In depth: When to replace your bike’s chain
I recently wrote an article that discussed chain wear, and the life expectancy of a chain (see “How many miles will a road bike’s chain and cassette last?“) I received quite a few questions in response to that article, and so this morning I want to follow up with even more information on this controversial topic.
Wait, controversial? Yeppers. One might assume there would be very little debate surrounding a (ostensibly) simple question such as, “When should I replace my chain?” Of course nothing is simple on the Internet; if you so desire, you could easily spend dozens of hours reading and attempting to process the drastically different opinions on the subject of chain replacement. If you’ve got that kind of time to kill, I envy you. For the rest of us…
This article is meant to be a general guide (YMMV, literally), and I am basing the information presented on my own research, experiences and opinions after several dozen chain changes over tens of thousands of kilometers ridden (both MTB and road).
As most of you already know, bike chains have a finite lifespan. Your chain’s lifespan is affected by everything from your riding style, the condition of your bike’s other drivetrain components, the environmental conditions in which you ride and your drivetrain maintenance practices. In other words, it’s impossible to provide a universal answer to the question, “How long will my chain last?”
Over time, chains elongate. This is commonly called “chain stretch”, but that’s actually a bit misleading. The chain doesn’t actually stretch out from the incredible power you’re no doubt feeding into your drivetrain; what really causes a chain to elongate is the wearing down of the metal on the link pins as they rotate in the bushings. You can minimize chain wear and extend the life of your chain by adopting a few simple maintenance and riding style practices…
The first line of defense is to keep your chain and drivetrain clean at all times: Simply wipe down your chain with a clean, soft cloth after every single ride and lubricate your chain every 100-150 miles (and always after riding in particularly nasty weather conditions) with a high quality chain lube (I use and recommend Rock N Roll Gold). Also, give your cassette a good scrubbing at least once per week.
As for riding style, your chain will last longer if you don’t shift while the drivetrain is under load and you don’t cross-chain.
Okay, so how do you know when the chain needs to be replaced? Most manufacturers recommend that 10-speed and 11-speed chains be replaced when they reach 1/16″ to 1/8″ elongation.
There are a few different ways to determine how stretched a chain is, but the simplest method (I like simple) is to use the Park Chain Wear Indicator Tool (CC-3.2). The CC-3.2 is a binary (“go” or “no-go”) tool that will instantly tell you if you need to replace your chain.
Note that there are a couple versions of Park’s chain wear indicator tool. The old version, which is no longer being sold, is model CC-3.0. This model has 0.75 and 1.0 indicators, which are more suited for 9-speed and lower chains. 10-speed and 11-speed chains have tighter tolerances, and it’s recommended that they be replaced at 0.50 – 0.75. Park’s newer tool, the Model CC-3.2, addresses this by providing the more modern recommendations. Park also increased the length of the newer tool, making it more accurate.
I own the original CC-3.0, but at less than 10 bucks picking up the revised tool was a no-brainer. Here they are side-by-side (click to enlarge):
I choose to replace my chain when it reaches 1/16″ elongation (0.50 on the park tool). I could probably eek a little more life out of my chain, but the longer you ride on a worn chain the more damage it does to your other drivetrain components (specifically the cassette and the chainrings). Cassettes and chainrings are considerably more expensive than chains, and so I do what I can to minimize their wear. In addition to that, shifting performance is very important to me: I don’t want to have to worry about a worn chain causing shifting issues.
I replaced my road bike chain a couple days ago. I adhere to all the drivetrain maintenance “best practices” that I mentioned earlier in this article, and I got 2,700 miles (4,350 kilometers) out of this chain. That’s about average for me (click to enlarge):
Here’s the chain wear indicator right after the chain replacement. As you can see, it does not fit, so the chain is good (click to enlarge):
One other thing you can do to increase the lifespan of your chain and help ensure smooth, reliable shifting performance is to choose a good quality chain. I use and recommend the excellent KMC X10SL (click to enlarge):
A few words about cassette and chainring life: You should always replace your cassette with the chain (but not necessarily with every chain). As for how often you should replace your cassette, some say you should do it at every chain replacement, while others say you can get away with replacing it every 4th chain or more. I guess I fall somewhere in the middle of that range. I’ve always replaced my cassette every second chain, which is about 4,000-6,000 miles. I’ve never had any problems with chain skipping or bad shifts, and I was going to see if I could get 3 chains out of my current cassette. Well, wouldn’t you know it, I was experiencing some peculiar shifting issues and drivetrain noise even after replacing the chain, and so I decided to replace the cassette yesterday. Even with a fresh chain and cassette, the shifting issues and DT noise remain. I believe the problem is a worn or deformed chainring (I’ve detected a wobble on the big ring with my bike on the stand, bottom bracket seems fine), and so I’ve ordered a replacement. For what it’s worth, I got a little over 12,200 miles (about 20,000 kilometers) out of out of my chainrings/crankset (Shimano Ultegra 6750, 10 speed, 50/34, 175mm).