Wipe out the bearing recesses in both hub flanges, making sure that the flange with the etched ZIPP logo has its circular wave spring fully seated in its groove in the base of the bearing recess.
Wipe a bead of thick grease around the mouth of the etched flange bearing recess.
NOTE: THE SEALS ON THE INNER SURFACE OF BEARINGS FOR ZIPP 145 MOUNTAIN HUBS SHOULD BE REMOVED. USE ALL OTHER BEARINGS FOR ROAD HUBS AS SUPPLIED WITH BEARING SEALS INTACT.
Insert the new axle (with bearing installed on the one end) into the non-etched flange. Support the hub, then press the bearing fully into place by its outside diameter only. A thin piece of 7/8" outside diameter tubing or a bearing press tool should be used along with a press or mallet.
Turn the hub over, then place the remaining bearing over the end of the axle protruding from the laser etched hub flange. Push the bearing onto the axle by hand, making sure that the bearing is centered over its flange recess.
Press both bearings together by their inside diameters only. This can be done by installing the axle end caps and quick release skewer, then fitting dropouts or washers into place outside of the end caps and tightening the skewer until the bearing are fully seated onto the axle. Remove end caps, reinstall rubber outer seals, then reinstall the end caps.