I think you mean chainring on the front but if you do do the one cog up front you only need the one shifter for the rear derailler. If your doing jumping or something it might be good to have one of those chain tensioner whatever you call them things to prevent the chain from jumping off the teeth. If you have a triple crankset you could just leave it on whichever ring you prefer. Or you could have one chainring with a bashguard and the tensioner thing.