Campagnolo medium cage mech?

Adrian Waine

I'm currently running 10 speed Chorus with a compact at the front (50 / 34) and a 13 / 26 cassette.
I'd like to fit a 13 / 28 cassette. Can I do this on my existing short cage rear mech?
I read somewhere that the maximum difference was 29 teeth for a short cage, but I can't find that now.
Has anyone done this setup successfully?

Monty Dog

Short cage is fine up to 29 teeth sprocket

Adrian Waine

Thanks for reply. So if I fit a 13 / 28 cassette, that would make 31 teeth - had to recheck the maths there.
Do you know if that would be OK? I foresee a 'might be, might not be' situation developing here!

g00se

10 speed chorus is the old shape parallelogram and the short cage mech will have a max sprocket size of 26 and a wrap capacity of 30. See https://www.google.co.uk/url?sa=t&rct=j ... EH3Msnjwmg

Forgetting the max sprocket size, the 30 mean that with a 50/34 taking up 16 of that capacity (50 minus 34), you have 14 left for the rear. So with your 13/26, you're 1 away from the limit (26 minus 13).

Now, I think the 26 limit on the sprocket size is just an extra limitation imposed by their max chain wrap capacity - like your example, you're basically at the official limit with the 26 - so they say you can't go further than the 26 in conjunction with the compact front. Also, if you compare the short with the medium and long cages (max sprocket = 29), the geometries and top jockey positions are the same - so the sort cage should take a 29 easily - without the top jockey fouling the sprocket.

With a 13/28, you'll be 1 over the limit - but most seem to assume that you can exceed Campag's specs by a couple of points easily. In fact, with the right chain stay length (effecting the ideal chain length), you could even get a couple more.

As an example, I have a 2010 Centaur short cage mech (identical geometry to yours). I run 50/34 at the front and a Miche 12/29 at the back. I'm over by 3 and I reckon I could get another tooth's difference in there too.

rolf_f

g00se wrote:

As an example, I have a 2010 Centaur short cage mech (identical geometry to yours). I run 50/34 at the front and a Miche 12/29 at the back. I'm over by 3 and I reckon I could get another tooth's difference in there too.

I run a similar rear mech and have a 50-34 and 13-29 which I sometimes use. I certainly thought I had capacity for at least 1 more tooth and probably more.

13-28 ought to be easy!

Adrian Waine

Thanks for that guys.
Going home to break open the piggy bank.