Chances are, you are riding around with little or no grease in your wheel bearings. Sad but true. Bearing manufacturers ensure robust future sales by skimping on the grease during assembly. (This is not BMWs fault BTW, before you hate.) But the good news is, those sealed bearings that make you feel all warm and fuzzy can be opened up and grease can be added. Its loads of fun. (Not really.) But it is easy, so lets get started. I am assuming that you know how/have the tools to get the wheels off of your bike. If not, then you are in trouble. Tools needed for loobin: Screwdriver or panel puller to remove the big external seals Thin, dull blade to pop bearing seal off Snap ring pliers Wheel bearing grease (preferably in a pencil-tipped gun) Front Wheel: Use the big screwdriver or panel puller to pop the big external seal out of the wheel: Now you can see the actual bearing. Take a DULL, very THIN tool of some type and CAREFULLY slide it between the rubber seal and the metal outer race of the bearing. My tool of choice here is a dull x-acto blade. Use caution not to damage the lips of the rubber seal. A light twist pops it right off. Dont be shocked if you see naked balls inside your wheels. Take the grease gun and aim it right between each pair, and shoot grease into the void between them. This puts it in the bearings path. FWIW, what looks like bearings here is actually the carrier, the bearings are actually behind it.) Leave some empty space in the cavity maybe aim for filling the bearing like 80%. Its no biggie if you put too much it just seems to ooze out the excess when things get really hot. By hand, snap the bearing seal back in nice and even, making sure the seal sits into the grooves in the bearing. Put the big outer seal pack in place flush with the outside of the hub. Sometimes these need a very light bump with a rubber mallet to set back home. Spooge a little grease on the lips of the seal where it runs on the axle or spacer. OK. Turn the wheel over, and remove the big outer seal. Uh oh, WTF is that stupid ring in the way for? Dammit. Just take the snap ring pliers, engage the holes and squeeze. Lift the snap ring out of the groove and set it aside. (The snap ring blocks you from pulling the bearing seal out.) > Grease up this bearing the same as the other - - just remember to put the snap ring back into place before you button things up with the big outer seal. Installation is the reverse or removal, right? Right. Rear Wheel: You have 3 bearings to do in the rear. Grab the sprocket carrier and pull it straight out from the wheel. Set it and the 4 cush rubbers aside for now. So, you know the drill now. Service that drive side bearing just like the front. Flip the wheel over, and meet your old friend the snap ring again. Time to do the bearing in the sprocket carrier. Pull the seal off, just like the others. Theres another snap ring in the way here, too. No problemo. Its good form to put grease on the axles, spacers, and the sealing surfaces of the rubber seals when putting the wheels back on your bike. Just wipe off the external excess once things are all back together to avoid a mountain of dust building up on everything. That way, things come back apart later without drama. Now start arguing about what kind of bearing grease is best, and whether its OK to use synthetic.