Cassettes compatibility? help, please

[Jon C C on a Bianchi]

Jon

probably a daft question but did you have to lengthen the chain for the 12-27?

[Andrew G]

A new chain will be long enough to cover a compact and a 12-27 with some to spare (remove), if you shortened your original and have the spare links then you can add them back in to give you the desired length. I'm personally not a huge fan of this with modern 9/10 speed chains as they are so narrow they tend not to stand up to splitting and re-joining as well. I'm sure some find it okay but I've always found it weakens them. I'd get a new chain and keep Sam's one as a spare for yourself for when you wear that out.

[Jon C C on a Bianchi]

Andrew

hi. I'm really asking if i buy a new bike for sam with a 12-25 cassette and 50/34T compact, replace the cassette with a 12-27 (like Jon H), would I have to also change the chain for a longer one as the 27 cog/sprocket is physically bigger. Does this make sense?

Also really pushing it - the SRAM 11-28 10 speed would give the same ratio (give or take 0.1) as Sam's triple - would this mean having to change the rear mech or whatever or like Jon H and his 12-27 would it be a straight no hassle swap? do you know anyone who's tried it?

Thanks

Jon

PS I take the point about hanging on until the sales - tempting

[quote]I'm really asking if i buy a new bike for sam with a 12-25 cassette and 50/34T compact, replace the cassette with a 12-27 (like Jon H), would I have to also change the chain for a longer one as the 27 cog/sprocket is physically bigger. Does this make sense?

[Jon C C on a Bianchi]

thanks Andrew

I think I'm getting there

yes, sorry for the confusion i'm now looking at a 10 speed - the boardman i was looking at is a 9 speed. Just exploring all possible options!


BTW I had a look at the Ribble site - bikes look a good deal but so many variables...which is good...but I wouldn't know where to begin...which is bad!!

I'm now in a much better position to make a decision and realise what is possible and what is not.

I now need to lie down in a darkened room.

Cheers

Jon