When to Replace Bearings in a Bicycle

Having an enjoyable bike ride is oftentimes dependent on your equipment. The various bearing systems in your bike deserve your attention.

Whisping

One of the most common bearing problems is a "whisping" sound coming from the wheels. This is caused by a flat-spot in a bearing, and it can lead to scratches in the racer the bearings are held in. Replace all bearings because it is nearly impossible to tell which one is bad.

Water

You may have to replace the whole bottom bracket if it gets too wet.

Any time your bearings are completely immersed in water (like when riding through a deep creek)--then left to sit for a day or more without being overhauled and re-greased--they will have to be replaced. Rust, no matter how insignificant looking, always ruins bearings.

Gravely sound

a dirty headset, filled with gravel

If you spin the bearings near your ear and hear the sound of gravel rubbing, there is probably sand in your bearings. Sand will pock-mark metal and can lead to flat-spots. It also causes extra drag and prevents the bearings from moving freely.

Sticky spot

When spinning or turning the cranks, wheels or headset, you might come to a sticky spot. This may be caused by an ovalized headset, a bent frame, a bent axle, or bad bearings.

Frozen hub

If the thing that is supposed to spin doesn't move--or has a very hard time moving--check to make sure the hub that encases the bearings isn't too tight. If not, then your bearings will need to be replaced.

Brown watery grease

If you notice watery grease leaking from your hubs, that means water got in and is rusting your bearings. They will need to be replaced.

References

• Sheldon Brown, the bike guru
• Park tools how-to site