Doesn’t shift gears on a shimano bike

Important setup steps

There are three key stages in this activity, neglect or violation of the sequence of their implementation can result in damaged equipment or its expensive repairs. Therefore, it is necessary to perform them only in this order: pull the gearshift cable, make sure that the adjusting screws are in the correct position and adjust the tensioner itself.

How to adjust the speed of the rear derailleur on a bicycle

  • To adjust the rear derailleur, set the chain to the second sprocket on the front sprocket. At the back we put the chain on the smallest star. These movements are done by holding the rear wheel in weight and manually cranking the pedals.
  • Problems can occur when switching to small star. The chain does not reach or makes strange noises. you need to adjust the limiter. There are two bolts at the back of the switch, each of which has a different function. One marked High (adjusts high gears, on a small star), the other Low (adjusts low gears, on a large star). It happens that there is no marking. Then we are guided by the external location of the bolts.
  • The High limiter is carefully twisted (fixing the stars of the desired size) until the problem disappears (unnecessary sounds, jumps, for example).
  • We tighten the Low limiter, also fixing the corresponding stars. Optimally tuned, the chain does not jump over the star and does not sound.
  • Checking the operation of the front derailleur (stars overlap).
  • Adjust the tension on the bike cable. The adjuster responsible for the cable tension is located on the shifters, or on the rear derailleur near the cable. If the settings are correct, the entire system should not make unusual sounds, and there should be no other obvious problems.

Adjusting the rear derailleur of the bike

Before starting to adjust the rear derailleur of the bicycle, make sure it is working properly, check if it is bent. The rear derailleur is more prone to impact and damage than any other part of a bicycle. This is due to its protruding location. When hit, the rear derailleur can bend towards the spokes, if it is installed on the cock, the derailleur may remain intact, and the cock can bend. If there is no cock, from a strong blow, the frame may bend. Be careful when operating your bike, try not to hit the rear derailleur violently.

To check if the rear derailleur or cock is bent, look at the rear of the derailleur frame. Two guide rollers must be in the same plane, one below the other, the chain between them must be strictly vertical, without distortions.

Do not attempt to straighten a bent cock by bending the speed selector in the opposite direction, as the derailleur frame is soft and may bend. In order to straighten the bracket, it must be removed from the bike frame. However, there is a special tool that is installed on the cock in place of the switch and allows you to straighten the cock on the frame, while being a kind of lever. At the same time, he has a pointer that shows how exactly the cock is aligned.

Be careful, on some Campagnolo derailleurs the frame is tilted (the tensioner pulley is farther from the wheel spokes than the idler pulley).

How to install the rear derailleur

Fitting a bike rear derailleur is not difficult and if you bought one to replace your old derailleur, follow these steps:

  • Remove the chain from the bike.
  • Flip the rear derailleur cable.
  • Dismantle the old crossover by unscrewing it from the cock and install a new rear derailleur.
  • Install the chain by correctly passing it between the derailleur rollers.
  • Adjust the rear derailleur as described below.

Possible errors when setting the rear derailleur

Question: What if I unscrewed the adjusting screw to the end, and the chain still does not switch to 1 speed lower?
Answer: Most likely you pulled the cable poorly by hand from step 4, or you did it with insufficiently tightened cable tension adjusting screws from step 3, and it is also possible that you did not pull the cable at the highest speed on the shifter described in step 1.

Question: I reached stage 7, but the chain was not on the smallest star why?
Answer: You may have pulled the cable too tight by hand in step 4, in which case try to loosen the cable tension slightly with the adjusting screw. If the chain still does not go to the extreme small star, repeat steps 1 to 4.

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High gear limitation (small star (H))

Loosely tightening the high gear stop screw can cause the chain to slide off the small sprocket and get stuck between it and the chainstay. And if the high gear limit screw is overtightened, it may prevent shifting to the smallest sprocket. But be careful, problems with shifting to high gears are rarely associated with the setting of the limiter, most often a bent switch or a cock is to blame, sometimes problems arise due to the difficult movement of the cable.

To start setting the end position, first move the chain to the highest gear position (large sprocket in front and small sprocket at the rear), unscrew the anchor bolt and loosen the cable, screw the adjusting drums on the shifter and on the rear derailleur lever to the end.

The essence of the setting is to set the speed selector rollers in the same plane with a small sprocket.

If you turn the stop screw “H” clockwise, the derailleur frame will move towards the wheel spokes, if you turn the screw counterclockwise, then the frame will move in the opposite direction, farther from the spokes.

After adjusting the position, tighten the cable tightly and secure it with the anchor screw.

Check if the switch and other components are in good condition.

  • Check if the cock or gearshift frame is bent. This is one of the most common rear derailleur malfunctions, when, with a side impact (or others, for example, when falling or touching a curb, etc.), the transfer frame or rooster is deformed. It is quite easy to check it We put the largest star in front, and the small one at the back (for example, 3×8 on 24 high-speed bikes), stand behind the bike and look at the position of the guide roller and the roller of the overhead tensioner. They must be in line and perpendicular to the ground.

Low gear limitation (large chainring (L))

If the low gear stop screw is loosely tightened, then the chain can come off the large sprocket and get stuck between it and the spokes, when the bike is moving, this can lead to the wheel blocking and falling, to the breakage of the spokes and the chain. And if you tighten the stop screw too tight, the chain will not shift to the large sprocket.

To set this end position, move the chain to the low gear position (small sprocket at the front, large sprocket at the rear), remove the adjusting screw “L” so that it does not restrict the derailleur.

The essence of the setting is to set the speed selector rollers in the same plane as the large sprocket. To do this, turn the stop screw “L” clockwise to the desired position.

Tightening the stop screw moves the derailleur towards the small sprockets, and unscrewing it counterclockwise moves it towards the spokes.

If the speed switch is set correctly, then during its operation you will have to adjust it only slightly, due to stretching or replacement of the cable.

Adjustment is made with an adjusting drum located on the shifter, on the speed switch itself (for mountain bikes) or on the upper part of the lower frame tube, near the shirt stop (for road bikes) of the cable on some switches there may be two drums. Adjustment can be done with any adjusting drum, it makes no difference which one to use.

Before tuning, shift the shifter to the highest gear (small sprocket), make sure the shift lever is in its full position.

Next, switch the shifter to the next speed and pedal forward. The chain should move to the next sprocket. If the chain does not cross, then the cable is not tight, turn the adjusting drum counterclockwise and the cable will be taut. Turn the drum half a turn and try changing the speed again. Be careful, if you overtighten the drum too much, the entire shift chain can shift, as a result, the gears will shift normally, but there will be malfunctions in the extreme positions. Therefore, first of all set up the first two switching steps.

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Technique: how to properly adjust the rear derailleur on a bicycle Shimano?

The procedure for repairing and debugging chain drive units should be carried out on a clean bicycle. Be sure to raise the rear wheel, for which they hang the frame on a hook or prepare a special stand.

Front derailleur adjustment

The front derailleur is less common than the rear derailleur. Bicycles with this device are cheaper. The front derailleur moves the chain to the stars of the system. Moving from side to side, he pushes the chain to the next star.

shift, gears, shimano, bike
  • Switch frame. A chain passes through it, this is the main element when switching speeds. She moves to the sides in front of the leading stars.
  • Parallelogram. the mechanism itself (speed switch). Includes spring.
  • Fastening to the frame.
  • Upper stop L.
  • Lower stop H.
  • Fastening the cable.

The main problem with the front derailleur is that the chain hits the frame when driving. You can fix this problem yourself.

Cables and shirts

Special attention should also be paid to cables with shirts. The shirt is the sheath of the cable. And special attention should be paid to them for the simple reason that if the cable or shirt is damaged, then at the most crucial moment it can break, and subsequently switching speeds will be impossible.

Therefore, they must be chosen very carefully so that there is no damage or traces of rust, and for each cable there is a different type of shirt. There are only three of them. a SIS lash, a SIS-SP braid and a twisted braid. Based on the selected cable, the correct shirt should also be selected. Otherwise, it may happen that the cable will rub the entire sheath, and it will fail.

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How to fix a shimano shifter that won’t shift

Fine tuning tips

  • you need to set the minimum speed, that is, at the back, the chain stands on the largest star, and in front on the smallest.
  • slightly loosen the tension of the cable and turn the screw L until there is a 1mm gap between the chain and the frame
  • we firmly fix the cable, before inserting it into a special groove.
  • we set the highest speed
  • adjustable with screw H the gap between the chain and the inner side of the frame
  • we check the performance
  • if the switching is tight, then we adjust with screws to the desired state
  • After all the manipulations, the bike should be washed and lubricated all parts (chain, sprockets, etc.)

Adjusting the forward speeds of the bike

You need to adjust the forward speeds in about the same way, there is nothing difficult there, and you can figure it out at the level of intuition, therefore, we will consider only some points. The chain runs along the chainrings with a metal stop that can be adjusted with two bolts. The principle is the same, so, as mentioned earlier, there is nothing complicated about it. And, again, in order not to suffer again with the setting, switch the speeds correctly, as described above.

The device of the spreader and the reasons for its functional failures

Before adjusting the rear derailleur on a bicycle, it is useful to find out the reasons for the malfunctioning of the mechanism. The essence of the problem lies in the following points:

  • Cable damage or lack of lubricant.
  • Violation of the integrity of the cable jacket.
  • Curved cock. fastening the mechanism to the bike frame.
  • Worn chain or sprocket cassette.
  • Jammed chain tensioner rollers.
  • Steering wheel gear shift problems.

Bicycle Rear Derailleur Adjustment

After we have eliminated all 5 possible problems with the rear derailleur, we can begin to configure it. I took a bike with a shimano rear derailleur and divided the whole setup into 8 steps:

On the shifter, we throw off to the highest speed (which corresponds to the smallest star on the block of led stars). We pedal so that the chain is on a small star. (now you understand why it is so convenient to work with the rack)

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I don’t see numbers on the shifter, but believe me the position of the indicator is on the “number” 9. Which corresponds to the smallest star on the cassette.

When adjusting the rear derailleur on the sprockets (front), it is best to place the chain where you use it most. This is usually the central star on a 3-star system.

Loosen the hexagon or bolt that holds the cable.

We twist it all the way, and then return one turn back all the adjusting thumbs of the cable tension, which are located on the switch and on the shifter (sometimes there is only one adjustment screw on bicycles, most often it is on the switch, less often on the shifter).

In my case, the cable tension regulator is located only on the shifter. The photo shows how I twist the lamb.

Bike won’t shift.Lets fix that

We pull the cable with our hand (it is not necessary to pull with all our strength, the main thing is that it does not sag and be stretched along its entire length) and tighten the bolt holding the cable.

Align the center of the derailleur foot rollers with the center of the smallest chainring on the bike. Some people remove the chain for stages 5 and 6 to fine tune them. I do not see the need for this, you can not shoot, especially if you have a switch that is not of the top level, such as shimano tourney, acera or alivio.

Actually, all this movement of the switch occurs using the adjusting screws with the letters “H” and “L”.

We turn the screw “H” with a screwdriver until the centers of the rollers on the foot of the switch and the small star coincide and go to the next step.

In the photo, I showed a red line, along which you can see that the switch roller is under a small star on the cassette, which means that the extreme position is set correctly.

We switch on the shifter to the lowest speed (number 1), which corresponds to the largest driven star. We twist the pedals so that the chain goes to the extreme sprocket. And also align the center of the foot rollers with the center of the largest sprocket. All this alignment takes place with the screw “L”.

On the shifter, the indicator for switching the speed to number 1, if there are no numbers in the most extreme position, which should correspond to the largest star on the cassette.

Essentially, the “H” and “L” screws act as end stops for your derailleur, which keeps the chain from flying off while driving and keeps you alive.

Then again we check and switch from the highest speed one step lower (if an 8-speed cassette, then from 8 to 7 speed), if the switch happened immediately, congratulations you set the switch! You can check the remaining speeds will also easily and clearly switch both up and down.!

The chain should jump to the adjacent speed. In my case, this is a 9 speed cassette. Switching from 9 to 8.

Adjust the distance from the largest star to the derailleur roller. This distance should be about 4 mm, if the distance is greater, the switching clarity will be reduced. The adjusting screw on the switch is responsible for adjusting this gap. By unscrewing the screw, the distance decreases, screwing it in increases. tuning is done on the largest star corresponding to the number 1 on your shifter.