I have a triple/9sd that came with 9spd sora shifters. Found some 10spd Ultegra shifters dirt cheap, and planned on adding a flight deck computer.
I used the alternative cable routing, setting it up so that when I was on the smallest cog, the shifter would be in "9th", and that when clicked to "10th", there would be no change. This worked perfectly until I added the flight deck.
I programmed the flight deck for 9 speeds, but anytime I click into what would be "10th", the flight deck computer would begin to act funny and read the wrong gear. I tried to setup the gear changes so that the largest gear would be "2nd" on the shifter, but that created too many other shifting issues.
Is the simplest solution to simply get a 10spd cassette? and chain? Can I still use the same crankset, or would the narrower chain not work?