Leading Star System (bike)

The most common types of systems can be divided into groups.

Usually, the stars are attached to the connecting rods with three to six bolts (usually four or five). ^[2] The element of the system to which the stars are attached is often referred to as a “spider,” due to its shape resembling a “paw” spread out in all directions. Accordingly, with the number of mounting holes, systems are referred to as “three-armed”, “four-armed” and so on.

Ability to replace stars

Removable stars allow you to replace them in case of wear or damage. It also allows you to set stars with different numbers of teeth for different conditions, thus changing the gear ratio. In low-cost bike systems, stars are often fixed.

Specific Bicycle Systems

In tandem bicycles, systems usually have extra stars for transmitting torque from the pedals of the second rider. The disc brake integrated in the system is used on bicycles with a hub without free wheeling (for example, on bicycles for a bike trial ). And sometimes the freewheel mechanism is also located in the system of leading stars.

Specific systems include those designed for bicycles with a non-standard transmission (for example, a belt or shaft drive ).

Recently, systems with oval stars have become popular. Today, oval stars are mass-produced by all major manufacturers: E13, Race Face, Blackspire, AbsoluteBlack, Kore, OneUp Components. Available in all the most common standards, in a single version and for switching. The advantage of such stars is the increased efficiency of pedaling. In the process of pedaling, the force is applied unevenly, and oval stars work due to this, more correctly distributing the load. It feels like such a star is more "round" than ordinary. With these stars it’s easier to climb uphill, accelerate and pedal in soft ground. The disadvantages include increased wear of the chain and the star itself (relative to round stars of the same material), for oval stars under switching - higher demands on the setting of the front derailleur. Also, with a high cadence, when trying to switch to a smaller star, a situation is possible when the chain does not have time to completely release the big star, as a result of which the chain can be “chewed” between the frame feather and the big star, which can lead to breakdown of the star and chain. To prevent this situation, it is recommended to reduce the difference in the number of teeth on the large and small stars compared to a system with ordinary round stars.

Landing diameters of stars

Bolt circle diameter (BCD) is the diameter of the circle on which the bolts that secure the star are located ( jargon bonki ). ^[3]

Carriage Shaft Mounting Standards

There are different standards for mounting the system to the carriage shaft:

• wedge joint, previously widely used on most bicycles
• square connection of several varieties (JIS, ISO , JISLP)
• spline connection , also found in different versions ( Shimano Octalink, ISIS, etc.)

In some cases, the carriage shaft and one of the connecting rods are made integral. There are also systems in which both connecting rods form a single part with the shaft (found, for example, in BMX ).

Rod Length

The length of the connecting rod should be proportional to the length of the legs of the cyclist. ^{[6] [7]} In order for two cyclists of different stature, at the top point of the amplitude, to raise the leg at the same angle, they must have connecting rods of different lengths. The most popular on the market were connecting rods from 160 to 180 mm. Although the optimal ratio of the athlete’s anthropometry and the length of the connecting rod is selected empirically, indicative recommendations can be obtained from the reference books ^[7] and calculators ^{[8] [9]} , the data of which are indicated in the table:

Chainline (distance to chain)

Bicycle frames are created for a specific chainline (English - chain line) . Chainline is the distance between the diametrical plane of the bicycle and the center of the set of stars of the system (that is, to the only star of the system with one star, or the middle of the distance between the stars of the "double", or the middle star of the "tee"). To comply with the chainline, it is necessary to select a carriage with a suitable shaft length for the system. Typically, recommendations for choosing a carriage are provided by the system manufacturer.

Pedal Mounting

Almost all pedals of modern bicycles are attached to the connecting rods by means of a threaded connection, with the right pedal having the right thread and the left pedal having the left one (to prevent spontaneous unscrewing). The axis of the pedal with the left-hand thread is necessarily marked in the form of letters L or L at the end. The most common pedal threads are :

• 9/16 "x 20 tpi - inch thread with a pitch of 20 turns per inch, used in most modern bicycles.
• 14 mm x 1.25 mm is the metric standard used in the USSR and some European countries.

As for their interchangeability: since the dimensions of the inch thread translated into the metric system are slightly larger and amount to 14.288 mm x 1.27 mm, the axes of the pedals with metric thread can generally be screwed into the connecting rods with the inch (but not vice versa). But, since we are dealing with a heavily loaded unit, this seeming compatibility in practice will lead to an ever-increasing backlash and subsequent breakage and breakdown of the thread.

On bicycles for MTBs , a protective ring made of aluminum or plastic is often installed on the systems, called rockring, bashring or bashguard (from the English bashguard), which protects the stars from damage during impacts. Often this ring is installed instead of the largest star of the system.

Also, additional devices can be designed to prevent the chain from flying off or to prevent clothing from falling between the chain and the stars.

Special systems with load cells can be used to measure the power applied during pedaling.

• Bicycle transmission
• Bicycle gearshift
• Bicycle chain
• Rear star system (bike)