If you ride a bike often or just like to know how it works, you've probably wondered at some point what a bicycle crankset is. Although it's rarely given much attention, it's a key component of pedaling and directly affects how power is transmitted from your legs to the wheels.
Why is the connecting rod important?
The crank is the link between the pedals and the bike's axle. Its size and material can influence how you pedal, how comfortable you are, and even help prevent discomfort or injury. Choosing the right crank can make cycling more efficient and enjoyable, whether you're racing or just going for a ride.
In this Shad Bikes article, we'll look at what a bicycle crankset is, how it works, and what you should consider when choosing one and keeping it in good condition.
Definition and function of the connecting rod
To fully understand what a bicycle crank is, it's enough to know that it's the part that connects the pedal to the bottom bracket. Its function is simple but crucial: to transmit the force we apply when pedaling so that the bike moves forward. Without the crank, the pedals wouldn't turn and the bike wouldn't move.
How does the connecting rod work?
Every time we press a pedal, the crank rotates around the bottom bracket axle and moves the chain across the chainrings. This causes the rear wheel to spin and the bike to move. The length of the crank influences the way you pedal:
-
If it is longer, it generates more force with each pedal stroke, but it also requires more effort.
-
If it is shorter, it allows you to pedal faster with less effort, something useful on climbs or long distances.
Connecting rod parts and their relationship to other components
To fully understand what a bicycle crankset is, you need to know how it connects to other parts for efficient pedaling. Although it looks like a simple bar, its function depends on several elements that work together to move the bike.
Main parts of the connecting rod
-
Crank arm: This is the elongated part that connects the pedal to the bottom bracket axle. Its size influences comfort and pedaling power.
-
Pedal anchor: This is the area where the pedal screws in. The threads must be compatible with the type of pedal you use.
-
Bottom bracket connection: This is the other end of the crank arm, which attaches to the bottom bracket and allows it to rotate. There are different types of connections, such as square drive, integrated axle, or two-piece systems.
How the crank relates to other parts of the bike
The connecting rod does not work alone, but works with other key components:
-
Pedals: they are screwed to the crank and are the cyclist's support point.
-
Bottom bracket: Allows the crank to rotate smoothly. If it's in poor condition, it can cause creaking or resistance when pedaling.
-
Chainrings and chain: The crankset moves the chainrings, which transmit power to the chain and turn the rear wheel.
Types of cranks according to the use of the bicycle
Now that we know what a bicycle crank is and what it's used for, it's time to understand that not all cranks are the same. Depending on the type of bike and its intended use, cranks vary in size, material, and design to better adapt to each situation.
Cranksets for road bikes
Road bikes are designed to go fast and pedal efficiently, so their cranks are usually:
-
Light and rigid, usually made of aluminum or carbon.
-
Standard length (between 165 mm and 175 mm), ideal for pedaling at high cadence.
-
Designed for large chainrings, which helps maintain speed on long, flat stretches.
Mountain bike cranks
Mountain bikes require more durable cranks to withstand impacts and rough terrain. Their key features are:
-
Robust materials, such as reinforced aluminum or, in some cases, steel.
-
Variable lengths, adapted to the technique and type of route. Shorter cranks are often used on technical trails to improve control.
-
Compatibility with single or double chainring systems, making it easier to shift gears on climbs and descents.
Cranks for urban and touring bicycles
City and touring bikes aim for comfort and durability, so their cranks are simpler and stronger:
-
Durable materials, such as aluminum or steel, to withstand daily use.
-
Standard length, adapted to a more comfortable pedaling position.
-
Simple transmission systems, requiring little maintenance.
Materials and technology in the connecting rods
Now that we know what a bicycle crank is and the different types depending on its use, let's look at the materials they're made of and the technology used to improve their performance. The crank material influences its weight, strength, and durability, so choosing the right one can make all the difference when pedaling.
Most common materials in connecting rods
Cranks are made from different materials, depending on the type of bicycle and its intended use:
-
Aluminum: The most commonly used because it's lightweight, durable, and affordable. It's found on most bikes, from road to mountain.
-
Carbon: Lighter and stiffer than aluminum, but also more expensive. It absorbs vibrations better and is used primarily in high-performance bikes.
-
Steel: Heavier but very strong, ideal for urban or touring bikes, where durability is key.
-
Titanium: Uncommon due to its high price, but it combines lightness, strength and a certain flexibility, which improves comfort.
Technology in the cranks
In recent years, connecting rods have evolved with advances that improve their performance and efficiency:
-
Hollow connecting rods: Some brands make them hollow inside to reduce weight without losing strength.
-
Integrated bottom brackets: Improve stability and reduce wear by eliminating unnecessary moving parts.
-
Power meters: Some cranks have sensors that measure the force applied with each pedal stroke, which is very useful for advanced training.
Connecting rod maintenance and common problems
To keep your bike running smoothly and trouble-free, it's important to take care of the crankset and check its condition from time to time. As it's a key component of pedaling, if it's worn or improperly adjusted, it can cause the bike to perform poorly or even cause discomfort when riding.
How to know if the connecting rod is in bad condition
If you notice any of these symptoms, your crank may need adjustment or replacement:
-
Creaking or noises when pedaling: This could mean that the crank is loose or that the bottom bracket needs lubrication.
-
Strange movement in the pedals: If the crank moves too much or has play, it may be improperly adjusted or worn.
-
The pedal frequently loosens: the crank thread may be damaged and need repair or replacement.
-
Visible cracks or deformations: If you see that the connecting rod is bent or has cracks, it must be replaced as soon as possible.
How to care for your connecting rod to make it last longer
If you follow these tips, your crank will stay in good condition for longer:
-
Check the tightness of the cranks: make sure the bolts or clamping system are tight to avoid looseness.
-
Grease the joints: Applying a little grease to the area where the crank meets the bottom bracket axle helps reduce noise and wear.
-
Clean the connecting rod from time to time: mud and dirt can accumulate and affect its performance.
-
Replace the connecting rod if it is damaged: If it has cracks or the threads are worn, it is best to replace it to avoid problems.
When should the connecting rod be changed?
Although a well-maintained connecting rod can last for many years, there are situations in which there is no other option but to change it:
-
If it has cracks or is bent.
-
If the pedal thread is worn and the pedal does not screw in properly.
-
If you notice looseness when pedaling or lack of stability.
-
If it is very worn in the area where it joins the bottom bracket axle.
How to choose the right connecting rod
Knowing what a bicycle crankset is not only helps you understand its function, but also helps you choose the best one for your bike type and pedaling style. The crankset influences comfort, efficiency, and even injury prevention, so it's a good idea to keep a few details in mind before changing it.
What to look for when choosing a connecting rod
If you need to change your bike's crank, keep these things in mind:
-
Length: Typically between 165 mm and 175 mm, although there are more options. Longer cranks help generate more power, but require more effort. Shorter cranks allow you to pedal faster and with less impact on your knees.
-
Material: Aluminum frames are the most common because they're light and strong. Carbon frames are even lighter and stiffer, but also more expensive. For urban or touring bikes, steel frames tend to last longer.
-
Bottom bracket compatibility: Not all cranks fit all bikes. There are different mounting systems (square, integrated, two-piece, etc.), so make sure the crank is compatible with your bottom bracket.
-
Type of bike and use: Road bikes require lightweight cranks, mountain bikes prioritize durability, and urban bikes prioritize durability and low maintenance.
How the crank influences pedaling
The crank directly affects the way you pedal:
-
If it's too long or short for you, it can cause you to strain your posture and end up hurting your knee or hip.
-
If it's too heavy, it can make you lose efficiency when pedaling.
-
If it is not compatible with the transmission system, it can cause mechanical problems and premature wear.
Conclusion
Now that you know what a bicycle crank is and why it's so important, it's clear that it's not just another component, but a key part of pedaling. Its design, material, and maintenance can make a difference in the comfort, efficiency, and durability of your bike.
Choosing the right crankset for your bike type and pedaling style is essential to avoid discomfort and get the most out of it. Plus, with proper maintenance, you can prevent breakdowns and ensure your bike performs well for longer.
At Shad Bikes, we know that every cyclist has different needs, which is why we offer practical and durable equipment so you can enjoy your bike comfortably and safely. If you're looking for quality bike accessories for your daily rides or your two-wheeled adventures, check out our range of products.
