible to replace a cassette /chainrings at the same time as the chain if they are worn.

So in answer to your question. Yes, it's quite possible the chainrings do need replacing at just 8000 miles. Yes, a chain used on worn sprockets could well of worn out in just 3000 miles.

However, a bottom bracket shouldn't really of failed within a year / 8000miles. I would ask for that to be changed under warrenty.




With chains you basically have two options.....

You can keep replacing your chain BEFORE it wears out. A chain is worn when 12 full links measure more than 1/16th over 12". In theory you will never need to buy a new chainring/cassette again but new chains are going to cost you a fortune.

Or

You can keep the same chain, cassette and chainrings and just run it all into the ground until something breaks and then replace the entire lot all at once.

 

[merlin321]

RedBike, thanks for that. If it seems a reasonable mileage, I`ll take the "replace the lot" option and hopefully save any roadside disasters with anything failing.

I understand what chain slip is, but chain suck?
Can I ask my lbs to do that or is it prescription only??

 

[RedBike]

Its very hard to say if it's a reasonable mileage or not. I wouldn't be happy if my chainrings (or cassette) failed on my race bike at just 8000miles.
Yet on the other side of the coin my commuter (which basically isn't looked after) probably doesn't manage anything like that.

Chain suck is more or less the opposite of slipping. The chain doesn't seperate from the bottom of the chainring and continues to wrap around it as you pedal.

I don't understand what your asking your LBS to do. To see if the chains worn just get a ruler and measure 12 links. A new chain will measure 12" exactly.

If you buy sram or KMC chains with a link then i'm sure you'll manage to fit them yourself. You'll need a chain splitter to shorten the new chain / remove the old one; but these are normally only about £5.

 

[Deleted member 1258]

However, a bottom bracket shouldn't really of failed within a year / 8000miles. I would ask for that to be changed under warrenty.

On the last three new bikes i have brought the original bottom brackets have all failed inside twelve months. On two of them the replacements have lasted several years. Unfortunately the third bike, a pearson touche fixed has an appetite for bottom brackets and gets through them in just over twelve months.

 

[itisaboutthebike]

In a lot of cases sprocket/chain and BB wear has a lot to do with;

a) how clean you keep the chain/sprockets

how often and HOW you change gear

c) to a lesser extent your pedalling style (particularly for BB's) which can cause excessive wear

I'd say 3,000 miles for a chain and 8,000 miles for a BB is pretty much in the right ball park

 

[andrew_s]

Bottom bracket life depends quite a lot on what type they are. It used to be normal to get 40,000 miles out of an old square taper UN72 or whatever, but Isis/Octalink would often fail in as little as 3000 miles.

 

[Bigtwin]

Get two chains with your next new driveline.

Change them around every 500 miles or so if possible.

You'll get a hell of a lot longer wear out of everything.

 

[joebe]

Assuming all receive similar usage, the smaller the chain ring, the faster it'll wear out, simply because there is less of the chain in contact with it, i.e. each tooth bears a greater load. My 53 chain ring is still going strong after 13000+ miles. I did replace the bb at about 10K though.

 

[Bigtwin]

Assuming all receive similar usage, the smaller the chain ring, the faster it'll wear out, simply because there is less of the chain in contact with it, i.e. each tooth bears a greater load. My 53 chain ring is still going strong after 13000+ miles. I did replace the bb at about 10K though.

That and the fact that the smaller the ring, the more time the chain spends in contact with it - there is literally less to go round.