not likely. changing the front crankset (chainrings and what not), as long as it is compatable to the bike and bb, it doesn't really matter if you have 5,6,7,8,9, or 10 rear cogs/gears. just make sure the new cranksett fits the bike proporly and your front deraillur travel can take the extra range if you do add more gears on the rear, as more rear gears will increase the angle the chain must travel to hit all rear gears.