London Fixed-gear and Single-speed SJS Cycles

Most newer bicycles come with "caged" bearing balls-the balls are held in a metal or plastic retainer. This makes it easier to install the balls, but usually at a cost in performance. A standard three-piece type bottom bracket takes 11 loose 1/4-inch balls per side. Most retainers hold fewer balls, so each ball and its contact points with the cup and cone are more heavily stressed. This causes higher friction and more rapid wear. If your bottom bracket came with retainers holding fewer than 11 balls, I strongly recommend that you replace them with loose balls. This is not really difficult to do. if you know how.
The frame should be lying on its right side, with the fixed cup and liner installed. Squirt plenty of grease into both cups.
Set 11 balls into the adjustable cup. Drop the shorter end of the spindle into the cup, and it will hold the balls in place even if you are using a thin grease. Holding the adjustable cup and spindle as a unit, turn them over so that the cup is on top. Set this assembly aside in this position, supported by the spindle. (A convenient place to put it temporarily is into the right crank: the chain wheel will prevent it from falling over.)
Next, stick a finger up through the hole in the fixed cup to keep the balls from falling through. Drop 11 balls down into the cup and arrange them in a circle around your finger.
Then, pick up the spindle (with the adjustable cup already installed) and lower it down until it rests on the finger that is sticking up through the fixed cup. Lower it farther, until you can begin to screw the adjustable cup into the bottom bracket threads.
Keep the spindle supported from below until the adjustable cup is screwed well in, because if you release the spindle while the cup is very loose, the balls may fall out of position.