My Decathlon Rockrider 5.2 is 1 year old and has probably done about 1000 miles (mostly on road). I have just stripped the hubs for a bearing regrease. Both sets of cones showed wear, the front needs replacing. It'd cost me £3 in petrol to get to the store to drop the wheel off and another £3 to get it back, so I ordered the parts myself. Axle, cones and bearings £6.60 delivered. The bearings appear to have been set too tight so that when the QR skewers are closed it has caused excessive wear. The Hubs are Joytech - cheap, but set correctly shouldn't have worn. I will pop in and see the customer service desk next time I'm in there. Decathlon have 2 years warranty on parts. It's worth checking new bikes for correct cone adjustment I think. They seem poorly set up from the factory.