[header] How to grease bicycle wheel bearings [title] Get some good, flat, open wrenches. [step] Make sure they are in sizes 13 mm and 15 mm. Those are the most common sizes. 
No other size wrench will work, but any type of adjustable wrench will do for the locking nut. [title] Put the flat wrench on the bearing cone between the hub and the locking nut.