It’s so easy, these days, to establish the exact spoke length for any wheel. Just visit one of the Web’s many free calculation sites (DT’s, for example). But it wasn’t always so easy; in fact, the correct lengths were hard to discover, closely guarded secrets. For more than a century, wheel builders relied on charts and notebooks filled with observations. That’s the wheel world I entered in the early 1970’s, and here’s a glimpse.
For those of you who don’t build wheels, let me mention that the spoke length needs to be within a millimeter, less than 1/3 of one percent accurate. Otherwise you run the risk of too long (pops your tire) or too short (unsightly and weak) spokes. Compounding the task, manufacturing tolerances of rims, spokes, and hubs vary and they stretch and deform during building. With such a moving target, a tiny error in length calculation can become a time consuming failure. Here is the basic mathematical formula for spoke length determination: Read more →