I'm seriously considering buying a new 705 Torque model bike but they now come with a 7 speed freewheel and shifter. Is it straightforward to install an 8 speed freewheel and 8 speed shifter? I am mechanically competent. I believe an 8 speed freewheel is slightly wider than a 7 speed one so is an adjustment needed to the hub spacing? Maybe its as simple as discarding a spacer? Thanks.