2014 Specialized Allez Sport - Front Mech Size

GumGum2804 Posts: 3
edited November 2014 in Workshop
I am upgrading from Sora to a 105 groupset which comes with a braze on front mech so I need to buy a band on separately. Could anyone please tell me if I need a 31.8mm or 34.9mm.

I know I can just get a braze/band adaptor but would rather get a band on mech.

Many thanks in advance.