Snowboard materials and the boards design determine a board’s characteristics and performance. Snowboarders typically refer to how good a snowboard performs by the term “board feel”. Performance is important to all riders. So how do you figure how a board feels? What is flex?
To ask what “board feel” is or why snowboards behave the way they do is all about the snowboards dynamics. The characteristics of a snowboard such as board stiffness and the damping are related to performance. To correlate relatively vague qualitative descriptions of board performance, such as ‘soft’, ‘stiff’ or ‘stable’ with the quantitative measurements of board characteristics represented by stress, vibrations, frequencies, and damping ratio testing must be performed to detect the characteristics of a specific snowboard.
These tests help us draw educated conclusions about how the snowboard will perform. At Signal to help us solve this our main concern is the snowboard's overall flex. We measure this so that we can be consistent throughout a production run with a clearly defined calculation and process on how we measure “Flex” as well as pass this information along to our subscribers in an easy to use numbering system. Basically 1-10 on a scale 10 being a 2x4 piece of lumber.
To differentiate snowboards accordingly, Testing begins with two important characteristics: stiffness and damping ratio. These two characteristics are significant to how the snowboard will behave while you’re out shredding. Flexibility and vibration differs depending on the type of materials and the overall quality of the snowboard.
A snowboard does not have uniform stiffness throughout the entire board. Typically, the board is stiffer between the rider’s feet and more flexible towards the tips. In addition to our flex testing field testing also help us to provide actual information regarding a snowboards performance and response or “board feel”
How do we measure flex? What is it really?
There are 4 measurements when talking about board flex.
The most useful and widely used flex test is the Global flex test. This is the one you see people doing all the time in shops and on snow, you hold the board by the tip in one hand and push against the middle of the board with your other hand and the resistance is what you feel the more resistance the stiffer the board. We refer to this resistance as deflection and is measured in EI.
The remaining 3 measurements are the Mid flex, Fore flex and Aft flex. These are not easily field tested but are as equally important as the Global flex to calculate how a board flexes over all.
To measure each of these we use a flex machine with a deflection gauge and a flex calculator that combines the boards running length tip and tail lengths to formulate a calculation of deflection in each zone.
We start by laying the board base side up on a flat even surface. All our measurements are from the tail end of the board. We Mark the board base along the centreline at distances equal to:
- Aft Mark: Spec tail length + .25 x spec running length
- Mid Mark: Spec tail length + .50 x spec running length
- Fore Mark: Spec tail length + .75 x spec running length
We then use our flex machine to apply pressure with a 40lb weight in each zone listed above and the amount of deflection is then recorded on the deflection gauge. Once we have deflection numbers for each zone we then put those numbers in to a flex calculator to give us numbers for flex/EI. We then take the board for a spin on snow. If we feel like the board is too stiff or too soft in any of the zones we now have quantifiable numbers that can then be feed back to our engineers who can then manipulate the boards wood core profile/thickness and sometimes materials to give us the perfect amount of deflection for the boards intended use. Usually park boards have a softer flex so that they are easily manipulated or flexed while riding whereas all mountain boards are stiffer so that they will handle better at high speeds or in variable conditions. So, get out there and flex some boards then ride them to find your ideal mix of Deflection.