As a bicycle insurer, we unfortunately see lots of written off frames pass through the office. A common way for the frame to break is damage caused by the chain coming off on the inside of the chainrings. With the chain off, the chain can become lodged between the crankset and the frame, causing considerable scratching and damage, especially if it's carbon fibre.
It's the worst feeling in the world, when you're pulling on a wedged chain that's only going to lead in a scratched bike. However 9 times out of 10 this issue is avoidable. To keep you and your bike healthy and happy, follow these 6 simple steps:
1) Keep the chain and cassette clean
A clean drivetrain is a happy drivetrain. By keeping your chain, cassette and chainrings clean, the chain won't stick as you pedal. People commonly refer to this as 'chain-suck', where the chain fails to release itself after passing over the front chainrings. Continuing to pedal will often see the chain come off of the inside.
An easy way to keep your chain clean is to use a specific chain cleaner. These cost around £15 a can be purchased from all bike shops. Paired with a good quality degreaser like this one from Muc-Off and your chain will come up sparkly new after every ride. It's good to thoroughly clean your drivetrain after every ride, however once or twice a fortnight (depending on how often you ride) should keep on top of grime build up. The group ride will look on you with shame if you turn up with a greasy chain...
Note if you go on an especially muddy or gritty ride you should get that chain clean as soon as possible!
2: Check Chain and Chainring Wear
The next step is to have a look at your chainrings and chain to see if they are worn out. Worn out components fail to hold the chain correctly when passing through the drive chain, which can lead to frequent chain drops.
To check your chain, it's useful to have a chain checker. These tools can be picked up for just a couple of quid, and determine how worn out your chain is.
If you don't have a chain checker, there is also the fabled 2,000-mile rule, that suggests you should replace the chain every 2,000 miles. However this is purely estimated, with different riders pushing different gears in different weather, you could easily get 2500 miles out of a chain, or fail to get 1,000.
This video from Park Tools, gives a good overview of when you should replace your chain:
Chainring and cassette wear can be visibly spotted. Have a close-up look to see whether the chainrings aren't rounded like they are in this picture below. A rounded chainring can dislodge the chain from the little ring and into the frame.
3: Adjust the front mech
Another thing worth checking is whether your front mech is aligned properly. The chain has to have the smoothest route possible, without the mech guiding it one way or another. This video from GCN tells you how to get your front derailleur running properly:
Whilst the front mech will likely be the reason for your chain dropping off of the front, it's always a good idea to have a precisely indexed rear derailleur too! Luckily the guys over at GCN have covered that as well:
4: Don't mash the pedals when the chain comes off
This step may seem obvious, but it is usually the cause of most frame damage and turns minor frame scratches into much larger scrapes.
Sometimes when you don't even realise your chain has come off, it can feel as if the drive chain isn't shifting properly, so a manic mash of the pedals entails where the chain gets wedged between the frame, then yanked out wrecking and snagging the paintwork. We've all been there.
The best thing to do in that situation is to keep aware of what's going on below and calmly get off to put the chain back on carefully. It's tempting when you see pro-cyclists chip the chain back on whilst on the move, but for mere mortals, it usually ends in tears.
5: Buy a Chain Catcher
A fail-safe method for preventing your chain from coming off is installing a chain catcher. These useful machined tools are attached to the front mech to stop the chain dropping off the inside (it's in the name). They've become increasingly more sleek and aerodynamic, perhaps as many pro cyclists have started to adopt them.
For races like Paris-Roubaix it's critical that the chain stays on, so if it's good enough for Sagan it's good enough for us right!
6: Clear stickers and Frame Protectors
As an after-thought, have you tried applying clear stickers to your frame to protect it from minor scrapes and scratches? They are remarkably effective at protecting from stones and grit that flicks up from the road, and might just help in the aid of a chain coming off.
Brands like Lizard Skins make thicker self-adhesive stickers that claim to serve as a 'protective shield against paint abrasion through outer cables, chain, installed bags, falling rocks and shoes'... and maybe your chain. It's a minor investment but could save you a lot of trouble and bother further down the line.
Here's a list of handy tools and recommendations to have in your arsenal: