The falling bicycle chain it is a very common problem among those who use two wheels: sometimes the chain falls under stress, when pushing on the pedals or uphill, both with racing bikes and MTBs, other times the chain jumps even when it is new, and it’s never easy understand why the chain falls of the bicycle. In fact, there are numerous causes why the bike chain jumps while pedaling. Let’s try to understand them, identifying the reasons why the chain jumps from the crown or sprockets and the remedies to prevent it from happening again.
Why the bicycle chain falls
Generally speaking, the reasons why the bike chain jumps and falls can be grouped into 3 categories: wear, poor adjustment, damage accidental due to falls or similar. Let’s try to explain them in detail.
Rusty chain
It is the most banal and easy to identify reason why the bicycle chain jumps and falls: a rusty chain can also be seen with the naked eye and it is enough to observe it passing through the rear derailleur or over the sprockets to realize how its links do not fold naturally. A first attempt could be to lubricate the chain with bicycle chain oil, but if the rust is severe and the problem is not resolved, the chain must be changed.
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The chain is old and worn
Yes, too the bicycle chain wears out and when this happens it tends to stretch, struggling to match the teeth of the pinions or crown. Also in this case the solution is to replace the chain. If despite the replacement, the chain keeps jumping and falling then it is very likely that a loose or rusty chain has ruined the sprockets: to understand this you need an eye trained to observe the teeth, which if damaged have the shape of a hook.
A good way to understand if the sprockets are worn is to observe which ratios the chain jumps to: reasonably they should be the most used ones, unless they are extreme ratios which are always not recommended to use (large crown – large pinion; small crown – small sprocket, as explained here).
The chain links are stiff
If not all, probably some: just slowly turn the pedals backwards, rotating the crankset backwards, to see if there is a stiff mesh that does not pass well over the sprockets or in the pulley wheels. If the problem is not solved by lubricating the chain, you need to loosen the rigid links: if you are expert you can also do this by bending them sideways with your hands, but if you are inexperienced it is better to contact a competent cyclist.
The chain is broken
Not in the sense of broken but it could have been one of the cylindrical rollers broke, or it could have detached from the rivet: to understand this you need to check each link of the chain, with a specific gauge, and it is a complicated and time-consuming job to do. But if you have not solved the problem with the previous advice, you should also consider this hypothesis. If this is the case, the chain must be changed.
The rear derailleur is poorly adjusted or bent
The rear derailleur allows you to pass the chain from one sprocket to another, thus changing the ratios. If it is bent or badly adjusted or bent it will tension the chain incorrectly, causing it to jump or fall: to realize if the problem depends on the derailleur you need to rotate the pedals and the chain in reverse, checking that the chain does not get stuck. If this happens, the derailleur must be adjusted or replaced, and it is best to contact a competent cycle workshop.
Worn gear cables or sheaths
The problem of the chain jumping on a bike with gears could be upstream of the crankset, sprockets and derailleurs: also worn cables and sheathsfrayed, dirty or rusty tend to position the derailleurs incorrectly, which then puts pressure on the chain causing it to jump and fall. The problem can be solved by replacing cables and sheaths, which is not a trivial job and should be done by a cycle workshop.
The rear pulleys are loose
The rear pulleys, which keep the chain tensioned, can loosen, thus moving sideways and causing the chain to jump and fall. The problem should be solved by tightening the bolt that secures the wheel to the cage to the right tension, but it is a delicate job to do without pressing too much and it is better to have it done by a cycle workshop if you are not an expert.
Photo credits: CC Pixabay
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2024-06-06 07:36:55
#Falling #bicycle #chain
