by Jim Langley
Checking wheel bearings
This week’s subject was suggested by a reader with the handle “SJ,” who asked, “How often should wheel hub bearings be degreased and re-greased?”
It’s a great question because it’s tricky to evaluate the condition of wheel bearings and to know what to do about issues, too. Wheels can still seem to roll and spin perfectly fine even when there’s no grease in the bearings – or worse, the bearings are dry and binding so bad that you can barely turn the axle by hand when the wheel is off the bike.
To help, here are a few different ways to check your bike’s wheel bearing and some tips for how to proceed with repairs.
The “valve test”
A quick way to check wheel bearings is to lift the bike so that the wheel in question is off the ground. Then place the heaviest part of the wheel, which is usually the valve (or wheel reflector if you have these), at 3 o’clock. Now, release the wheel and see if the weight of the valve (or reflector) is enough to turn the wheel so that the heavy portion comes down to 6 o’clock.
You might have a tubeless wheel with sealant inside or a rim and/or tire that has a heavy portion you can’t distinguish. In that case, try raising three or four places around the wheel to 3 o’clock and letting go. Chances are that at one placement, the heavy spot will make the wheel rotate down when you release it.
Note that if a brake pad (rim or disc) is dragging even a tiny bit, such as caused by a slight wobble in the rim or rotor, this test may not work. So, check first by spinning the wheel and inspecting for clearance all around.
If your wheel turns from the weight of the valve or reflector, or simply from the heaviest part of the tire or rim, it’s a good sign that your bearings are not too tight or binding.
This test does not always work as well on the rear wheel as the front due to the additional drag of the cassette bearings. But it’s still worth trying.
If you find that the wheel turns stiffly when you move it lightly by hand, or even seems notchy or wants to stop on its own, it’s a sign that the hub has issues and needs maintenance.
Check for bearing play
Another easy and fast bearing test is to see if there’s any lateral (side-to-side) play. Test for this by holding the top of the wheel while it’s in the bicycle and gently pushing and pulling sideways to feel for movement of the wheel. In most properly adjusted hub bearings, there will be no noticeable play.
If there is a lot of play, it usually means that the hub bearing adjustment has loosened. Or in the case of sealed-bearing hubs, either the bearing(s) is worn out, or the grease inside the sealed cartridge bearings in these hubs has been all used up over time. When this happens, since the grease takes up space inside the bearing, it can result in play in the bearings.
Good wheels will pass both the “valve” and the almost-no-lateral play tests, and probably don’t require service yet.
Feeling for bearing issues
The best test for checking the condition of hub bearings is done by removing the wheel(s). With the wheel off the bike, it’s easy to hold the axle and inspect its parts and also turn the axle to feel the condition of the bearings.
To inspect the axle parts, try to turn them with your fingers to make sure all the parts are tightened against each other on the axle. Nothing should be loose or else this can cause play in the hub bearings and also lead to changes in the bearing adjustment, which can ultimately damage some hubs.
If the axle parts are all secure, turn the axle holding it between your thumb and forefinger, feeling how it turns. Don’t hold the quick release or axle nuts if you have these. Hold onto and turn the axle because it’s holding the parts in contact with the bearings.
Hub bearings in good condition will feel smooth when you turn the axle because the grease inside is coating the bearings preventing metal-on-metal contact.
Worn out or dry bearings will feel rough, metallic and dry. Sometimes they’re so dry that if you pull your finger fast across the axle you can make the axle keep spinning because there’s no grease inside the bearings to slow it down. You might also hear a ticking sound if you spin the wheel, which is the dry ball bearings falling into each other. These are all signs that you either need to regrease or replace the bearings.
Fixing cup-and-cone hub bearing issues
For standard cup-and-cone hub bearings, it’s not too difficult to disassemble, clean and regrease the bearings. It’s usually best to replace the bearings rather than to reuse the old ones (new ball bearings aren’t expensive). You should also replace any worn axle parts at this time.
On rear wheels, it almost always best to remove the cluster of gears (called the “cassette” or “freewheel”) before attempting to service the hub bearings. That’s because you may need to access parts on the axle that are hidden beneath the gears.
Removing the cassette or freewheel requires the right cassette removal tool, a large adjustable wrench to hold that tool, and a chain whip to hold the cassette from turning as you turn it with the removal tool to take the cassette off.
Cassette body bearings
Note that while there are bearings inside the cassette body (referred to as the “freehub”) and freewheel body, they don’t usually require service as frequently as hubs do. And with luck you might never experience issues. But this depends a lot of the conditions you ride in.
Tip: To ensure the cassette/freewheel bearings and hub bearings stay greased as long as possible, never spray water, lubes or degreasers from the side anywhere near these parts. This can happen, for example, when cleaning the chain and cassette if you’re not careful.
Fixing sealed hub bearing issues
For sealed cartridge bearing hubs, it depends on the make and model whether service is easy or complicated. Look for instructions on the maker’s website. On easy sealed hubs, you may need the right tools, but it’s usually not that difficult to knock out the worn sealed bearings (they are contained in cartridges, making the job easier) and pressing in the new ones.
On some sealed hubs it’s possible to work on the bearings with hardly any axle disassembly because the cartridges are in plain view (on the rear wheel, the cassette still needs to be removed). On these you can slip the tip of a sharp, thin blade beneath an edge of the black bearing seal to lift it out (don’t bend it!) and squirt fresh grease in.
When you press the seal back in place, it will push the new grease into the bearings, refreshing them. Unless the old bearings were damaged, this will keep them running nicely until the next time it’s needed. Since they’re so well sealed, cartridge bearings tend to stay clean inside. So you don’t always need to clean them. Pushing in fresh grease is all it takes to get good bearings nice and smooth again.
On difficult sealed hubs, special tools and bearings will be required. In some cases you may even need to send the hub back to the maker to have the bearings serviced and/or replaced. Or the entire wheel, since otherwise you’d need to remove the hub from it and have to rebuild the wheel! To do this, ask your favorite bike shop if they can provide you with a wheel box.
The instructions for hub repairs by the factory should be explained on the maker’s website, so look there before trying to fix the hub(s) yourself.
For more in-depth bearing care tips
Park Tool has helpful articles on hub maintenance. Here’s one that covers the basics of cup-and-cone and cartridge bearing hubs. Here’s another that goes in-depth on freehub service on a few popular brands of sealed hubs.
Finally, I want to give a shout out to the remarkable British Olympian Ron Hill, one of my heroes back in high school when I was more a runner than a cyclist. He was the main person who inspired me to start my current cycling streak.
Knowing about my riding addiction (like running, a healthy habit), RoadBikeRider founder Ed Pavelka forwarded a link to a Washington Post article about Hill ending his running streak because of heart issues at 78 years of age. Hill is now the current record holder with 52 years and 39 days in a row in the books, which is 19,032 days! Makes my 8,445 days of riding in a row seem silly. Bravo, Mr. Hill!
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s streak of consecutive cycling days has reached more than 8,000. Click to read Jim’s full bio.