[deluz]

Originally Posted by Mark McM

Tension meters apply a side load to the spokes, and then measure the resultant lateral deflection. The three main factors that will determine the amount of deflection are the magnitude of the side load, the tension in the spokes, and the lateral stiffness of the spoke. However, minimizing the side load will decrease the amount of deflection due to the spoke's lateral stiffness, giving a more precise measurement of the tension. The downside of using a smaller side load is that you need a more sensitive and precise gauge.

The Wheel Fanatyk tension meter (which is based on the design originated by Jobst Brandt) uses a relatively small side load, minimizing the affect of the spoke's lateral stiffness. Another feature of the Brandt design is that it only contacts the spoke on on side, so the gauge reading measures only the deflection from the side load, and does not include the spoke thickness. In contrast, "scissors" type tension meters (such as the WheelSmith tension meter) contact both sides of the spokes, so the measurement includes both the spoke thickness and the deflection under side load. Scissors type tension meters can be thrown off by variations in spoke thickness, while Brandt type tensions meters are much less sensitive to variations in spoke thickness.

So, this is why Wheel Fanatyk tension meter can give precise readings over a wide range of spoke thicknesses and cross sectional shapes.

I don’t really understand the physics behind why a smaller side load makes the measurement independent of spoke shape and cross section, but I will just trust it is valid and get on with wheel building.