Replacement of Parts

[mountain_lion]

 

The info already posted will tell you how to measure your chain yourself to determine wear.

 

However proof of the pudding is in the eating...

You can just replace the chain and go for a ride.

If the chain skips on the cassette in some (or all) gears then the chain has worn the cassette to the point where it can no longer accept a new chain (this eventually happens to all cassettes).

You now have 2 options:

1. Replace chain and cassette

2. Keep the old chain and old cassette and ride it until you experience problems with it. Keep in mind that doing this will also accelerate wear on the front chain rings.

 

Very sound advice as always Mr Lion.

Also look for chainsuck with new chain/old chainrings: http://www.fagan.co.za/Bikes/Csuck/

 

Thanks Ninja

 

That link makes some interesting reading and seems to agree with me, giving more reasons (tooth loading) why a worn chain accelerates chain ring wear.

 

I am still interested to hear Johan's reasoning behind his view; I am no expert and might be convinced otherwise, given a sound explanation.

 

 

[Johan Bornman]

The info already posted will tell you how to measure your chain yourself to determine wear.

However proof of the pudding is in the eating...
You can just replace the chain and go for a ride.
If the chain skips on the cassette in some (or all) gears then the chain has worn the cassette to the point where it can no longer accept a new chain (this eventually happens to all cassettes).
You now have 2 options:
1. Replace chain and cassette
2. Keep the old chain and old cassette and ride it until you experience problems with it. Keep in mind that doing this will also accelerate wear on the front chain rings.

Very sound advice as always Mr Lion.
Also look for chainsuck with new chain/old chainrings: http://www.fagan.co.za/Bikes/Csuck/

Thanks Ninja

That link makes some interesting reading and seems to agree with me' date=' giving more reasons (tooth loading) why a worn chain accelerates chain ring wear.

I am still interested to hear Johan's reasoning behind his view; I am no expert and might be convinced otherwise, given a sound explanation.

[/quote']

 

Lion, I should have emphasised Accellerate not NOT. The point being that a worn chain will not wear the chainring more, it will just wear it in a different place, i.e. like you mentioned, at a larger radius (higher up on the tooth). The rate of wear will be the same as that for a new chain on a new chainring.  A new chain on that old sprocket will simply settle in its intended position at the root of the teeth on the old chainring.

 

An old chain will not mesh with a new chainring, and wil skip. This is the opposite of what happens at the back, where a new chain will not mesh with a worn sprocket.

 

I therefore see no reason why you should fear increased or accellerated wear on the front just 'cause your chain is worn.

 

Incidentally, I have read Jonathan Levy's piece many times over the years and I don't think he addresses this issue at all. The article is focussed on chainsuck, which is peripheral to this discussion.

 

Am I missing something in his article?

[mountain_lion]

 

 

Incidentally' date=' I have read Jonathan Levy's piece many times over the years and I don't think he addresses this issue at all. The article is focussed on chainsuck, which is peripheral to this discussion.

 

Am I missing something in his article?

[/quote']

 

Quoting Jonathan Levy from above link:

 

"Worn Teeth and Worn Chain : When chain wear / "stretch" makes its pitch greater than the tooth's effective

pitch, the geometric consequence is to transfer chain-roller/tooth

contact to only one or two top teeth (also increases tooth

wear/indentation). Slack in worn chain joints accumulates along the

wrap of the chain, allowing it to elongate and to give rollers more

play to float clear of the bottom teeth."

 

But OK, seems we are nit picking here.

 

Point I wanted to make was that you don't need to replace the chain and cassette immediately when the cassette is worn to the point where it will not accept a new chain.

 

 

[Johan Bornman]

Incidentally' date=' I have read Jonathan Levy's piece many times over the years and I don't think he addresses this issue at all. The article is focussed on chainsuck, which is peripheral to this discussion.

 

Am I missing something in his article?

[/quote']

Quoting Jonathan Levy from above link:

"Worn Teeth and Worn Chain : When chain wear / "stretch" makes its pitch greater than the tooth's effective pitch, the geometric consequence is to transfer chain-roller/tooth contact to only one or two top teeth (also increases tooth wear/indentation). Slack in worn chain joints accumulates along the wrap of the chain, allowing it to elongate and to give rollers more play to float clear of the bottom teeth."

But OK, seems we are nit picking here.

Point I wanted to make was that you don't need to replace the chain and cassette immediately when the cassette is worn to the point where it will not accept a new chain.

 

Nitpicking is good, this topic is something that confuses people. I continually have to refresh my thinking here too.

 

Jonathan's explanation above only holds true for a driven sprocket. In a driving sprocket the chain is forced in and will settle at the appropriate pitch diameter for its state of wear and.... if I visualise this correctly, engage all links/rollers equally and thus apply equal force to them all. If you put an old chain on a new chainring (driving sprocket), then only the first link on the sprocket wil be loaded and the one just before that, almost completely unloaded. In that scenario the chain will ride up and skip. However, just about no-one will do that, they'll put a new chain on when they change chainrings and therefore it is not something that is reported in chain discussions.

 

I think Jono can improve the clarity of his article by clearly distinguishing between driving and driven sprockets. Perhaps a matrix will help. That diagram just complicates a simple set of rules for chainsuck.