How to Prevent Your Bike Chain From Coming Off
Nobody likes the feeling that they’re just spinning their wheels. And no one knows that feeling quite as well as a cyclist.
When your chain comes off in the middle of a ride, it’s an embarrassing moment — even worse than just spinning your wheels. Your legs fly into fast-forward, yet your bike is suddenly suspended in slow motion. You sink from confident rider to circus act in one fell swoop.
But it’s more than embarrassing; a dropped bike chain can be a serious problem. When your chain comes off in the middle of a group climb, you quickly become a hazard to any unsuspecting rider behind you. That’s why experienced cyclists know to yell a warning — “Chain!” — when their chain does come off.
Your bike chain coming off isn’t just a hazard to your physical and emotional well-being—it can damage your bike, too. If the chain gets stuck on the outside of your chainring, it could break the chain. More problematic, though, is when it comes off on the inside of the chainring and rubs against your bike frame. If this happens enough, it can wear a hole through the carbon fiber and ruin your frame.
It’s a common problem, and although there is a trick that often works to get the chain back on without stopping, it’s better to keep it from happening in the first place. Our good friend and longtime cycling coach Darryl MacKenzie has three ways to prevent your bike chain from coming off.
Your Chain Derailleurs Need Adjusting
As usual, Coach Darryl doesn’t mince words.
“When your chain does come off, it implies there is something wrong with one of two things: your bicycle or you,” he says.
Let’s start with your bike. One possible culprit for your dropped chain is your front derailleur. Over time — whether from general wear and tear, taking your bike in and out of the car, or the occasional fall — your derailleurs can become misaligned. When this happens on a bike with manual shifters, it will cause your front derailleur to move the chain too far in either direction and throw it off the cogs.
There are two screws on your derailleur that will adjust the maximum distance it can move in either direction. It’s possible to adjust these yourself, but it’s difficult to tell which screw to turn and which direction to turn it. That’s why Darryl recommends having a seasoned mechanic check your derailleurs and make adjustments as part of your regular maintenance routine.
Your Shifting Technique Needs Tweaking
The far more likely problem, though, is you. Well, your shifting technique, at least.
Many inexperienced cyclists aren’t aware that there are shifting habits that make it far more likely that they'll drop their chain. They do something called “cross-chaining.” This happens when you shift your chain to the far inside chainring and the far outside rear cog (or vice versa) at the same time.
In either case, the chain is at its maximum angle — instead of running parallel to the bike, it’s angled away from it. This creates tension in the chain, making it far easier to knock it off when you try to shift in the front. That extra tension can be enough to pull the chain just a little too far. It will also wear your chain down faster and make you have to change chains more frequently.
To prevent your bike chain from coming off through cross-chaining, think of your rear cassette in three sections — an inner third, a middle third and an outer third.
“Without a doubt, the best place to shift in the front is when the chain is on the middle third in the back,” says Coach Darryl. “When it’s on the middle third, you’re far more likely to get a precise, successful shift, than if you have it way over on either side.”
If possible, you should avoid getting cross-chained. But if it does happen, you need to adjust your chain in the rear before you shift in the front. Shift the rear chain positioning to the center third, then you can shift chainrings up front. This positioning loosens the tension on your chain and reduces the chances of throwing it off.
The Best Way to Make Sure Your Bike Chain Never Drops
In Darryl’s experience, electronic shifters are one of the most important upgrades you can make to your bike. They save your fingers a lot of work over time and clean up all the cables on your frame. But, even better, their precision makes it nearly impossible to drop your chain. Like a tensioned leather bike saddle, they’re well worth the investment.
Dropping your bike chain can be frustrating and embarrassing, but now you know how to make sure it doesn’t happen. Keep these things in mind and you’ll never feel like you’re just spinning your wheels again. That is, except when you’re really spinning them.
Look for more insights from Coach Darryl over at his website.