12-29 chorus cassette

[Nozzer]

I have athena compact groupset with a 11-25 cassette, would like to change to a 12-29 chorus, will i need to add links or can i just swap with hopefully no issues?

 

[PpPete]

Check the specification of your rear mech too. If it's short cage it may not stretch to a 29T. If it's a medium cage you shouldn't have any issues.

 

[Nozzer]

Ive just got bike second hand so not sure, is there anything i can check to see if a small or med cage?

 

[fossyant]

Athena (11 speed) should take a 29 - thought the newer stuff could.

 

[Nozzer]

Thank you, its 2010 athena, so i shouldnt need to add links?
As guessed, im a bit of a spanner!!

 

[accountantpete]

Ive just got bike second hand so not sure, is there anything i can check to see if a small or med cage?

The short cage (I think) for Campy rear mechs measures somewhere around 55mm. This is the gap between the jockey wheels centre to centre.

 

[PpPete]

Take a pic of it and post on here.

 

[Nozzer]

 

[RecordAceFromNew]

As others have said it is important to check. The issue about the rear mech is that the cage length governs the wrap range, assuming you have a 50/34 chainset, a short cage (as AccountantPete said 55mm between the centres of the jocket wheels) will most probably be unable to handle a 12-29 at the back, while a medium cage (72.5mm) will be fine. This provides a good write-up.

Regarding whether you need a new chain, the most reliable way (using a chain that is too short can wreck your drivetrain components) is to use a chain length calculator, which will tell you what length you need for different large chainset/cassette cog sizes, all you need to do is to supply the distance between the centre of the chainset and the centre of the rear wheel axle.

 

[Nozzer]

very interesting, are those CW ratings the same for 11 speed?

 

[RecordAceFromNew]

very interesting, are those CW ratings the same for 11 speed?

The number of sprockets (speeds) front or back has no bearing on chain wrap for all intent and purpose, only the sizes of the sprockets do.

 

[PpPete]

Probably - if the cage lengths are the same.

 

[youngoldbloke]

(as Fossyant said) I thought the new Campag mechs - eg Athena - only come with one cage length that will accomodate 29T? May be wrong but suggest you consult the official Campag specs. Agree re use chain length calculator. I increased from 25 to 27 (older short cage Veloce mech) wiithout having to change the number of links.

 

[RecordAceFromNew]

Actually I stand corrected. According to their latest technical manual (page 47), despite having a 55mm cage length the 11S have wrap capacity of 33T, if that is what you have.

 

[Nozzer]

Yes a compact and 12-29= wrap of 33 I think, so looks like it will work, just need a link or 2 then? Thanks so much for your help