This post is my humble attempt at an explanation of spoke tapers and gauges. This is a somewhat confusing topic but I’ll try to make it as clear as possible. It’s a bit of a read, but hopefully not too long.
Spoke Gauge refers to the diameter of a spoke. Many spokes have multiple diameters along their length, this is referred to as taper.
There are four primary types of spoke tapers used by wheel builders; straight gauge, double butted, triple butted, and bladed. Straight gauge spokes are a consistent diameter along their entire length. Double-butted (DD) spokes have two diameters, a wider diameter at the ends, and a narrow tapered diameter at the arm (middle portion between the elbow and the thread). Triple-butted (3D) spokes have three diameters, a wider diameter at the head, a narrower tapered section at the arm, and a third diameter at the threads. The diameter at the threaded end of the 3D spoke is greater than the tapered section, but narrower than the head section. A bladed spoke starts its life as a round spoke, but then it’s middle section is worked flat. Bladed spokes offer some advantages in aerodynamics and loadability, and they look pretty cool too.
Spoke Gauge describes the diameter of the spoke, although many people simply refer to spokes by their diameter in millimetres these days. Below is a breakdown of some common spoke gauges and their metric equivalents:
13 Gauge = 2.3mm
14 Gauge = 2.0mm
15 Gauge = 1.8mm
16 Gauge = 1.6mm
17 Gauge = 1.5mm
When referring to a tapered spokes profile it’s typically described by its diameters. For example a Sapim Race double butted (DD) spoke has a profile of 2.0/1.8/2.0. This gets a little trickier with triple butted (3D) spokes that feature three diameters. The Sapim Force is a 3D spoke with a profile of 2.18/1.8/2.0. Bladed spokes feature round sections at the head and thread ends, and a flat or ovalized profile section in the middle. The Sapim CX-Ray is a j-bend bladed spoke with superior fatigue resistance. It has a profile of 2.0/(0.9x2.2)/2.0 mm. The bracketed section refers to its thickness of 0.9mm, and width of 2.2mm, at the bladed section.
In spokes, as in every other aspect of cycling there are exceptions. One of these exceptions is the single butted spoke. Single butted spokes are designed for high load applications like tandems and e-bikes. They feature a wider profile at the head section that quickly tapers to a narrower section for the remainder of the spokes length.The Sapim Strong is a single-butted spoke with a profile of 2.3/2.0.
There’s a wide variety of options available when choosing spokes for your wheels. By understanding the spoke properties you can better decide what works best for your application.