Park Tool Spoke Tension Meter TM-1

Spoke Tension Meter
The TM-1 Tension Meter accurately and reliably measures the absolute tension of each of the spokes in a wheel, as well as the relative tension between all the spokes in a wheel. Easy to use and priced affordably, the TM-1 works on nearly any bicycle spoke-no matter what the diameter, material, or shape. The TM-1 is for anyone building or truing wheels, diagnosing wheel problems, or assembling new bikes. It's a tool that belongs on every workbench.
NOTE: The TM-1 Tension Meter includes a printed table to convert tension reading to kilograms force. Because of new and varied steel bladed aerodynamic spokes, there is a webpage that acts as a chart calculator for steel bladed spokes not on the table. See the TM-1 Tension Meter Bladed Spoke Calculator here.
Also see the Wheel Tension Balance web app. This page will help the user quickly convert tension readings to kilogram force pull, and also provide a graphic chart of relative spoke tension.