In a case like this with limited (initial) info given, it could make a massive difference, The OP has now stated they have and are going from a to a triple, so it's a pretty simple swap (on the basis that the BB types are the same). Initially no specifics were provided, so if they were going to a single, they would need to look at removing the FD, front shifter, and getting a larger range cassette, maybe even new RD & rear a wheel if they needed to swap from a Shimano/Sram cassette to and XD cassette, so a lot to think about till full info is given.