bought new carrera vengance bike for my son, it was assembled by halfords in KIrktall. When we got got it home noticed thefront wheel & handlebars weren't allignned & steering wasn't tightened. He rode it to his friends the day after using road & track for the approx half mile journey, when he came down the drive the back wheel came loose & the derailer trapped in wheel spokes bending it round & damaging the frame. I rang both Kirksatall & my local Keighley branches several times to no avail. I took bike back to Keighley, where the staff were apologetic & helpful & ordrered a new bike.It was mentioned that they've had problems with the rear wheel of carreras, I did question how it had been built & safety checked by 2 of Halfords technicians? A bike with loose steering plus wheels that fly off is an accident waiting to happen, my son was lucky not to be injured, and it's complete incompetence. Keighley agreed & promised my new bike will be built by senior technician & checked by manager. I felt better with regard to this stores competence until on leaving we met a lady who had just picked up her new carrera bike to discover the back wheel was loose! My confidence in my new bike being safe is low