I have Giant SCR 2, love the bike but would like to upgrade the wheels from the standard Alex items, my budget would be up to £120. I have seen theVuelta Zerolite complete with tyres and tubes for £90.00. Would this be a reasonable upgrade or should I look at a pair of level entry Marvic or Shimano wheels. Also is it as simple as just changing the wheel or will I need to adjust the gears to account for the new wheel. Any advice gratefully received!