Bearings wear for a variety of reasons; by far the biggest culprit is contamination. You can prolong bearing life by not power-washing or hosing your bike off. Water sitting in your BB shell will eventually contaminate your bearings so be sure to drain and dry your frame after wet rides.  All of our BB bearings are easily serviceable, so we recommend cleaning and re-greasing them a few times a year dependent on conditions. If things go to hell in a hand-basket quickly, we offer a 1 year no questions asked warranty on all our bearings, so we've got you covered.