The chain fell off on a high-speed bike how to fix it

Switch configured incorrectly

This reason only applies to cycling vehicles with a gearshift switch. You need to make the adjustment of the rear derailleur as precise as possible.

Spontaneous gear shifting

Spontaneous gear shifting occurs in the same way as overshoot, but only after it the chain is on another smaller sprocket (higher gear). The reason for this is the sum of two reasons. the flexibility of the frame and the friction of the cables.


So what to do if a chain slips on a bike under load? The easiest option is to completely replace the transmission. However, it is not necessary to do this, you can determine the most worn out part of the system and repair only it.

It is necessary to change the stars only in extreme cases. However, this is a temporary solution. Eliminate the cause of the malfunction. replace, shorten the chain or adjust the switch.

Depending on the degree of wear of the part, the following repair methods are used:

  • complete replacement. in this case, breakthroughs can happen even more often at first, but over time, the parts will rub in, and the problem will be eliminated (while you do not forget to lubricate the unit so that it does not work for wear);
  • shortening. several links are removed using a squeeze;
  • the use of a damper. a device that increases the tension of the chain using rollers, preventing it from jumping off the sprockets.

Important! If there is no strong wear, but the chain still slips on the bike, you need to set the tensioner in the correct position and adjust the tension of the cables.

Partial open circuit

On one of the links, one of the chain cheeks flew off the pin or broke and, clinging to the caliper / stars, leads to its spontaneous jumping / reset / jamming.

A problem from the category of especially idiotic and obvious, however, I happened to face it for the first time not so long ago.

Remedy: Removing a defective pair of links from the chain using a squeeze, or replacing the entire chain.

Why does the bike chain slip?

Chain overshoot causes one of two unrelated phenomena. direct overshoot and spontaneous gear shifting.

The main thing to solve the problem is to determine what exactly comes from the two cases. Chain bounce is when it bounces under load on the top of the sprocket teeth.

After the jump, the chain remains in the same gear. This phenomenon is usually caused by wear on the sprocket or chain, or both.

Very often this happens when the chain is on the smallest star of the cassette, especially when it is used in conjunction with the smaller star of the system (which cannot be done). Also, sometimes overshoot can occur when the chain has bent links.

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Different disciplines and riding styles have different chain retention requirements. So in cross-country, just a front derailleur or an HB-star is enough, and downhill will already require a full set of dampers to securely fix the chain on the star. that either did not have sufficient reliability, or are very expensive, or require constant maintenance and replacement of parts.

Worn chain-cassette-system

A bicycle, like a car, has its own consumables. This includes all the components of the chain drive. Why do chains and stars need to be changed periodically? Due to wear:

  • The chain is constantly lengthening. This leads to an increase in the distance between the elements of one link (rollers). And the interval grows due to the boring of the axes (pins) of their seats.
  • The chain, lengthening, changes the profile of the teeth or, as they say, sharpens the teeth for itself. The wear mechanism is not closely illuminated, but as a first approximation it can be seen that there is plastic deformation of the teeth or the so-called “pulling out”.

chain, high-speed, bike

It is quite reasonable to ask why the chain slips on a speed bike only on some sprockets. The point is, everyone has their own favorite speeds. Usually there are two, maximum three small rear sprockets and one in front. The chain sharpens them, while others remain in the “novya” state, so the chain does not slip on unpopular gears.

Often a new chain jumps over the stars. This is due to the fact that it is installed on old stars. The teeth are stretched out for a larger pitch between the pins than on a new bike chain, which is why slip occurs. often the cassette is to blame, less often the system is also to blame.


The most accurate measurement tool. Adjust the inner dimension to 119 mm and measure the distance between the chain links. Based on the actual size, you can judge what to do with it:

  • 119.7-120.6 mm. You can continue driving.
  • 120.6-120.9 mm. Need to change.
  • than 120.9 mm. Replace with cassette.

Again, for Campagnolo, these control intervals are irrelevant and rarely monitored. Let’s say that it is customary to kill the same Record before the start of the overshoot (5,000-7,000 km), which means there is no need for control.

What to do if the bike chain falls off?

During the operation of the bicycle, the owner has to deal with a situation where the chain comes off during the ride. This situation is dangerous when driving at high speed, as well as in the process of screwing down a hill. Even if you use slip-on pedals with shoes to keep your foot from flying off the pedal, when the chain falls off, the cyclist can sprint over the handlebars or fall on his side. In this article, we will look at the main reasons why the bicycle chain flies, and also give practical advice on how to fix this breakdown.

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Elimination of breakage

Often, users are interested in what to do if the chain on the bike flies constantly. The repair algorithm depends on the type of bike. To eliminate the cause of scrolling the tract while loading the pedals of a conventional bicycle, you need to:

  • unscrew the rear wheel axle nuts;
  • pull it towards you;
  • ensuring the immobility of the wheel in relation to the center of the frame, tighten with nuts.

Performing the same work on a high-speed bike is more difficult. First, you need to measure the stretch of the chain. in the worn part, the size of the part does not match the pitch between the teeth of the stars. The result is a transmission failure. The level of production must be determined as follows:

  • using a tape measure, measure 24 segments of the tract on the stretched upper part (normal value is 30.5 cm);
  • determine the distance from 1 to 25 axis.

In this way, the degree of stretching is determined. Finding a malfunction affects the operation of the transmission. If the chain falls, the timely replacement of the part will avoid many problems in the future.

Results from 30 cm 64 mm to 30 cm 79 mm indicate that stretching has reached a critical state. In this case, install a new chain and sprockets.

To avoid problems, you should adhere to a certain algorithm. Instructions on how to put the chain if it flew off on a bicycle with several speeds:

3 Main Causes Of A Chain Drop How To Fix Them. Solving Bicycle Chain Problem.

  • place the link on a special squeeze so that the pin is in front of the axis;
  • slowly turn the handle until the pin is almost completely squeezed out;
  • install a new chain, starting to fix the switches with small stars;
  • put a chain on them, taking into account the location of the tension rollers;
  • aligning the links, clamp the chain, press in the axle.

After installing the chain, turn the pedals to check the operation of the element. It is advisable to do this with pressure. If all the steps are performed correctly, the chain on the bicycle will not fly off, sag.

To replace the cassette, you will need the following tools: an adjustable wrench and a wrench with a chain, a snap ring puller. Step-by-step instruction:

  • remove the wheel;
  • install the puller, making sure that the spitz is in the retaining ring;
  • make sure that the handle of the key with the chain from the cassette is located on the right side, and on the teeth of the star from below so that its links lie tightly;
  • put an adjustable wrench on the cassette remover, holding the whip to prevent the stars from turning; turn it counterclockwise;
  • unscrew the locking wheel;
  • dismantle washers, stars, laying them out in the same order to facilitate subsequent installation;
  • pins, grooves of bushings and stars are of equal dimensions, which facilitates correct installation;
  • put on stars and spacer rings in turn;
  • install the outer gear, screw on the retaining ring, check the correct assembly, tighten it up to the stop with a puller.
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To prevent the chain from slipping off the rear large chainring of the bike, it is worth installing a damper. Rockrings, which they are equipped with, protect the elements from damage while overcoming obstacles.

Step-by-step instructions on how to install dampers:

  • prepare tools: hexagons, rubber clamps, keys for removing bonks, carriage pullers, grease, squeeze;
  • dismantle the stars with connecting rods so that the large one is located on the middle one;
  • screw on the rockring;
  • determine the correct position of the roller;
  • tighten the bolts;
  • drip in the area of ​​the fastening bolts with threaded clamps;
  • install connecting rods;
  • put stars on the tract;
  • fix the rollers;
  • align the spacing between the inner pancake so that it coincides with the outer one; the chain should not touch the pancakes;
  • tighten the bolts all the way.

Installation must be carried out strictly following the instructions. Only then can the long-term operation of the transmission be guaranteed. Accelerators are mounted on some high-speed bikes.

How To Fix A Dropped Chain | What To Do If Your Chain Comes Off While Cycling

Chain damper

The second way to reduce the freedom of movement of the chain is to install a damper. This is a special frame through which the chain runs on top of the chainring and a roller that tightens it from below. When using this system, the likelihood of losing the chain drops several times, however, of course, there is a fly in the ointment. All this abundance of additional rollers and frames creates additional load on the chain and somewhat negatively affects pedaling.

Top bezel

Sometimes, for HB stars and bicycles that are not designed for very extreme riding, it is enough to install only one upper frame, it is much easier and does not interfere with pedaling. If you are using a front derailleur, the top bezel of the derailleur is perfect for the upper damper frame.