You should find that the state of the art XD-15 ceramic bearings last longer than steel bearings, providing they are set up correctly and well maintained. If you are using regular hybrid ceramic bearings from Enduro you will need to ensure that they are cleaned and lubricated on a regular basis to last longer than steel bearings. Here at Aire Velo Bearings we follow Enduro guidelines and would recommend that your hybrid ceramic bearings are serviced every 6 months, otherwise you may find that they become subject to wear and tear faster. The team would also recommend that to get the most out of your bearings they should be thoroughly cleaned after long road rides or muddy cross rides. In the majority of cases bearings should last for a relatively long time, however once the grease has gone you will be looking for replacement bearings.