What are the issues with measuring chain wear? Well, there are several, the most important being the difference in diameter of SRAM's flat chains found on most of their modern drivetrains. The rollers on these chains measure 0.010" (0.254 mm). That doesn't sound like much, but when you do the maths to convert this to a wear percentage over 5 links, it represents a difference of 0.2%. When we replace chains with wear between 0.5 and 0.7%, that 0.2% can easily make the difference between replacing a single chain and replacing an entire drivetrain. But wait, there's MORE! Most chain wear tools currently on the market are laser-cut metal. It's a pretty cool process that's great for making sheet metal parts, the problem is that the precision of this process isn't excellent at +/- 0.010" (0.254 mm). If you add the tool's error itself to the roller variable, it's possible to double the tool's error.

The Abbey Chain Wear Plate is our latest application of precision to cycling tools. We set out to build not only a tool capable of handling roller diameter variation when measuring chain wear, but also to measure lateral wear, which no one has bothered to do so far. Linear wear, or stretch as it's commonly called, is measured by locating both sides of the roller in a V-shaped notch that allows us to accurately locate the centre of the roller regardless of its size. Then you align the pin with one of the 5 holes at the opposite end. This also prevents roller wear from influencing the measurement. It's as simple as that.

To measure lateral wear, the chain must be removed from the bike. Then, simply pinch the chain against the boss and hold it vertically and see how far it sags. Anything less than 6 doesn't shift well and a new chain will improve shifting quality.

The other major issue we addressed with this tool is the precision of the tool itself. Most chain wear tools on the market are laser-cut, which is an interesting process that we use for parts like our Fit Kit and Stu Stick. However, it's not that precise, as the repeatability of these machines can be around +/- 0.010. That's simply not good enough for tools of this nature, to be frank. Instead, we made the decision to manufacture our tool from billet to give it the durability and precision this tool deserves. As we manufacture them in-house, we also have complete control over the process and are able to maintain tolerances as tight as 0.0002" (0.005 mm). Admittedly, this may be a bit excessive for the application, but it's not really that difficult to do if you truly care.