Why does the chain fall off?
Single speed bicycles with no gear shifting function rarely have chain drop. The only bicycles that fall off the chain are road bikes and MTB bicycles.
The reason for chain drop is simple: shifting gears = dropping the chain. The word “derailleur” is derived from the French words “de” (negation) and “railleur”. The word derailleur is derived from the French words “de” (negate) and “railleur”, which means “to drop the chain from the rails”.
In other words, shifting gears on a bicycle means temporarily dropping the chain from the gears to change gears, and if the gear shift does not go well, the chain will fall off.
How do I prevent the chain from falling off?
If you have front shifting
If your bike has a front shifting function, the front derailleur will play a role in preventing the chain from falling off.
If you are still experiencing chain drop, adjust the following points. 1.
- adjust the front derailleur
Adjust the length of the chain.
- replace the chainring
The basic maintenance is to adjust the front derailleur and chain length, but if the chainring is worn out, replacing the chainring will also prevent the chain from falling off.
Chain drop is also more likely to occur at the timing of front shifting. This is especially common when shifting the front gear with the chain tucked in. When the chain is tucked, the chain is slightly off the chainring, and chain drop is more likely to occur.
When shifting the front gear, try to use a gear combination that is not tucked to prevent the chain from falling off.
If you are still experiencing chain drop, try installing a chain catcher.
There are several chain catchers made by third parties. There are several third-party chain catchers available in different shapes and sizes, so it is best to choose one that fits your frame and front derailleur.
In some cases, the front derailleur needs to be removed to install the chain catcher, so if you cannot do the maintenance yourself, ask a pro store to do it for you.
For front singles
For front singles, there are several measures you can take.
- install a chainring guard
- replace with a narrow wide chainring
Chainring guards are often installed on front single production cars. Since the chain is sandwiched between the two sides of the chain, it prevents the chain from falling off almost 100% of the time.
On the other hand, road bikes and other sport bikes use narrow-width chainrings, which have a mechanism to prevent the chain from falling off.
Chainrings on bicycles with normal front shifting are designed to “drop the chain easily” in order to shift gears. Therefore, if a chainring designed for front shifting is used as a front single, chain drop will occur more easily. Narrow-width chainrings are designed so that the chain engages the chainring, thus preventing chain drop.
We have seen how to prevent a bicycle chain from falling off.
There is no other way to prevent a bicycle chain from falling off except through “maintenance” and “operation”. Especially for bicycles with front shifting gears, it is difficult to prevent the chain from falling off 100% due to its structure.
If you are experiencing frequent chain drop, you should consult your local bicycle store.