hi all, bought a 2010 allez sport 27 speed with upgraded tiagra gears, tiagra sti shifters and tiagra chainring. seem to be continually messing with the gear set up so am thinking of changing to single speed as i am told this way i wont have to change the rear wheel. any advice appreciated and does anyone know how much i am likely to get for tiagra bits and pieces and how much is it likely to cost for decent quality ss conversion? cheers. btw im a complete mechanical numpty so please reply in idiot-proof laymens terms!!