When do we change these?

[gavroche]

My LBS recommends a new chain every 2000 miles. How does the chain wear out by the way? Does it strectch? I can't really see that as it is made of metal links?
My 20 year old MTB still has original chain and tyres. ( Maybe it is because I never used it for a 10 year period?)

 

[black'n'yellow]

How does the chain wear out by the way? Does it strectch? I can't really see that as it is made of metal links?

the side plates don't actually 'stretch' as such, but the pins, rollers and bushes will wear over time - which effectively extends the length of the chain.

 

[User6179]

My LBS recommends a new chain every 2000 miles. How does the chain wear out by the way? Does it strectch? I can't really see that as it is made of metal links?
My 20 year old MTB still has original chain and tyres. ( Maybe it is because I never used it for a 10 year period?)

When I changed my chain at 5000 miles it was 40mm longer than it should of been , nearly at 3000 miles for new chain and still on original cassette(ultegra)

 

[Globalti]

If you're in the habit of "bending" your chain by riding with it on extreme - extreme it will wear out much faster.