15. How to Overhaul Wheel Bearings
Overhaul a hub, replace and grease the wheel bearings, and adjust the cones.
This tutorial will demonstrate how to grease your wheel bearings. For this job you'll need some rags, waterproof grease, and a 17mm open-end wrench. You'll also need a 13mm cone wrench for a front hub, and a 15mm cone wrench for a rear hub. When overhauling a hub, you should always replace the ball bearings. Most front hubs need 10 3/16" bearings per side, while rear hubs usually need 9 1/4" bearings.
Place the wheel on its side and slide a cone wrench onto the cone flats, and then loosen the left, or non-drive side locknut by turning it counter-clockwise against the cone wrench. Completely un-thread and remove the cone and locknut, and then slide the axle out from the right side of the hub.
Clean all of the old grease off of the axle and cones and remove all of the bearings from both sides, making sure to count how many you take out. Then clean the inside of the hub and carefully inspect both the cones and the inner bearing races. If there is any damage such as pitting then the cone and/or hub should be replaced.
Apply a generous layer of grease to both of the hub's bearing races. Then carefully insert all of the new bearings by pushing them down in the grease. When all of the bearings are installed, there should be about half a bearing space left. Cover all of the bearings with a layer of grease and lightly grease the axle threads.
Once the bearings are installed on both sides, carefully slide the axle into hub, making sure the bearings stay in place. Thread the left side cone, washer (if any) and locknut all the way on finger tight.
Now lay the wheel back on its side and place the cone wrench on the cone. Tighten the locknut against the cone and check to make sure there is no play in the hub, and that the wheel spins freely. You may have to loosen the locknut and repeat the procedure many times before it is correct. Quick release mechanisms tighten the cones slightly, so if you have a quick release axle, you'll have to leave a slight bit of play in the hub.
Re-install any seals and then put the wheel back on your bike. Finally, check the adjustment again by moving the wheel side to side at the rim. Again, there shouldn't be play in the wheel, and it should spin smoothly.