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| Tools needed:
Many older bikes are fitted with an open- bearing bottom bracket. To test the bracket for wear, take the chain off the chainrings and turn the crankset by hand in a pedaling action. If you hear grinding noises, or if the action feels rough, check the bracket. Then hold one of the crankarms near the pedal and push it inward -- more than 1mm of play means the bracket needs servicing.
The bearings may suffer more wear than those in cartridge-bearing brackets because they are not as well sealed and so let in dirt and water. However, regular cleaning and lubrication can drastically reduce this wear. A properly adjusted open-bearing bottom bracket is subject to less internal friction than many cartridge-bearing brackets.
If a bottom-bracket cup proves difficult to remove or refit, ask any good bike shop for help -- they will have special removal equipment and tools to clean and reinstate the shell threads.
Below: Parts of an open-bearing bottom bracket:
Maintaining an open-bearing bottom bracket
1. First remove both crankarms (see Steps 1-4 on this page).
2. Insert a peg wrench into two of the holes on the free cup.
3. Remove the fixed cup on the drive side of the bike by using a fixed-cup spanner on its two flats and turning clockwise.
4. Clean and examine the two cups now that you have removed them.
5. Grease the inside of the cups, press the bearings into the grease, and smear some grease on top of them.
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