How to choose cranks for a bike

Manufacturing materials

The connecting rods, like the frames themselves, can be made of various materials. Currently actively used:

  • steel;
  • aluminum;
  • carbon;
  • titanium.
choose, cranks, bike

Steel products are lightweight and therefore make the bike heavier. To facilitate the overall design of the bike, manufacturers choose to use hollow parts or provide an external groove. Die-cast one-piece models are used for road bikes, mountain bikes need a lighter design of all systems and therefore are equipped with tubular parts. As with all bike parts, steel cranks are found on budget bikes and in the BMX discipline.

The aluminum connecting rods are significantly lighter. Thanks to them, the bike itself becomes lighter. They are made by cold or hot forging, which greatly increases the strength of the parts and minimizes the likelihood of sudden breakage. They can also be made hollow to further reduce weight. Aluminum cranks are the most common in the cycling industry, as they traditionally have the best balance of price, quality and weight.

Titanium and carbon cranks are used to equip expensive professional bikes. Their cost is much higher than their aluminum counterparts and it is justified only when trying to save the bike from every extra gram of weight.

Manufacturers often opt for combined systems, when the carbon part is reinforced with aluminum or titanium inserts. In budget models, steel connecting rods are reinforced with aluminum.

Carriage attachment systems

There are many options for attaching the cranks to the carriage axis:

  • wedge-shaped pin. a method that involves connecting all parts into a single unit using a fastening wedge. Used extensively in the last century. Currently, this design is used exclusively in children’s steel horses;
  • square end of the shaft. provides for the fastening of both levers on the square profile of the shaft using a nut or screw. The connecting rods have a square bore, the shaft expands towards the frame and has a pyramidal shape. The carriage assembly is equipped with a plastic boot, protecting the joints of parts from contamination. This type of fastening is also considered obsolete and is usually installed on budget models;
  • hexagonal end. the right and left cranks are attached to the shaft and fixed on it at a slight angle. In Shimano-designed designs, the bolts are tightened with an 8-point Allen key;
  • spline connection. provides for the presence of a through hole on the shaft with an increased diameter. Gross ends have a rounded shape. The connecting rods are attached to the bicycle with a large hollow bolt, most often under a hexagon of 10. The outer connection is covered with a plastic boot;
  • bike mount with integrated axle. consists in connecting the carriage axle and one of the connecting rods into a single piece. The other can be attached in any of the above ways. Most manufacturers of road bikes, as well as models for extreme riding, opt for this fastening system.

Bicycle cranks and what they are

Cranks are an integral part of the bike and provide continuous movement of the rear wheel. Mounts directly to the bike and connects directly to a single unit with a frame, sprocket and carriage. Almost every cyclist sooner or later faced the problem of replacing this part. The article will help you understand what bicycle cranks are and what they are.

Modifications

Currently, their 3 modifications are most widely used, each of which has both advantages and disadvantages:

  • one-piece. is a single part installed in the carriage assembly and connecting the connecting rods and the carriage shaft. It is considered a classic, used in budget models and models for children. The design is distinguished by significant weight, but this is what provides it with a number of advantages: strength, reliability, rigidity, ease of maintenance;
  • two-piece. used in many modern bikes. The design consists of a hub axle and one or both levers pressed into it. The two-piece assembly of the well-known Shimano brand uses cranks equipped with special pressure devices. This type of construction is supplied with external bearings and does not need pullers when dismantling;
  • three-piece. represents the node where the right and left connecting rods, as well as the carriage shaft, are bolted together. The advantage of this system is the ability, if necessary, to disassemble and clean the structure. Currently it is installed on every second bicycle produced. Especially often it is equipped with mountain modifications;
  • the latest rotor system has not yet become widespread among bicycle manufacturers due to its high cost. Its main advantages are the reduction of the load on the rider’s tendons and knee joints due to the displacement of the cranks by several degrees, as well as the associated increase in power by 15-16%.

The universal shape allows the installation of cranks of any size. Typically, their standard lengths are between 145 mm and 185 mm. It is measured from the center point of the carriage axis directly to the center of the pedal axis. The 5mm pitch allows the crankset to be optimally matched to individual needs. When choosing this component of the bike, it is recommended to focus on the cyclist’s height, the length of his legs, as well as the type of frame design. Longer cranks with a short frame make it uncomfortable to ride. It takes more effort to spin the short levers, but these cranks are the most adaptable to maintain a constant speed. So, a track bike is equipped with shortened levers by default, a mountain bike with longer ones. A bicycle for children and teenagers should not have a crank length exceeding 170 mm, as their excessive size can lead to inconvenience when entering a turn.

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Operating principle

Connecting rods (cranks) are special devices that are installed directly on the carriage shaft and to which the pedals are attached. These kind of levers transfer the energy generated as a result of torsion of the pedals directly to the carriage shaft and further, due to the chain of stars (stars) to the rear hub. They are highly durable and the need for their selection and replacement arises only as a result of infrequent breakdowns or when replacing sprockets. And also in cases where the bike is equipped with their non-separable modification, which is typical for most inexpensive models.

Each manufacturer strives to make their bike unique. In addition to imparting unique design features, great attention is paid to details, including the crank systems. including the right and left connecting rods, as well as the carriage shaft and sprockets. The drive sprocket can be integrated with the right arm or have separate mountings. A bicycle equipped with them is more practical, since it allows you to change the stars as they wear out, without having to replace the entire assembly in the kit. The cranks are connected to each other by the carriage shaft. When choosing a bike, you should take into account which system is installed on the bike.

When choosing connecting rods for a bicycle, one should take into account their design features, material of manufacture, methods of joining parts, as well as the individual characteristics of the cyclist. This will help you not be disappointed in the purchase and make cycling comfortable and safe.

Modifications

Currently, their 3 modifications are most widely used, each of which has both advantages and disadvantages:

  • one-piece. is a single part installed in the carriage assembly and connecting the connecting rods and the carriage shaft. It is considered a classic, used in budget models and models for children. The design is distinguished by significant weight, but this is what provides it with a number of advantages: strength, reliability, rigidity, ease of maintenance;
  • two-piece. used in many modern bikes. The design consists of a hub axle and one or both levers pressed into it. The two-piece assembly of the famous Shimano brand uses cranks equipped with special pressure devices. This type of construction is supplied with external bearings and does not need pullers when dismantling;
  • three-piece. represents the node where the right and left connecting rods, as well as the carriage shaft, are bolted together. The advantage of this system is the ability, if necessary, to disassemble and clean the structure. Currently it is installed on every second bicycle produced. Especially often it is equipped with mountain modifications;
  • the latest rotor system has not yet become widespread among bicycle manufacturers due to its high cost. Its main advantages are the reduction of the load on the rider’s tendons and knee joints due to the displacement of the cranks by several degrees, as well as the associated increase in power by 15-16%.

The universal shape allows the installation of cranks of any size. Typically, their standard lengths are between 145 mm and 185 mm. It is measured from the center point of the carriage axis directly to the center of the pedal axis. The 5mm pitch allows the crankset to be optimally matched to individual needs. When choosing this component of the bike, it is recommended to focus on the cyclist’s height, the length of his legs, as well as the type of frame design. Longer cranks with a short frame make it uncomfortable to ride. It takes more effort to spin the short levers, but these cranks are the most adaptable to maintain a constant speed. So, a track bike is equipped with shortened levers by default, a mountain bike with longer ones. A bicycle for children and teenagers should not have a crank length exceeding 170 mm, as their excessive size can lead to inconvenience when entering a turn.

Manufacturing materials

The connecting rods, like the frames themselves, can be made of various materials. Currently actively used:

  • steel;
  • aluminum;
  • carbon;
  • titanium.

Steel products are lightweight and therefore make the bike heavier. To facilitate the overall design of the bike, manufacturers choose to use hollow parts or provide an external groove. Die-cast one-piece models are used for road bikes, mountain bikes need a lighter design of all systems and therefore are equipped with tubular parts. As with all bike parts, steel cranks are found on budget bikes and in the BMX discipline.

The aluminum connecting rods are significantly lighter. Thanks to them, the bike itself becomes lighter. They are made by cold or hot forging, which greatly increases the strength of the parts and minimizes the likelihood of sudden breakage. They can also be made hollow to further reduce weight. Aluminum cranks are the most common in the cycling industry, as they traditionally have the best balance of price, quality and weight.

Titanium and carbon cranks are used to equip expensive professional bikes. Their cost is much higher than their aluminum counterparts and it is justified only when trying to save the bike from every extra gram of weight.

Manufacturers often opt for combined systems, when the carbon part is reinforced with aluminum or titanium inserts. In budget models, steel connecting rods are reinforced with aluminum.

Operating principle

Connecting rods (cranks) are special devices that are installed directly on the carriage shaft and to which the pedals are attached. These kind of levers transfer the energy generated as a result of torsion of the pedals directly to the carriage shaft and further, due to the chain of stars (stars) to the rear hub. They are highly durable and the need for their selection and replacement arises only as a result of infrequent breakdowns or when replacing sprockets. And also in cases where the bike is equipped with their non-separable modification, which is typical for most inexpensive models.

READ  What wheel size should you choose for an adult bike?

Each manufacturer strives to make their bike unique. In addition to imparting unique design features, great attention is paid to details, including the crank systems. including the right and left connecting rods, as well as the carriage shaft and sprockets. The drive sprocket can be integrated with the right arm or have separate mountings. A bicycle equipped with them is more practical, since it allows you to change the stars as they wear out, without having to replace the entire assembly in the kit. The cranks are connected to each other by the carriage shaft. When choosing a bike, you should take into account which system is installed on the bike.

Crank Type Identification

Carriage attachment systems

There are many options for attaching the cranks to the carriage axis:

  • wedge-shaped pin. a method that involves connecting all parts into a single unit using a fastening wedge. Used extensively in the last century. Currently, this design is used exclusively in children’s steel horses;
  • square end of the shaft. provides for the fastening of both levers on the square profile of the shaft using a nut or screw. The connecting rods have a square bore, the shaft expands towards the frame and has a pyramidal shape. The carriage assembly is equipped with a plastic boot, protecting the joints of parts from contamination. This type of fastening is also considered obsolete and is usually installed on budget models;
  • hexagonal end. the right and left cranks are attached to the shaft and fixed on it at a slight angle. In Shimano-designed designs, the bolts are tightened with an 8-point Allen key;
  • spline connection. provides for the presence of a through hole on the shaft with an increased diameter. Gross ends have a rounded shape. The connecting rods are attached to the bicycle with a large hollow bolt, most often under a hexagon of 10. The outer connection is covered with a plastic boot;
  • bike mount with integrated axle. consists in connecting the carriage axle and one of the connecting rods into a single piece. The other can be attached in any of the above ways. Most manufacturers of road bikes, as well as models for extreme riding, opt for this fastening system.

Bicycle cranks and what they are

Cranks are an integral part of the bike and provide continuous movement of the rear wheel. Mounts directly to the bike and connects directly to a single unit with a frame, sprocket and carriage. Almost every cyclist sooner or later faced the problem of replacing this part. The article will help you understand what bicycle cranks are and what they are.

When choosing connecting rods for a bicycle, one should take into account their design features, material of manufacture, methods of joining parts, as well as the individual characteristics of the cyclist. This will help you not be disappointed in the purchase and make cycling comfortable and safe.

HOW TO CHOOSE THE LENGTH OF THE CONNECTING RODS?

Cyclists often underestimate the importance of correct crank lengths, neglecting an element that can be critical to human-bike performance.

If, for example, you are an inexperienced cyclist and are not able to understand the advantages and disadvantages of connecting rods of different lengths, then this is by no means a reason to think that the choice of this component can be overlooked.

How To Find What Size Your Bikes Cranks Are. Bicycle Crankset Size

Fitting experts at IDmatch BikeLab explain what the choice of crank length should depend on and how it affects pedaling efficiency.

choose, cranks, bike

First of all, it should be remembered that anthropometric, physiological and situational factors influence the choice of the length of the connecting rods.

Anthropometric factors are quite easy to understand, because it is the length of the segments of the lower extremities of your body: hips, legs and feet. The latter, often underestimated by the way, are the element that proportionally affects the longest connecting rods.

For example, if two people have the same leg length but different foot lengths, you can use different crank lengths. This is mainly due to the fact that the leg, by changing the bend, can lengthen or reduce the system of the lower limbs by several millimeters and, therefore, can change the dynamics of all elements, especially the knee joint.

Physiological factors mainly relate to the individual elasticity of the muscles and joints of the rider and, therefore, the ability to obtain the best performance at various pedaling rhythms. Understandably, smaller cranks contribute to higher cadence compared to longer cranks.

Situational factors refer to the type of performance required. For example, it is clear that in a cycling race on a track where there are many 180 ° turns, the bike will need to be decelerated and re-accelerated frequently. In these cases, smaller cranks will make it easier to gain speed.

In some competitions, such as fixed-gear bicycles, where the pedals rotate even in corners, shorter cranks must be used. Short cranks in this case allow for cornering, avoiding touching the ground with the pedals.

Taking into account all these considerations, you can proceed to the choice of the length of the connecting rods, based on anthropometric factors.

This selection should mainly take into account the arc of the circle marked by the center of the knee during a full pedal revolution.

The longer we hold this arch in an upright position (relative to the vertical axis of the pedal) while turning the crank 90 °, the more effective the pedal will be pressed.

It doesn’t just depend on the length of the connecting rods. The size and orientation of the arch of the circle marked by the knee is also highly dependent on the position of the saddle in terms of its height and offset.

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Always remember that pedaling has a circular motion that has a center of rotation as the only point of reference. Therefore, shorter or longer connecting rods do not affect the distance between the seat and the center of rotation.

Changing the distance between the saddle and the center of rotation in accordance with the change in the length of the connecting rods can significantly change the size and orientation of the arch of the circle marked by the knee.

You can choose the length of the cranks that suits you according to the methodology and on the equipment of the IDmatch bicycle laboratory by going through the complex bikefit at PROvelo.

How to choose cranks for a bike

Open

Such carriages are a carriage shaft with a set of bearings pressed by cups and screwed into the carriage tube of the bicycle frame.

Their main drawback, however paradoxical it may sound, is their openness. Dirt, moisture, and other road debris can quickly clog the carriage, so it must be handled and cleaned frequently. However, it can serve faithfully for a neat owner for many years, it is enough only once to choose the right carriage for a bicycle.

Shimano OctaLink

This is the Shimano standard, which is a closed bottom bracket with spline and round shaft. It is not difficult to guess that only systems made by Shimano will fit such carriages. Thanks to the splined connection, it has become possible to produce a carriage with a large hollow shaft. This results in a reduction in weight and an increase in shaft stiffness when compared to a square connection.

Closed

Or, as they are also called, cartridge. They are a non-separable, one-piece housing with bearings and a carriage shaft, which is screwed into the carriage tube of the bicycle frame.

This design avoids the ingress of moisture, dirt or sand and completely eliminates misalignment of the bearings. But closed carriages have one significant drawback. the carriage will order a long life immediately after water or dirt gets inside the cartridge. The reason is the inability to disassemble the cartridge (you have not forgotten that this is a one-piece part?).

To choose a bottom bracket for a bicycle, you need to know its size.

With the length of the axis, things are a little more complicated. If there are only two standard diameters, then the axle length standards are several times larger. The mountain bike provides the following standards. 110 mm, 113 mm, 118.5 mm, 122.5 mm and 128 mm. Take the Truvativ Overdrive DH, for example, which is exclusively available in 128mm lengths.

From all this, we can conclude. choose the length of the carriage axis, focusing on the length of the carriage tube of your bike frame, the type of system and the number of stars on it.

And the last thing left to figure out before choosing a bottom bracket and a system for a bicycle is what types of connection between the bottom bracket and the connecting rods are.

On Soviet bicycles and Russian-made bicycles, the connection of the carriage shaft with the connecting rods using a blade (key) is used. But let’s say right away. this design is unreliable and tends to loosen up if the key was not screwed in properly before the first trip. But, despite this, she also has an advantage: it lies in the rather easy removal of the connecting rods without special pullers.

Imported bicycles are mostly squared. The ends of the shaft in such carriages are in the form of a cone with a square section, on which the connecting rods sit. Such a connection is quite rigid and does not loosen over time, since the load is not on the key, but directly on the shaft.

Advanced mountain and road bikes have gone further. They use the so-called spline connection today. There are 2 standards:

ISIS Drive

This is a spline standard that is supported by such well-known manufacturers as Race Face, FSA, Truvativ, Chris King, Bontrager, Stronglight. This standard is not inferior in reliability to the OctaLink standard, but due to the different number of slots, they are completely incompatible.

How to choose the right bottom bracket and crankset for your bike

Eh, I’ll pump it!. and the cyclist flew along the track or down the hill. Wind, speed, adrenaline Do you crave these sensations? Then be smart about choosing a bicycle carriage, because it is she who is directly responsible for the torque transmitted from it to the wheels. But before that, we will teach you how to choose the right bottom bracket and connecting rods for your bike.

An experienced cyclist knows what a bottom bracket and cranks are and what they are for. We explain to beginners: the bottom bracket is a bearing unit that provides rotation relative to the bicycle frame of cranks with pedals and leading sprockets. The point of life of the bottom bracket is to transmit torque with minimal losses from the pedals to the wheel.

It is located at the bottom of the frame behind the front wheel. This arrangement leads to the fact that the carriage assembly is constantly thrown by dirt and water, therefore, reliable protection of the carriage bearings is a guarantee of its long and happy life.

To choose a carriage for a bicycle, first you need to figure out what they are. All carriages can be divided into two groups:

Let’s summarize. What connecting rods and carriage to choose for a bicycle?

It is rather difficult to advise something specific in this case. Bogies and squared systems are still supported and are available in both cheap and very expensive versions.

choose, cranks, bike

Important note. ISIS is more suitable for aggressive use than other types, and the square wins in terms of pricing.