My cx bike curretly has a 36/46 chaingring set up with 11/28 outback. I use the bike for mix of on road and off road forest road / bridleway / sustrans type stuff. I was think of putting a 34t inner chainring on to help out with some of the long grinding forest road climbs around here (s/mid wales). Will this muck up the chain length?? Will the chiain be too slack when I am in the higher end of the casette i.e. 28 etc and would I need something like a corresponding 44 outer chainring. Ta.