Ceramic bearings reduce drag in your hubs, and they do it in a dramatic way in comparison to the machine-quality cartridge bearings that come stock in most wheelsets -- even high end models. Ceramic bearings are measurably-and-devilishly round, and it's this roundness that gives them their rolling slickness. The reduction in mechanical drag you get by upgrading to ceramic bearings is no different than magically shedding ounces off your bike on a climb. For a given wattage, your speed increases. Period. According to tests the use of their ceramic bearings (including the specially formulated lubricant they roll in) gives you an added 20m-40m per 1km ridden. And keep in mind that mechanical drag is utterly unlike aerodynamics -- it becomes more and more critical the lower your speed is. According to these tests, the use of ceramic bearings decreases friction 22-fold. It's not personal, it's just physics.

Enduro offers a ceramic bearing upgrade kit for both Mavic and Zipp wheels. It's the best deal in town when you consider this upgrade alongside the cost difference between standard Zipp wheels and their ZedTech version (over $1,000 extra for an upgrade to ceramic bearings). We stock Enduro kits for the Mavic Ksyrium SL & ES wheelsets as well as for Zipp wheelsets.

The Ksyrium SL, ES, and Premium all use the same bearing kit. You'll get a total of 5 bearings in 3 sizes -- 2 for the front wheel, 2 for the freehub body, and 1 for the non-driveside of your rear hub. The Zipp kit is specific to their wheels vintage 2005 and later. It has 6 bearings total -- all the same size. (You can identify pre-2005 Zipp wheels due to the fact that they have 5 bearings of 1 size, and a 6th bearing of a different size.)