Cassette and chain

[jowwy]

I'm going to be changing my rear cassette from a 12/25 to a 13/26 will i need a new chain - current chain has about 600 miles usage??

its a 2300 sti set- up and putting on a sram cassette cause its lighter and i want the extra higher gear even though its only one tooth more, but its going on a brand new set of R500's

 

[HLaB]

It depends how your existing chain is set up (mine must have been right on the limit). I changed my cassette from a Shimano 11-25 to a SRAM 11-26 it was a link too short and it snagged and ripped the jockey wheel cage (the hanger designed to fail first was fine )

 

[jowwy]

i have bought a new chain - so may as well put that on there too - was hoping just to get away with it i suppose

 

[RecordAceFromNew]

Use a calculator. It lets you figure out whether you need to get your fingers dirty without getting your fingers dirty...

 

[andrew_s]

I'm going to be changing my rear cassette from a 12/25 to a 13/26 will i need a new chain - current chain has about 600 miles usage??
i want the extra higher gear

but this change will give you lower gears

You shouldn't need a new chain. It's unlikely to be too worn after only 600 miles, and the minimum chain length has gone up by only 1/4 inch, and the chance that the existing chain was that close to the limit is fairly low.

 

[jowwy]

sorry meant the lower gear for the hills