[Note: this is #1 in a series of tips to be published during 2009.]
Hexagon headed fasteners have dominated engineering for a century but bicycle wheels know better and every spoke nipple (well, 99.6%) in the world is square drive. Why? Even though square drive cannot transmit as much torque (twisting force), lower tolerances are required than with hex drive. Besides, if you plan to turn a fastener with just a two sided wrench (an open end wrench), then square drive is equivalent to hex for strength.
Since wheel building involves lots of separate adjustments and turning, it’s no surprise that open ended wrenches do the bulk of work. They’re easy on and off. Hence, square shaped nipples are dominant for bicycle wheels. My advice (Tip No. 1) is to use a three-sided spoke wrench whenever possible. See the difference:
Visualize each of these wrenches turning a square spoke nipple. Imagine the points of contact, the nipple being somewhat smaller than the wrench. Read more →