Servicing Sealed-Bearing Bicycle Wheel Hubs

By Jim Langley

Recently I helped a couple of my riding buddies with their rear wheel hubs. Hubs are the cylindrically shaped parts at the center of the wheels. The rear hub is among the hardest-working bicycle components because it spins whenever the bike’s moving, and, in most modern hubs, it includes the freehub that drives the bike when you pedal.

Both my friends had the same issue. They felt it when they removed the wheel and turned the hub axle in their fingers to check the hub. Instead of turning smoothly with a nice hydraulic resistance from the greased bearings inside, it felt rough. This makes it harder to pedal the bike and riding on it may damage the hub – not a good idea on an expensive wheel. So they called me for help.

Most modern wheelsets have easy-to-service sealed bearings

Here’s the funny part. Because there are so many different companies making wheels today, and such a demand for new designs every season, I barely knew as much about their hubs as they did. But, I knew that their modern low spoke-count wheels had sealed-bearing hubs, because almost all do. And, that told me that it would be relatively quick and easy to get their wheels running smoothly again. Here’s how I went about it, and how you can with your hubs.

Please keep in mind that I’m assuming your hubs are in decent shape to begin with. If you ride in the rain a lot and/or have tens of thousands of miles on your wheels with no service, you will likely need more work than the simple regreasing I explain here.

Basic tools and materials (different hub designs may require a few other tools)

—bicycle bearing grease
—cassette lockring remover for your cassette type
—12-inch adjustable wrench
—chainwhip
—cone wrenches to fit your hub
—metric allen wrench set
—pliers
—penknife or blade from a boxknife

Do a little research

When taking apart hubs it’s best to follow instructions, because some designs are tricky to figure out. It’s rare to get instructions when you buy a bike. But most big-name wheel makers have websites, and by searching their support or technical documents you can often find hub instructions. If so, print them so you’ll have a hard copy.

Tip: If you can’t find instructions online but you see a tech-support phone number, try calling and asking if they can provide the link to their instructions or if they can email them to you. You can’t always get a person on the line but the bicycle industry is better than most and sometimes you can, so it’s worth a try.

Steps for servicing your hubs

If you have the directions, follow them. If not, do your best Sherlock Holmes impersonation and figure your hub out. It may look like it’s one piece and won’t come apart. But, don’t be deterred. There are moving parts inside. So you know someone put them in there. And you also know there’s a way to get them out!

Plus, with sealed-bearing hubs there are no individual ball bearings to fall out and get lost, and no difficult bearing adjustments to make. All that’s usually required is removing the axle to get at and service the bearings, and reinstalling the axle. And, to do that, all you have to do is figure out how to get the axle out. The following steps work for most hubs.

• • Take the rear wheel off. Remove the rear wheel, quick release skewer and cassette (using the chainwhip, lockring remover and adjustable wrench).

Tip: Lay any parts that you remove down in the order they came off, or make a drawing so you know how they go back together again.

• • Remove the axle from the hub. Look closely at the parts on the axle’s left end. If you see wrench flats on the locknut on the end of the axle, and another part with wrench flats beneath the locknut, use cone wrenches to loosen and unscrew the parts, and you can then usually push the axle out of the hub to the right. If only the locknut has wrench flats, look inside the axle to see if it’s hex-shaped. If so, insert an allen wrench, hold the axle, unscrew the locknut, slip any other parts off it, and push it out. If there are no wrench flats, the end cap is probably a press-fit. Try twisting/pulling by hand to remove it, or protect it and gently pull it off with pliers. One of these approaches will usually work to disassemble the axle to the point that you can push it out.

Tip: On some hubs, the freehub body will come off when you push the axle out of the hub, so work carefully and pay attention to how it fits. There are pawls and springs in the base of the freehub that have to fit correctly in order to drive your bike, but it makes good sense if you look at it. If the freehub parts are dirty, clean them and lubricate them with a light grease or heavy oil.

• Find and open the sealed bearings. With the parts and axle removed, you should see the sealed bearings on either side of the hub. They’re steel cartridges with black seals. Put your finger in the center and turn to feel how dry the bearings inside are. To open the bearings, gently work the blade tip beneath the edge of the seal and twist to free and remove the seal, which is pressed into the cartridge. Careful! Don’t bend it. It may take a few tries. Be patient.
• Regrease the bearings and reassemble the hub. Once the seals are off, you’ll see the bearings inside the cartridge and can press fresh grease into them with your finger. Use enough to cover the bearing, then press the seal back in place, making sure it’s seated fully all around. Doing this pushes the grease into the bearing. Wipe off any excess grease with a rag. Then reassemble the hub and it’ll run smoothly again and be good to go for many more miles.