Intro: How to Rebuild a Bicycle Front Hub...at TechShop!
This is a quick and easy guide to making those crunchy, loose, dirty, slow wheels feel like butter again! It'll take around 20-30 minutes for the beginner and faster once you get the hang of it.
A few things you'll need:
-Gloves (it gets dirty)
-Extra latex glove
-Cone wrenches that match your hub. Most are 13mm and 17mm, but they vary.
-Toothbrush (preferably your roommate's)
-Towel (preferably a clean washcloth, but paper towels are probably best since it'll be ruined the moment you use it)
-A clean, open workplace where you can find loose bearing balls that shoot off into the nevernever
You'll need some kind of cleaner for the grease, but I left this out because you can use damn near anything. The bearing balls are stainless steel, so you're not going to hurt them. I've used WD-40 for as long as I can remember, but I used windex this time and it worked fine. Residue isn't a real problem because you'll wipe them down on the paper towel before you put them back in.
Step 1: Get in There!
Once you have the wheel off your bike and the skewer (if you have one) is out of the axle, you'll want to loosen up one side (it might already be loose if your wheel was a little wobbly) and take the lock nut, any spacers, and the cone off. There might be a dust cover underneath. Mine has one. You can just gently pop it out with a wrench, knife, toothbrush, comb, key, toothpick, fork, bullet, used tungsten electrode, etc.
The axle is not held in with anything except those cones, so once you start to loosen them up, the bearing balls can fall out. The dust cover helps, but not all hubs have them and even with them the balls can fall out. You'll want the wheel sitting on the table while you do this so the axle is always pressed into the hub.
Step 2: Getting to the Bearings
Once the nuts are off one side, the axle will fall out the other side. Be careful with this and do it over a towel. The ball bearings might (probably will) fall out and if they hit anything hard they'll bounce to kingdom come and you'll have to sweep your workspace for days before you find it.
The nuts on the other side of the axle do not need to be removed, so it's a good idea to take your cone wrench(es) and tighten the cone and nut together to make sure they stay put when you reassemble the hub.
Step 3: Cleaning
Remember that extra latex glove? Once you get the bearing balls out, you can put them into a finger of the glove and fill it with a little bit of WD-40 or windex or something. A solvent is best because you want to get that heavy grease off along with any dirt particles, but with a bit of soap in it will probably do the trick. As long as you pour them onto a clean washcloth or paper towel and rub them enough, you'll get them plenty clean. This isn't Lance Armstrong's bike.
Now wipe the insides of the hub off with the towel and spray something in there and go at it with the toothbrush. Some will be dirtier than others, but as long as you don't have a bunch of pitting in there, you'll be able to clean it off just fine.
Do the same with the axle and cones and such. While you have it apart, why not make it all purty and shiny!
Step 4: Greasing
Now that the parts are all cleaned up, grab that grease and put a bead around the channel. It doesn't need to fill it up completely, but grease is cheap and too much is WAY better than too little. So err on the generous side.
Do this to both sides so that it's ready when you get the bearing balls in on one side. It's difficult to grease the inside when the axle is in there, and once you put that axle in, you don't want to take it out.
Step 5: Axle and Bearing Ball Replacement
Since the grease is in there, the balls will stay put as long as you squish them in a bit, so carefully (CAREFULLY) pick up the balls one at a time and put them in there. Again, dropping them will ruin your day. You'll probably never find them and you'll have to go online or find a kind bike shop to hook you up with another set. You can't replace just one, and they're not something found in any old hardware store. Also, they're not super cheap.
Since you are just putting your old ones back in, you have the right number, but just to be sure the person before you did it right, make sure there isn't very much space between the balls once they're all in. The amount in there should be the max allowed. If you add one more, they won't sit right in the cup. Make sure you're using exactly half the bearing balls you have on the table. Both sides of the hub should have the same number.
Now's the time to put a dust cover in there if you want. If yours aren't in very good condition (or not present at all), don't worry about putting it back in. I have hubs with and without dust covers and they both do just fine. If you're some extreme mountain biker who rides through dusty trails every ride, it might help, but hubs were doing fine for decades without them.
Now, take the axle, put a bit of grease on the cone, then slide it in there. Don't whack the bearing balls and knock them loose.
Step 6: Other Cone
Now that the axle is in there, hold it in place with one hand and turn it around. You're holding the bearing balls in there on the opposite side, so don't let it fall out. I like to place it on the table so I can use both hands. Now you can just toss the rest of the balls in the greased up cup because the axle will keep them from falling through the hub.
Thread the cone on there and put some grease on it. Hand tighten it down until it stops, then back off a quarter turn. Now we're at the toughest part!
Step 7: Fine Tuning
This is the part where you really need practice to get it right. The cones need to be spaced PERFECTLY to ensure the bearing balls are not being squeezed in their tracks, but there can't be any extra space for the bearings to wiggle around. I hand tighten it, then back it off (not more than a quarter turn) until the axle wiggles around in the hub just a teensy tiny bit, then lock it down with the lock nut using the cone wrenches. It helps to have the other side in a vice if you have one. This allows you to use both hands on the two wrenches and the axle won't turn. Once you lock it down, take the axle and turn it with your fingers. It should turn very smoothly with very little effort, but not wiggle at ALL when you try to move it around. This takes practice and should not be done carelessly. You can ruin your hub if this is done too tightly or loosely. If you can't get it just right, now's the time to ask for help. The hub might be worn beyond repair.
Since you're using all the same parts and you didn't move the lock nut and cone on one side, this shouldn't be a problem, but it's a good idea to check anyway: the axle should be sticking out of the hub on either side about the same amount. This is important because each side needs to be sticking out enough to bear the load from the frame dropouts, but if either side is sticking out TOO much, the skewer won't tighten down onto the frame. This is less of a concern if you have a solid axle and nuts.
Congrats! You conquered your first hub! The rear hub is tougher, but only because of the spacing and placement of the cones along the axle. If you figured the front hub out, the rear is totally doable.
I did this at TechShop San Jose!