Use Tennis Ball Grips to Ease Soreness, Numbness

Step 1: drill a hole slightly smaller than a #8 stainless screw through the center of each nylon bar end plug
Step 2: use a 7/8 inch hole saw to cut a hole in each tennis ball
Step 3: press the tennis ball onto the bar ends.
Step 4: drill a single 1/8 hole opposite the 7/8 hole
Step 5: screw a #8 stainless countersunk ovalhead screw with a stainless #8 trim washer through the 1/8 hole into the predrilled hole in the bar end cap

Madden noted that in this last step that the bar end cap might spin inside the bar end and not tighten when you try to insert the screw. If this happens, you should remove the bar end cap and insert it into the tennis ball through the 7/8 hole, then hold it with needle nose pliers while tightening the screw. After that you will pound the whole assembly (tennis ball with bar end cap inside) back onto the bar end.

Madden offered this final observation:

"My bike was my pride and joy so it was a little difficult to add two peculiar looking tennis balls in a spot that is very noticeable. They work so well I will keep using them even, though they look ugly -- until I figure out how to get the same benefits from grips that are beautiful."