How to replace a rear sprocket on a speed bike


Step-by-step instructions for parsing:

  • The bike is installed with the wheels upwards and is in a stable position. The bike must stand on a flat surface and not carry out additional movements that can adversely affect the removal of parts;
  • We remove the wheel located at the back, this can be done using a wrench of the appropriate size. The chain for parsing the star is removed in order not to interfere;
  • Use a whip to fix the cassette in one place, untwist the cassette itself using a puller put on the nut;
  • After that, we remove the plastic ring, which serves as a kind of protection and establish a further front of work (directly install a new one or try to clean and lubricate the parts).

Bicycle sprocket design

replace, rear, sprocket, speed, bike

The mechanism externally has several stars of different sizes, which are fixed with a bushing. After that, everything is connected with a lock nut.

  • The usual version is that the stars are connected to each other by a plastic spacer;
  • Spider cassette. cassettes made in the form of stars, fixed on an aluminum frame;
  • On several spiders. devices that have a high cost and are usually installed on professional and expensive models. The appearance has 2 spiders, which are connected by sets of stars;
  • X-Dome is a monolithic system that connects the drum to the lid on the opposite side;
  • OpenGlide. Most Relevant for Road Bikes.

Why you need to change sprockets on a bike?

The sprocket on a bicycle has one of the main roles that affect ride quality and speed. During the use of a two-wheeled vehicle, a load is exerted on all its component parts.

Replacing the sprockets is essential for proper function and gear shifting. If you do not repair parts immediately after damage, there is such an option that broken parts will accumulate and repair will be quite costly, in some situations it exceeds the cost of the bike itself.

How to remove a rear sprocket on a speed bike

Stages of installing new stars

How does assembly work when replacing a bicycle cassette chainring?

  • Install a new sprocket and fix it.
  • We assemble the cassette completely in the reverse order.
  • Using a puller, mount the drum to the slotted area.
  • The drum must first be leveled.
  • Next, we carry out the process of assembling the bushing. All actions described in the first paragraph are carried out in reverse order.
  • Install the rear wheel and fix it securely.
  • Put on the chain.

It is imperative to check the smooth operation of the transmission. This procedure involves adjusting the rear derailleur.

If everything is carried out according to the proposed instructions, feel free to get on the bike and enjoy the ride.

Disassembly process of transmission cassette

Some theory beforehand. On the rear wheel there can be two variants of parts related to gear shifting.

  • Transmission cassette. This product features modernity and innovative spline mountings that attach to the hub axle.
  • Ratchet. A somewhat outdated model typical of inexpensive speed bikes. The set contains no more than seven gears. As for the mount, it has a thread with external installation parameters.

Let’s focus on the ratchet right away. Changing the rear sprocket on a ratchet bike is not possible. Only change the entire component completely.

Therefore, the topic of the article will be a problem describing a situation when a bicycle cassette star needs to be replaced. As for the set of stars in the transmission, up to 11 pieces are possible, depending on the bike model.

So how do you change the rear sprocket on a speed bike? Consider the algorithm of actions.

  • Take the bicycle wrench for the rear wheel and dismantle it. We sequentially unclench the levers and loosen the fixing of the nut.
  • Now it is the turn for the axle nuts. Using another key, we turn off the mount.
  • The next step involves unscrewing the bearing cone and pulling it out.
  • We take out the axis with all the elements.
  • We take a special tool. a cassette remover. We insert it into the slots.
  • The whip is placed on the largest sprocket. We make rotational movements clockwise.
  • At the same time, using an adjustable wrench, the puller rotates in the opposite direction.

How To Replace A Cog On A Fixed Gear Bicycle

The preliminary stage is over. Such simple actions are possible in ordinary home conditions. We emphasize that if more than one star is worn out, but several, then it is better to replace the entire cassette at once. This option is also desirable when the largest star is damaged.

And one more recommendation. We put all small parts, washers and nuts in a certain place, so that later we do not search all over the room

Required tools

  • A puller suitable for slotted nuts and circlips;
  • Whip. a metal key, consisting of 10-20 links;
  • Adjustable wrench.

How to remove sprockets from the rear wheel of a bicycle?

If this is a ratchet, then everything will be a little easier. If there is special equipment, then even a person who has nothing to do with bicycles can cope with this.

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This requires only 2 tools:

  • special puller;
  • adjustable wrench.

First, of course, you need to remove the wheel. Then the stars are removed in two steps. It is necessary to insert the puller into the ratchet, and then try to turn it counterclockwise with a key.

If the mechanism has never been removed, then it can twist strongly (such is its property) and not give in even under great efforts. Then you need to spray the miraculous WD-40 spray there from the thread side. If you leave it like this for a few hours, then the ratchet can be easily removed. It should also be remembered that the larger the lever, the greater the effort. Therefore, you need to take the largest adjustable wrench. Do a couple of jerks and the ratchet will unscrew easily.

You will need another tool to remove the cassette. It’s called a whip. This is a handle to which a piece of a bicycle chain is attached. If you turn the cassette counterclockwise, it will start to rotate. This is where this whip will come in handy, which will hold her. Some craftsmen simply use a piece of an old chain instead of this tool. Then everything is the same as when removing the ratchet.

How to remove sprockets from a bicycle wheel. sequence of actions

A bicycle cassette with sprockets differs from a ratchet in that individual sprockets can be replaced individually. All that needs to be done is to remove the worn part and replace it with a new one. The space between the individual sprockets on the wheel is filled with spacers and rivets that make dismantling and mounting easier. It is only important not to confuse the sequence. This is especially true for multi-speed mountain models.

It happens that cassettes are equipped with “spiders”. This is a design where several sprockets are rigidly fixed. In this case, if any of the parts is badly worn out, you will have to replace the entire “spider”.

Replacing single sprockets can cause chain switching difficulties is great. This is because the chain is sufficiently worn out in relation to the new sprockets. For this reason, it is advisable to replace the chain and cassette at the same time.

Removing the cassette

To remove the sprocket cassette from the rear axle of the bicycle, you must:

  • Turn the bike over with its wheels up and place it on a flat solid surface, resting on the handlebar and saddle;
  • Unscrew the axle fastening nuts and remove the rear wheel and chain;
  • Install the puller on the slotted nut and put on it an adjustable wrench (or a suitable socket wrench) with an extension;
  • Put a whip on the largest star;
  • Holding the whip with one hand, unscrew the spline nut with the other counterclockwise;
  • Remove the cassette and disassemble it, carefully placing all the stars and intermediate washers in order.

If in the process of subsequent assembly of the cassette the correct sequence of insertion of the spacers is not observed, this can lead to problems when switching speeds while the bike is moving.

How to remove and put a system star

The system is a set of three chainrings. If you often have to ride at speed, then most likely the largest sprocket will wear out. Conversely, with frequent off-road trips, wear will affect the first (smallest) sprocket. By analogy with the second, middle sprocket, when the bike is used at medium speeds in conditions of a dirt road or bad asphalt.

On a modern mountain or road bike, the system is collapsible, so it will not be difficult to dismantle all the stars. Before work, you need to carefully prepare, namely, collect all the necessary tools:

  • connecting rod puller;
  • spanner key;
  • hexagons;
  • new detail;
  • clean cloth and grease.

Removing the system from the bike:
1. Place the frame in a straight position. If you have a stand, you should definitely use it.

Remove the right crankshaft axle fixing bolt with a hexagon.

Unscrew the pedal from the right crank arm. A standard open-end wrench is suitable for this.

Insert the puller into the connecting rod to remove it from the carriage. To begin with, we screw the tool all the way into the thread. It is important that it sits flat on the shaft, otherwise the axle can be damaged when unscrewing the connecting rod. Place the spanner wrench on the puller and screw it in until it stops until the connecting rod is pushed out of the carriage shaft.

The two stars are usually attached to each other on a so-called spider. The big one remains on the connecting rod itself. Unscrew them with the hex bolts.

This is how the system understands.
Replacing and installing looks like the reverse process:

  • Place the desired sprocket on the spider and tighten the fasteners. Change the large part together with the right connecting rod and screw the medium and small sprockets onto it.
  • Next is the installation of the connecting rod on the carriage. Before this, it is advisable to clean and lubricate the carriage shaft.
  • Carefully place the chain on the system and screw in the connecting rod by rotating the puller in the opposite direction.
  • Tighten the fixing nuts and fit the plugs.
  • Screw the pedal onto the connecting rod.
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When replacing one star, it is advisable to clean the old ones. Lightly grease the system components before installing on the carriage.

So just replace the chainring. All the listed tools are required. The connecting rod is a delicate thing, and a hammer and chisel is not the best option for removing it. The same goes for keys. It is difficult to replace them with pliers, besides, the nuts can easily “eat”. Well, without hexagons, it is impossible to disassemble the system into parts.

At the end, check the operation of the transmission. whether everything is in order and whether it is necessary to adjust the speed switch.

Types of bike transmissions

The gear range setting is highly dependent on the driving style. Let’s consider the most typical cases

Change the sprocket on the rear cassette

The set of transmission stars of the rear wheel is several times larger than the front one. The standard kit includes eight components, and in high-speed models (or on a sports bike) there are 9 or 11.

It is worth mentioning right away that a cassette or ratchet can be placed behind. The cassette is a modern version with an internal splined mounting on the hub axle. Ratchets, as an outdated option, can only be found on a budget high-speed bike. The set usually includes 5-7 gears. External fastening, threaded, removable tool differs from cassette.

The fundamental difference from the cassette is its integrity. it is impossible to change the star separately on the ratchet. Here, either all at once, or nothing at all. Therefore, we will consider how to install a new sprocket on the cassette.

Removing and Installing a Freewheel

As with replacing the leading stars, special tools are required here:

  • cassette remover;
  • chain whip-retainer;
  • adjustable wrench or head;
  • optional: wrenches, chain release.

When removing the cassette, you will need to first remove the rear wheel from the bike and then the axle nuts. At the same time, when replacing the sprockets, you can also clean the chain. to remove it, you need a squeeze.

Sequence of work:
1. Remove the rear wheel with a 15 wrench, with an eccentric mount everything is simple. unclench the lever and loosen the fixing nut.

The next step is to unscrew the axle nuts. You will need a 17 key for it. To roll the mount off the rotating axle, we put on an additional nut to fix the axle.

Unscrew the bearing cone and pull out the bearing from the opposite side.

Remove axle with taper and bearing. About the bushing components: if necessary, you can immediately replace them with new ones.

Place the whip on the largest (lowest) star. We will rotate it clockwise.

Use an adjustable wrench or a head to turn the puller counterclockwise.

It is so easy to shoot a cassette at home. Most modern star sets are collapsible, you can install one or two new stars. However, in case of severe wear, when half of the cassette is worn off, it makes no sense to change them separately. Difficulties can also arise if the largest sprocket has been erased, on which all the others are usually attached.

Is it possible to dismantle a cassette without a puller and a whip? In principle, this can be done with a slotted tube and a spanner. The whip can be made by yourself by welding a piece of an old chain to the metal handle of the knife.

When replacing individual stars, especially the middle ones, we disassemble the cassette carefully so as not to lose all the spacer and fixing washers. Everything is easier with a cassette on a spider. it does not need to be disassembled, the star is removed separately from its mount.

Rear transmission assembly:

  • Put and fix a new star, assemble a cassette.
  • Using a puller, install the drum on the spline mount of the sleeve. Before tightening, the drum must be leveled so that the connection does not wear off under load. The whip is not needed here. just rotate the puller clockwise with effort.
  • Assemble the bushing: insert the axle from the cassette side, then the bearing and cone on the left side, fix the axle with nuts.
  • Put on the chain and put on the rear wheel.

Check transmission operation and adjust rear derailleur. Timely replacement of sprockets will save you from unpleasant surprises on trips and will, in general, increase the resource of the bicycle transmission.

Bicycle sprocket care

The rubbing mechanisms of the bicycle must be periodically lubricated and cleaned of dirt. This extends the transmission life and makes driving safer. After several trips on bad roads, forests or, moreover, off-road, the bike is literally overgrown with mud. If the frame and wheels can be washed clean, the contamination of the bike mechanism is simply not visible. Therefore, after such trips, it is not superfluous to inspect the large and take measures to clean the parts, and, if necessary, replace the worn out components.

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You can clean the bike cassette according to this algorithm.

  • Release the rim brake. Alternatively, remove the disc brake caliper;
  • Remove the rear wheel;
  • Examine the cassette carefully. If it is heavily soiled, you will have to remove it from the wheel and clean it. With a little dirt, you can clean the bicycle cassette from dirt without removing it from the wheel;
  • Use special narrow brushes for cleaning, which make it possible to penetrate between the gears and clean out what should not be there. In addition, it is much more convenient than penetrating the gaps with a rag;
  • An old toothbrush is great for cleaning the teeth of the sprockets;
  • Wipe the surfaces with a cloth soaked in kerosene. Then apply lubricant to the teeth and pits;
  • It is advisable to clean the sprocket cassette and chain at the same time. This is the only way to achieve the desired result.

The system is cleaned in the same way. You don’t need to remove the bicycle wheel, but you need to work with the utmost accuracy so as not to accidentally knock off the switch setting.

How do you change the rear sprocket?

pull off the lock washers with a flat screwdriver and hammer, unscrew the bolts with a 14mm wrench or socket, remove the wheel, remove the sprocket, insert a new one and run!

What is a bicycle sprocket?

It is a small cogwheel that the chain runs over the rear wheel, although technically it is any cogwheel designed for a chain, including one turned by a pedal and a crank on a bicycle.

What is a sprocket on a bicycle?

Generally speaking, a sprocket is a gear that can engage a chain. For full size bikes this refers to the part attached to the rear wheel, but for BMX it can also refer to the cogwheel with pedals.

How do you work with bmx sprocket sizes?

Divide the rear sprocket into the front sprocket. Like 25 x 9.25 divided by 9 = 2.77 so 2.77 to 1 is the drive ratio. If you go with a smaller sprocket, like 24 in the front, but still 9 in the back, you drop the gear ratio to 2.66 to 1. So your bike will be slower but lighter on the pedal. If you go with 25 in the front and 10 in the back, you get a 2.5 to 1 ratio.

Do not confuse gear ratio with gears, this is a calculation including wheel and sometimes tire circumference.

You can replace 36 tooth sprocket with 30 teeth?

Yes. You will need to shorten the chain. This will make acceleration easier, but it will reduce the top speed.

When I stop the pedal or pedal backwards on my mens bike with Schwinn tires, the chain falls off because the rear sprocket continues to spin what is wrong with it. How can I fix it?

The clutch mechanism that allows the bike to land is broken. This requires special tools to be replaced, so unless you want a bike mechanic to fix it for you. Tell him you need either a new freewheel or a new free-wheeling body.

How do you fix the rear sprocket on a bmx bike?

There is not much in the rear sprocket that can reasonably be corrected. The most common action is to simply replace it. You need the right freewheel puller to remove it. has a repair and tools page. If your problem is sticking or unattractiveness, you can try to flash and restart it.

Lay the bike on its side, rinse a lot of WD-40 or similar through the gap in the freewheel, see if you get any sponges. Then beat in some liquid oil (motor oil will do) and see if that helps.

Who invented the asterisk?

An asterisk is such a basic engineering component that has been around for so long that the origin is no longer tracked. It was probably invented by several people independently.