Cannondale SystemSix Team Si

Hopefully not jumping the gun to say this; but I think we've cracked it. The new SRAM Red 22 chainrings (thanks for the speedy postage @noBlakes ) helped a bit (Thanks again @Howard for lending me the hologram spider tool) but not much, they do look nicer though and shift much better than the praxis:

I'd been told that Q rings XL use a shim to push the derailleur back into a position where it can shift as the 'peak' of the ring passes and I was wondering if this would help with me as it would mean that it would move the chain up the derailleur to a wider area hopefully stopping the rub. I was looking into this shim and I discovered that Rotor charge £25 for this small 12mm piece of plastic, so in looking for a cheaper alternative I found that SRAM actually make an angled shim for bikes using compacts with a certain angle of seat tube (thats also only a tenner):

So I asked @CleverMike to test out the principal with a washer, before I spend even more money on this bike. which he did with a small piece of metal clamped in the band on:

Apparently the results are instant; the mech was in a much better position right away and generally shifting as its meant to in the first place:

So we've tracked down the part number for the SRAM shim and it should be here tomorrow so I can go for a ride on sunday if I'm not to knackered from cross on saturday!

So pleased that it's finally working!