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Classic chain checkers like the Park Tool CC-2 and CC-3.2 have been around forever, but they're not cutting it anymore. If you've been measuring your SRAM Flattop chains with the same chain checker that's been kicking around your toolbox for the last decade, you may not be getting a correct measurement. In this article, we'll explain exactly why that is, and show you the tools you need to know exactly when to send your chain to the metal recycler.
These old friends have served us well, but they aren't going to cut it for T-Type chains.
SRAM Transmissions have been around for a few years, and now that riders have been turning those cranks over thousands of miles, it’s time to get the bike in the stand, and do some service. With a brand new design, SRAM Flat top chains require slightly different tools to measure wear, and considering how expensive some of these Transmission components are, this is a job worth doing right. If your chain wears out and you don’t replace it, that’s the fastest way to destroy a perfectly good cassette and chainring, costing you tons of money in new components. But if you replace your chain too often, then you’re spending more than you have to on new chains! Nailing the timing on replacing your chain is the number one way to make your cassette last a super long time, and as a bonus, your shifting will stay super crispy. So let’s explain how to know when to replace your T-Type chain.
There are tons of chain checker tools that will show you exactly how worn your chain is, and there are a couple main styles out there. You’re probably familiar with this classic Park Tool CC 3.2 chain checker that drops straight into a chain, quickly letting you know if your chain is worn out. Or this park Tool CC 2 chain checker that swings in to measure how much your chain has stretched. Because flat top T-Type chains have a unique design, not every chain checker will give you an accurate reading, and believe it or not, neither of these classic tools will actually work. To check a T-Type chain for wear, you need to use one of the chain checkers from SRAM’s approved list. I’m sure the list will grow in the future, but for now, there's the Pedros Chain Checker Plus II, the Park Tool CC-4.2, and the SRAM Chain Wear Check Tool. You’ll notice that all of these chain tools use a one-piece design, and have three prongs hanging off them. Pedro's option has a chain holder on the top side, making for easy quick link usage, but they all check chains about the same. Let me explain what’s going on here, and why you need one of these new school chain checkers to measure your flat top chains.
The new guard: SRAM Chain Wear Tool, Park Tool CC-4.2, Pedro's Chain Checker Plus II
SRAM’s T-Type chains use slightly larger diameter rollers compared to other mountain bike chains. When I say slightly, I mean you can barely see a difference when you measure them on some calipers. But the numbers don’t lie, and the T-Type rollers are a fraction of a millimeter larger diameter than the rollers on a standard Eagle chain. Believe it or not, that tiny little difference actually changes the whole equation. So while each T-Type link is the standard half inch from the center of one roller to the center of the next roller, each roller is slightly larger.
Not only does that throw off our chain wear measurement, but it also explains why SRAM is so adamant about using T-Type components together as a whole ecosystem. The cassette, chainring, and even derailleur pulleys are specifically designed around the geometry of the T-Type chain, and they need to work together to work correctly. But why does roller size matter when checking chain wear? To explain that, let’s take a closer look at what these old chain checkers are actually measuring.
All of these “older” chain checkers have one thing in common, and it’s which sides of the roller they’re measuring. Both the CC-3.2 and CC-2 chain checkers measure from the left side of a roller to the right side of another roller. Or vice versa, depending on how you’re looking at it, but the point is that the points they’re measuring to are not on the same sides of the rollers. These tools will only get an accurate measurement when the rollers are the exact size they’re designed around, and they have no flexibility to accurately measure a chain with different size rollers, whether that’s larger or smaller. To get around that, a new breed of chain checkers has been developed. These new school three prong chain checkers are agnostic to roller size, and their only requirement is that each link is the standard half inch in length. A rule that all mountain bike chains abide by.
All of these new chain tools from Park Tool, Pedro’s, and SRAM measure the distance from the right side of a roller to the right side of another roller. By measuring the same side of the roller, these chain checkers will give you an accurate reading on all mountain bike chains regardless of roller size. If the rollers are microscopic or fill out the entire half inch link, these chain checkers will be able to tell you exactly how worn your chain is.
To get an accurate reading, an additional prong has been added to the equation. That third prong is used to put tension on the chain, and is integral to getting an accurate reading. The old style of chain checkers could put tension on the chain by pulling the chain apart at two ends on opposite sides of the rollers, but with the new checkers measuring the same side of the roller, they need a helping hand to add some tension.
All of these T-Type compatible chain checkers function pretty much the same. I mean, they all look about the same, so I guess that’s not too surprising, but let me show you how to use them. You’ll start by inserting the middle hook and the adjacent prong into your chain. Make sure the hook is on an inner link, and then pinch the chain and tool together. That pinch puts tension on the chain, and is the trick that lets us get an accurate measurement, so make sure to hold that tension as you drop the third prong into the chain. If that prong hits the roller, then your chain is not worn enough to register on the tool, but if it drops into the chain, then you’ve got some chain wear. Make sure you don’t have the quick link in the section that you’re measuring, and measure the chain in a few places to double check that you’ve got it right.
This SRAM chain checker only measures for .8 percent stretch, while this Park Tool chain checker measures for .5, .75, and 1 percent stretch. SRAM recommends replacing T-Type chains at the .8 percent mark, hence why that’s the only wear indicator on their tool, but more frequent replacement isn’t a bad idea at all. Replacing chains at .5 percent is good practice for preventative maintenance, and is going to ensure your cassette lasts as long as possible. Your cassette and chainring can definitely survive if you wait until replacing at .8 percent, but I always try to replace my chains when they get to .5%. When they wear to that point, chains get a lot louder, and the shifting performance definitely starts to degrade pretty noticeably. I bought this SRAM chain checker before realizing that it actually only measures .8%, so now I need to get myself a Park Tool one to actually follow my own rule.
A tip for buying T-Type chains and chains for any drivetrain is to always splurge on your chain. As you can see here, I've got a standard Eagle 90 transmission, but I upgraded to the X0 chain because it's actually better value than the GX chain. The X0 chain costs twice as much, but I've found that they last more than twice as long, and run a bit smoother throughout their whole life. I also prefer running a steel chainring over aluminum because they last way longer, and they're way cheaper, which is the definition of a win win.
Again, I want to reiterate that these T-Type approved chain checkers also work on all other chains, so if you’re picking up a new chain checker for whatever reason and you don’t have a SRAM Transmission, I would recommend getting this Park Tool CC 4.2. It’s what we use in our service department, and it’ll work great for checking all mountain bike chains. Plus, if you ever own a bike with Transmission one day, then you’ll already have the right tool for the job.
