Time to open your wallet then. I wouldn't be starting from where you are, but if you're committed to an OTP bike with 6800, ask your dealer what they can do as deal to swap out the RD, cassette and chain to RD-R8000-GS + CS-HG800 11-34 and a suitable longer chain
thanks - a day of research suggests 30T would be ok on a short cage + extra links (or new chain) so i think i'll try that and see , if all else fails then i can sell on my brand new chain/cassette and short cage rear and buy a new mech....
Time to open your wallet then. I wouldn't be starting from where you are, but if you're committed to an OTP bike with 6800, ask your dealer what they can do as deal to swap out the RD, cassette and chain to RD-R8000-GS + CS-HG800 11-34 and a suitable longer chain