When it comes to stabilizers, stiffness is one of the most important features, but how do you even measure that? There are a few different ways to evaluate a rod's spine, which is how much a stabilizer or arrow shaft flexes when weight or force is applied.

Some methods are better than others. At RamRods archery, we developed a new method we call the Cantilever Spine Test of C-Spine for short.

Three point bend test

Before we got to the C-Spine, we started out with the three part bend test. This is a common method of establishing a stiffness metric and is used throughout the archery industry. It involves setting up a 30 inch stabilizer and balancing it on two points at each end. From there, you add a 25 pound weight to the center, hence the three points.

We felt that this test did not accurately replicate real-world performance when it came to determining the stiffness of a stabilizer, especially when it comes to tapered rods. When you shoot, you don't hold the rod from both ends and attach your weights in the middle. We needed a more accurate way to measure resistance to bending that was actually relevant to how a stabilizer is used. This is where C-Spine comes in.

c-spine test

In the workshop with a little tinkering, we developed a consistent and repeatable cantilever stiffness test.

We take a 30 inch stabilizer and lock down the proximal end, as if it were attached to a bow. Then at the distal end we hang 5 pounds or about 2.7kg. For reference, archers typically use between 4 - 25 ounces on the end of their front stabilizers, or between .25lb-1.5lb or 0.1kg - 0.7kg for reference.

With the 5lb on the distal end we measure exactly how much the tip of the stabilizer bends due to that weight.

A smaller amount of bend or deflection means a lower C-spine number, and therefore a stiffer stabilizer. Higher numbers indicate more bend in the rod, which means a weaker stabilizer. In the example below, the stabilizer on the left is stiffer, with the C-Spine at 260, and the stabilizer on the right is less stiff, with the C-Spine at 725.

Quick reminder, a stiffer stabilizer isn't automatically a better stabilizer. It all depends on your needs as an archer. A compound archer that shoots a high draw weight with a large weight stack at the end of their long rod might need a stiffer stabilizer like the Beast, but a recurve archer that doesn't shoot as high a weight can benefit more from a rod with higher C-Spine, such as the K2 2 or Ultra 4. If you're still unsure of which stabilizer is right for you, check out this breakdown of all of our rods or take this quick quiz to get a personalized result.