The trick to squeezing every last penny and mile out of a beater bike – that jalopy you ride every day and leave out in the rain – is to put in only the minimum time and effort required to keep it running adequately. In that spirit, here is a quick and dirty guide to greasing up and aligning your bike's wheel hubs.
Unlike converting a bike's bottom bracket, which is something you might have to do to turn your road bike into a single-speed, adjusting the hub on a run-of-the-mill bike wheel only requires special skinny (cone) wrenches, a vise, and grease. Let's dive in!
Here is a bike wheel that has been clamped between the jaws of a vise by one of its locknuts. (The thickness of the locknut and absence of a quick release indicates that this is a wheel you might find on a department store bike.)
And here is a closer look. A hub's adjustment is locked in place by tightening the locknut (top wrench) against the cone (bottom "skinny" wrench), both of which are threaded onto the wheel's axle. Turning the locknut and cone in opposite directions drives them apart, allowing them to be removed from the axle.
The cone (left) and locknut (right) have now been removed. You can see some ball bearings inside the hub. If the inside of the hub is relatively clean and the existing grease still glistens, I don't bother taking out the ball bearings and cleaning everything out; I simply wipe the cone clean and add fresh grease on top of everything.
Although there's no such thing as using too much grease, things can get messy when you thread the cone and locknut back on. Bear in mind that you will repeat this process on each side of the hub. So once you've greased up one side, tighten the locknut and cone against each other with considerable force, undo the vise and flip the wheel over. (The final hub adjustment will come later on, after you've greased the opposite side of the hub.)
When the hub is fully greased, we get to the final and most important step. Every hub has a Goldilocks adjustment: that sweet spot point between being "too tight," which means the wheel quickly grinds to a halt, and "too loose," wherein the rest of the wheel wobbles around the axle in an unsettling (and potentially unsafe) manner.
You start by threading the cone on the axle until it will go no further. Then, thread on the locknut by hand, until it is snug against the cone. Now, using the appropriate wrenches, tighten the cone against the locknut by turning it counter-clockwise against it. Unvise the wheel and check for play.
Getting a hub adjustment right the first time is as rare as hitting a hole-in-one in golf. Instead, it's preferable to start with the hub adjustment a tad "too tight," and then to gradually loosen it by clamping the wheel in the vise, undoing the locknut slightly, and backing off the cone counter-clockwise against it in small rotational increments of 5° - 10° at a time. (You can tell if you've loosened the cone too far with the wheel still in the vise by grabbing the rim and seeing if you are able to bounce it up and down slightly around the axle's axis.)
SUCCESS—a vise, a bit of wrenching, and a little grease will now allow you to keep squeezing every last bit of value out of your beater bike.