Cassette Size ?

[weaty]

Hi
I have a 48-34 chainset with a 105 long cage rear mech, what is the biggest cassette I will get away with ?
I used an mtb 12-34t cassette last year thinking my 105 was the same as an mtb rear mech, but I have
now realised this is not the case It slipped badly.
Looking at some threads on other forums it looks like 12 -28 is the biggest I will get away with !

Thanks for any help

[rammy]

Yes, from what i've learned so far, a 28T cassette is the biggest you'll safely run with a 105 rear mech. I've got a 30T on right now but the top jockey wheel looks alarming close to the 30T cog, too close for comfort.

[weaty]

Thats what I thought, looks like I will have to try an mtb rear mech, does anyone know if a shimano mtb rear mech
will work with 105 shifters ? I think I have read somewhere that it will not shift correctly.
Thanks
P

[Lowly Swale]

Old 105 flight deck 9spd shifters seem to work for me with XT mech and cassette. Just a bit of interference noise on one end or the other depending on how its adjusted. I tend to have the noise on 48x 14, 12 and 11 cos they don't get much use. I'm on ultegra triple front 26-38-48 with 11-32 cass. The granny is usually pretty useful going up Pen y ghent

[weaty]

Thanks for that, I think that is the answer I am looking for, mine are the old 9 speeds as you say
so I will try and search out or steal what I need from my mtb,s

Cheers
P