Fall is a great time to get out on your bike and enjoy a ride on your local prairie path and take in all the colors and brisk air fall has to offer. After taking a few final rides of the biking season it’s a good idea to check your wheel bearings for natural wear and tear from the summer months.
The bicycle is not a complicated machine. So it’s all too easy to neglect the hidden ball bearings which keep your bike moving. As, in any mechanical device, where two surfaces make frictional contact with each other, you have to minimize friction.
In many cases, a simple, well-lubricated bearing will do the job. In the more advanced ball bearing, however, the load is handled by a number of hardened alloy-steel balls, which are themselves free to move along a narrow circular race. In an ideal ball bearing, the load is concentrated at defined points between the balls and the ring raceways. The steel balls would be perfect spheres and therefore make direct contact with the opposing surfaces at two points, reducing the area liable to frictional wear.
In ideal operation, the balls are free to move in a rolling manner and any slight amount of wear which they undergo during the course of time will be equalized over the entire surfaces of the balls. The balls may ultimately become slightly reduced in size, but they will all be reduced equally keeping their spherical shape, so that the working efficiency of the ball bearing is maintained.
Generally, ball-bearings are not “perfect” in their proportions, and signs of wear occur after a time. A “perfect” ball bearing would need no lubrication at all. Since it is impossible to manufacture absolutely spherical hardened steel balls, a true rolling motion of the balls within their race cannot be guaranteed; and the ball-race itself always has variation – this variation increases with wear. So ball-bearings should be lubricated.
The best lubricant for a ball bearing consists of a medium-thin grease, filling the space between the rings, with the excess wiped away after assembly. Most normal bearing applications require approximately 30% of the bearing cavity to be filled. The steel balls will thus become covered with a thin layer of lubricant which will not only reduce frictional wear at their points of contact within the bearing, but will also help reduce the bearing operational temperature.
All ball bearings in a bicycle should be dismantled and examined at least once a year. The balls themselves are the first to show signs of wear and replacing them with new balls can be enough to make the bearing like new. But the slightest sign of pitting in the inner or outer ring means the entire bearing needs to be replaced.
Dirt and debris are also enemies of ball bearings and if not kept out, bearing failure is likely to occur. It’s important to maintain the seals or other coverings to keep dirt and debris out. Proper ball bearing maintenance will keep your bike rolling for many more seasons to come.