Bicycle Crank Shaft: Everything You Need To Know

Crankshafts are an exceptionally significant portion of a bicycle, more especially in a crankset or chainrings. If this part is not functioning suitably then the entire cycle is likely to be off. So, it is important to keep a proper vision on the crankshaft of the bicycle. Do you know, the crankshaft is a part of a chainset or crankset?

Well, no worry dude if you didn’t know before, there is no problem. Because in today’s article I will tell you a lot of unknown information about the crankshaft as well as the crankset, and crank arm. Also, some relatable questions about crankshafts with details about their different types, comparisons, working process, functions, Crankshaft’s health check-up, new crankshafts installation process, old crankshafts removal process, tools required for this work & many more valuable things.

And, I guess you must be very excited hearing all these things. Please hold your excitement a Lil bit longer and read the complete article till the climax.

Bicycle’s Crankset and Crank Arms

At first, I want to talk about the crankset and crank arms, so that you can relate to the crankshaft properly in the further discussion.

Crankset:

The crankset is a part of the bicycle through which you pedal to propel your bicycle forward. In North America, this part of the bicycle is called the “Crankset”, but in the UK it is often known as the “Chainrings”. It can also be said that a crankset is one of those parts of a bicycle that looks very simple but hides all the complexities of this part in the multitude of values, variations, and compatibility issues that exist within it.

• A bike’s crankset consists of special parts, including 2 crank arms, to which the bicycle’s pedals are properly attached, and 1 to 3 chainrings along which the chain moves.
• The chainset is a bicycle drivetrain component that converts the reciprocating motion of the legs into rotational motion by using a chain or belt to drive the rear wheel of the bicycle.
• It is connected to the frame of the bicycle by the bottom bracket through the pedals and also to the rear cassette, freewheel, and sprocket through the chain.

Some Bike’s Crankset Type:

A bicycle chainset comes in three special configurations. They are –

• Single Crankset
• Double Crankset
• Triple Crankset

And, There are 3 types of cranksets found in Mountain Bike. They are-

• Square Taper
• Spline
• One-Piece Splined

Crank Arm:

A crank arm is a part of a bicycle that is simply a crank, more specifically defined as a “bent or vertical handle”. The term crank arm originally appeared as part of the crankshaft. In a word, the crank arm is the offset part of the crankshaft where the connecting rod and piston are attached to the bicycle parts.

• A bicycle crank arm set usually consists of two arms, the non-drive side crank arm, and the drive side crank arm.
• The non-drive side crank arm is the crank arm on the opposite side of the bicycle chain. It is a simple arm that properly connects the bicycle’s pedals and its bottom bracket.
• The drive side crank arm is very complex. It also holds the pedals on one end of the bicycle just like a non-drive crank arm.
• But at the other end, this arm has to be connected to the bottom bracket and it must also be properly connected to the chainrings.

In a word, bike crank arms are a type of part that transfers the pedaling power of your bicycle by perfectly connecting the pedals to the bottom bracket and forward gearing.

Some Bike’s Crank Arm Type:

• One-Piece Crank
• Square Tapers & Splines
• Cottered Crank
• Integrated Crank

But What Is Bicycle Crankshaft Exactly?

Basically, the crankshaft of a bicycle performs a very simple task, but the process can be quite complicated.

• Generally, it translates the linear motion of the bicycle’s pistons into constant rotation.
• It’s doing much the same job as a bicycle crank arm, converting the up and down motion of the rider’s legs into more or less rotation as needed.
• A bicycle’s crankshaft is one of the most special parts of a bicycle’s crankset. It is mostly attached to the crank which has a large end. The main reason is that it supports the rider’s feet when pedaling, so it has to fit around the crank.
• And, Crankshafts often experience many types of fatigue loading conditions. Therefore, the crankshaft material must possess better resistance to wear and tear.

Crankshafts are usually products of carbon steel, fixed steel, or cast-iron materials. So, a crankshaft can be described as the component used to convert the reciprocating motion of the piston into the rotational motion of the shaft or vice versa.

Digest:

1. A crankshaft is a shaft that is driven by a special mechanism of the crank cycle involving a series of cranks and crank pins to which special bicycle part connecting rods are attached.
2. It is a part capable of converting between reciprocating and rotational motion.
3. A reciprocating compressor converts the reciprocating motion into rotational form, while a reciprocating compressor translates it the opposite way meaning that the reciprocating forms rotate.

Bike Crank Shaft: Functions & Parts

Function:

The crankshaft acts as the backbone of the bicycle’s chainset internally. It also rotates the rest of the bicycle through the proper motion to provide power for pedaling forward at the proper speed.

Crankshafts are usually driven continuously and therefore should have very high fatigue strength. Thus it is usually connected to the crank arm so that through the crank arm the proper pedaling is possible.

Crankshaft Parts:

• Crankshaft Pulley
• Crank Arms
• Weight Balancing
• Main Journal

Crankshaft & Crank Arm: How They Work?

The function of bike crank arms is to keep the pedal connected to the bottom bracket and also to transfer the pedaling power by properly aligning it with the forward gearing of the bike.

And, the crankshaft of the bicycle connects the crank arms to the chainring of the bicycle from the middle and continues to rotate while pedaling, due to which the bicycle can move forward comfortably.

Undoubtedly, the crankshaft and crank arm are 2 primary as well as important parts of the crankset of a bicycle. If the crankshaft of the bicycle is not attached, then the crank arms will not be attached properly. And, since the pedals are attached to the crank arms, it will not be possible to ride the bike without them.

Digest:

1. The crankshaft is a very precise part of the bicycle to which the crank arm is attached.
2. And, Through the mechanism of the crankshaft, the bicycle moves forward at a faster speed.
3. In a word, crankshaft and crank arms play a special role in cycling as a complement to each other.

Differences Between Bicycle’s Crank Shaft and Crank Arm

Are Bicycle Crank Shafts Universal?

No, bicycle crankshafts are not universal. You should already know that crankshafts are the most special and important part of the crankset or chainset. As there are different types of cranksets, naturally, there are different types, models, and sizes of crankshafts. Thus Bike Crankshaft is never likely to be universal.

As various types of crankshafts are available in the market depending on the interface of a bicycle, riders may be able to choose different sizes, brands, and models of crankshafts as per their preference.

In short, since a bicycle has different types of crankshafts, it can’t be universal.

Checking Crankshaft Health: Inspection & Solution

Let’s know about Crankshaft health checking and solution in this section where our bike renovation program helps us including me a lot to tell you.

How Do You Check If Your Bicycle’s Crankshaft Is Good Or Bad?

Knowing whether the crankshaft of your bicycle is good or bad is not a very difficult task. A little closer look will tell you how good or bad the health of your crankshaft is. First of all, you need to make sure that you buy the right crankshaft brand. Of course, before buying it is important to check all the features, sizes, and materials.

When the rider can cycle at maximum speed by using any gear in the case of bicycle riding, then it will be understood that the health of the crankshaft is very good.

• At first, when using the crankshaft, make sure that there is not too much dirt on it. Although it is already in very good condition at this time, it still needs special care.
• During bicycle riding, in many cases, dirt from the road gets stuck to different parts of the bicycle. When you clean the bike, be sure to clean the crankshaft thoroughly.
• When you feel that (in the case of cycling), various gears are being blocked for use or the bicycle is getting stuck after a while, then you should understand that the crankshaft is in a very bad condition.

As the crankshaft serves as the base of the bicycle. So, when you feel that your bike can move fast forward without any hindrance or using any kind of speed, then you will understand that the crankshaft is completely correct and in good condition. Furthermore, you can also open the crank arm and visually inspect the condition of the crankshaft.

Also, when you look closely at it, you can get some idea of what it’s like.

• If you see that the crankshaft is not corroded in any direction or there is no rust or mold, then it can be understood that it is in a good condition.
• Again, when you feel your bicycle is obstructed, can’t pick up speed properly, can’t use it, or have trouble pedaling, then you must understand that the crankshaft is in bad condition.

Many times the crankshaft wears out due to excess movement or gets rusted due to various types of rust, then it should be understood that this crankshaft is in a bad position. And, applying the steps I am going to tell you in the very next session, any biker can easily check the health of the crankshaft.

Keep in mind- sometimes it may be necessary to disassemble the entire crankset and then remove the crankshaft to check its health.

Identify Broken Crankshaft

The crankshaft can break for various reasons. Since the crankshaft is one of the most special parts of a bicycle, a lot of pressure is placed on this part. That is why the crankshafts are broken at some point due to corrosion.

Usually, when the crankshaft of the bicycle breaks, in that time various problems occur in the bicycle. Bicycles can make a variety of strange noises. As crankshafts are so closely connected to the bicycle’s crank arm, when it breaks, it is not naturally possible to continue pedaling through the crank arm. And, when you can’t pedal a bicycle, it can never move forward. In short, when the crankshaft breaks, the bicycle becomes almost impossible to ride. So, it needs to identify the bad crankshaft by proper inspection.

1. While riding a bicycle, when you feel that different types of sounds are generated from the bicycle during pedaling, you can understand that the crankshaft may be broken.
2. If a situation arises when you find that while riding the bicycle you suddenly find it difficult to move forward properly, at that time you should check the crankshaft.
3. Finally, if this happens the bike has come to a complete stop, and pedaling through the crank arm is not possible at all. If the bike is not moving forward, then it means that the crankshaft is broken and most of the time, you need to input a new crankshaft.

But, Can A Crankshaft Really Break?

Alright, a bicycle crankshaft can break. Still, in most cases, this part deteriorates before it breaks. Sometimes crankshafts can break due to various welding complications, but this is not a relatively familiar occurrence.

In today’s era, most crankshaft manufacturing companies generate this part of the bicycle with high-quality materials regarding special care and great maintenance. As the crankshaft acts as one of the foundations for bicycle riding, if this part breaks easily then there is a possibility of major problems in riding. Thus everyone constantly pays special attention to this portion. And, special quality control measures are taken when crankshafts are forged and machined.

So, it takes a long time for this part to corrode or fail. And, it can also be said that a bike crankshaft can break but this is a very rare occurrence.

Bike Crankshaft Replacement: The Complete Guide

Average Longevity Of A Crankshaft:

Crankshafts generally do not wear out very quickly, they last for many years as this part of the bicycle is specially made with very high-quality materials. And, generally, a crankshaft lasts indefinitely if you take care of it properly.

Crankshafts help a lot in pedaling as they are closely connected to the crank arm. It acts as a rotational speed to adjust the speed of the bicycle, so it is not used in bearings. Basically, because of that reason, they can provide good service for a long time.

Crankshaft Replacing Time:

When you see that the crankshaft’s health is getting worse, you should replace it. You have already been informed about crankshaft health, when you see all the special symptoms of bad crankshaft health, and what is the right time to replace it.

It usually doesn’t take much time to replace the crankshaft. But if you are a beginner and taking this step for the first time it may take a bit more time. However, replacing the crankshaft of the bicycle was completed in about a Maximum of 1 hour.

If you are having trouble cycling because of the crankshaft, then it must be replaced. Otherwise, various problems may arise in other parts of the bicycle.

Repairing Crankshaft:

Unfortunately, repairing crankshafts can be a very difficult process for the average rider. And, only professionals can do this process properly.

Usually, when a crankshaft is highly damaged or broken, it requires a lot of special tools to repair, which can be very expensive. Moreover, this work has to be done through many special processes that are usually not possible to do at home. That’s why most riders end up replacing the entire crankshaft rather than repairing it.

But Is It Really Hard To Change The Crankshaft At Home?

Whether the crankshaft change at home is hard or easy depends entirely on the experience of the rider and the person doing the change.

• If you are changing the crankshaft for the first time, then you must find it a bit hard.
• On the other perspective, if you are a professional or have experience in changing the crankshaft before, then you will not find this process difficult at all.

Since this bicycle rack is somewhat invisible from the outside, changing it may take some time. But for those who are experienced, that time will be reduced to a large extent.

Therefore, it can be said that this entire matter of changing the crankshaft is hard or easy, it will completely depend on the experience.

And, Can You Replace The Crankshaft Without Removing The Heads?

Replacing crankshafts without removing heads or with heads, depends on your choice. And, a cyclist can choose either method at his convenience, it is not likely to pose any major problem.

If you want to replace the crankshaft without removing the crankshaft head, you can safely do so. And, remember- the crankshaft head helps the bicycle’s crankshaft to work more accurately.

So, YES, you can easily replace the crankshaft without removing the heads.

Removal Procedure Of The Old Crankshaft

Things you’ll need to remove the old crankshaft-

• 15 mm wrench
• Crank puller
• Allen key

In-Detailed Process:

• First, use an Allen key to properly loosen the crankset hex bolts, which allow the left-hand crank arm to be held onto the bicycle crank spindle. And, you must make sure that you loosen the bolts completely as these bolts can be a bit difficult to loosen but you have to keep trying.
• Next, you need to take the bottom bracket tool and fit the small black ring snugly into the adjustment cap of the crank arm.
• Now when the hex bolt is sufficiently loosened, the screw will loosen without much effort and the left crank arm will come out with the chainring.

Then, follow the same procedure to remove the right side crank arm using the Allen key. In this simple way, any biker can remove the entire crankset.

And, after the removal of the crank arm AKA crankset, you can only find the old crankshaft if you look closely. Then turn it lightly using the crankshaft tool.

• After some time, the crankshaft pulley will gradually become lighter and the old crankshaft will come off.

In this way, you can easily remove the old crankshaft of the bicycle. But you must apply only gentle force in every step to avoid any damage.

➢ What Tool Is Used To Remove The Crankshaft Pulley?

You can use a half-inch impact wrench tool to remove the bicycle crankshaft pulley, this can be much more convenient.

More specially, a torque wrench can be used to tighten the pulley more accurately. But before doing these things, you must follow all the guidelines well. Because if you don’t do this properly, you can face various problems in your cycling.

➢ Remove A Crankshaft Without A Special Tool (Pulley)

Apart from a puller or special-made tool, there are several ways to remove a bicycle crankshaft pulley.

• You can use a strap wrench instead of a puller or tool if you want. It can naturally fit around the pulley of your bicycle very effortlessly. And that’s why you can shortly remove the pulley by twisting the wrench with your hand.
• Indifferent from this you can use a pipe wrench. A pipe wrench can easily fit over the pulley of your bicycle’s crankshaft and you can twist it by hand.
• You can also try using a breaker bar to help make turning your wrench easier if you feel it’s too tight.

This way you will be able to easily remove the crankshaft pulley without any special tools.

Installing A New Bicycle Crankshaft

Things you’ll need to install the new crankshaft-

• 15 mm wrench
• Crank puller
• Allen key
• Locking Tool

Details Process:

First, choose a new crankshaft. In the same way that it is opened, it should be installed by slowly turning it using the crankshaft pulley.

• Then the crank pulley must be fitted well so that the crankshaft does not fall off or become loose.
• Using Allen Key, Wrench, and Crankshaft Pulley, the Crank Pulley should be fitted to the new crankshaft in the middle of the bicycle, and the Lock Screws should be properly tightened.

It is very important to check that the crankshaft of your bicycle is installed correctly. So, you must check that the crankshaft is properly locked. Thus find a special type of lock mechanism to lock with the crankshaft pulley of your bicycle, and use a locking tool to lock it in the last step.

• Now, just attach the chainring and crank arm one at a time and your bike will be completely ready for riding.

Check-Out The Proper Installation And Be Sure:

After installing a new crankshaft to the crankset, try a little to see-

• Whether it is possible to pedal the bicycle correctly or not.
• And, is there any kind of noise or any kind of obstacle in increasing the speed, and also if the bicycle is moving forward correctly?

After all these things are checked, when you see that everything is fine, i.e. the bicycle is being pedaled properly, there is no strange sound, gear is being used properly, etc.

And, yes, now you know that you have succeeded, your bicycle’s new crankshaft has been properly installed.

High Voltage Queries About Bike Crank Shaft And Their Answers

1. What Material Is A Crankshaft Made Of?

Most bicycle crankshafts are made of high-quality materials. Some of them are notable – Carbon Steel, Vanadium micro-alloyed steel, Cast iron, and Forged steel. Most of the advanced brands manufacture their bicycle crankshafts using these materials. But some brands use different materials as well.

2. Can You Make A Bicycle Crankshaft At Home?

It can be quite difficult when you want to make bicycle crankshafts at home. Because it requires different types of machines, equipment, chemicals, different temperatures, costly materials, etc. Also, what is needed most is a skill.

To make the right size crankshafts for your bicycle, you must be well-versed and skilled. If you are skilled and have all the necessary instruments at home then you can make a crankshaft home.

But frankly saying, making a crankshaft at home is not an easy task at all. If you want to take all these steps just to make one crankshaft then it may not be worth it for you. So, I would recommend that you use any good brand of crankshafts.

3. Do Crankshaft Bearings Wear Out?

Yes, crankshaft bearings can wear out. At various times, the crankshaft bearings can wear due to excessive heat, pressure, different types of road dirt, oil, various chemicals, or acids adhering to contaminated oil.

Again, many times the crankshaft bearings will wear out immediately, if they grind against each other.

4. Why Is My Crankshaft Pulley Wobbling?

It often happens that the pulleys on the fan-belt of the bicycle crankshaft become distorted or otherwise damaged due to the constant advance when the harmonic balancer bolts on. And, for this reason, the pulley of the crankshaft gets wobbly.

Moreover, the pulley can sometimes wobble due to constant lifting and lowering. It can also be seen that the pulleys are attached by bolts when the bolts are not secured enough for various reasons, it starts to wobble.

5. What Happens If The Crankshaft Pulley Breaks?

The crankshaft pulley is a special part of crankshafts. If this part breaks for some reason, the entire crankshaft may be damaged, even the entire cycle can stop.

And, a biker should never cycle with a broken pulley, as this can lead to problems with other parts of your entire bicycle.

6. How Much Is The Price Of A Crankshaft?

The crankshaft purchasing cost mainly depends on the brand and quality. The price of this part of the bike is not very high. You can find a good quality crankshaft for your bicycle for under $100. Moreover, there are other crankshafts whose prices are slightly higher.

7. Does The Crankshaft Come With The Crankset?

Yes, most of the crankshaft comes with a bicycle crankset.

Crankshafts do not get damaged very easily due to which it is possible to use the one that comes with the bicycle crankset for a long time. But many times, if the crankshaft is damaged, you have to buy it separately.

Last Sayings Over Bicycle Crankshaft Ultimate Guide

I Hope today’s article gave you a unique idea about a new topic such as a proper understanding of the importance of a crankshaft, crank arm, and crankset for a bicycle. And, more keen information including the old Crankshaft removed, new crankshafts attached and significant differences between crankshafts & crank arm with various related question answers.

And, I really believe that all these new types of information will be very helpful in your actual cycling life, especially to look after your entire crankset and its parts like crank arms, crankshaft, and used bearings.