How Do Bike Gears Work

Bike gears are the most important system that comes to mind when talking about the transmission of a bicycle. Although the main component of the transmission is the chain of the bicycle, an element that transmits the motion from the pedal to the wheel, the gears define, in a sense, the racing power of the bike.

The bike gears are a concentration of genius and mechanical perfection. This component can be considered the heart of a bike and in fact, the gearbox allows you to adjust the speed to diminish the effort and increase the cycling performances.

Unless you are a mechanic, understanding the functioning of this system can be tricky. So, let’s see how do bike gears work and, above all, understand how to use them effectively.

Anatomy Of The Bike Gearbox

In technical terms, the bike gearbox is a shifting system that consists of:

  • Shifting levers
  • Gasket
  • Front chainrings
  • Rear sprockets
  • Chain
  • Front derailleur
  • Rear derailleur
  • Cables and sheaths

This set of components works in symbiosis to allow the cyclist to choose the gear ratio to be used during cycling and to adjust the transmission based on circumstances, such as riding uphill or downhill, on flat surfaces or on serpentines.

To change gear, the shifting levers transmit the commands to the derailleurs through a cable system, while the derailleurs are responsible for moving the chain from one chainring or sprocket to the other.​

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How Do Bike Gears Work

Each time you change the position of the chain, you select a gear ratio. This ratio allows you to cover a determined distance with a single pedal stroke and indicates a metric development value that is directly proportional to the number of teeth present on the selected chainring.

The metric development is also influenced by the number of teeth present on the rear sprocket and by the circumference of the wheel.

The metric development is important because it allows you to understand what distance you can cover on a single stroke, therefore decide how to change the gears to achieve the best cycling results. Moreover, the metric development will also give you an insight on how to expand the gear choices, especially if you are dealing with rapidly changing paths that require the use of different settings.

There is a simple formula to calculate the metric development. All you’ll have to do is multiply the number of teeth of the chainring you want to use with the dimension in millimeters of the diameter of your wheels, then divide the amount by the number of teeth of the rear sprocket. The result is the distance you can cover on a single pedal stroke, expressed in meters.

If you want to draw a metric development chart, you can simply make this calculation for all the possible combinations of gears and you will know in each moment what is the most effective combination to use.

How To Pedal At The Right Pace

A question inexperienced cyclists often ask is if there is a “right” cycling pace. And the answer is yes! To pedal efficiently, you must not overload your muscles and joints. The ideal pedaling frequency is around 80 cycles per minute and the value can slightly change depending on your position on the saddle and experience.

Nevertheless, it was demonstrated that maintaining an optimal frequency while cycling can reduce the effort and help cover a longer distance in less time.

To reach the right pace for you, do some experiments and ride on a path you already know counting how many times you pedal in 15 seconds. Multiply the result by four and if the value is too low, you can use a more “agile” pedaling by switching to a gentler gear. On the contrary, you can use a harder gear if the value is too high.

Factors That Influence The Choice Of The Gear

Now that you know there is a right cycling pace, you might wonder how to understand when to change the gears depending on the characteristics of the path or road you cycle on. It is difficult to answer this question, because the choice of the gear, beyond all technical considerations, is personal and influenced by multiple factors.

  • Your physical shape is the first factor that influences the choice of the gear. If you are fit and used to work out, then you can probably start cycling using one of the most challenging gears without considerable effort. On the contrary, you might struggle to get your bike moving even on the softest gear if you are not in a great shape.
  • Along with your physical shape, the cycle training is another factor that will weigh on the choice of the gear. In many cases, being physically fit is not enough and to achieve an efficient cycling on any setting it is usually required specific cycling training.
  • The gear system itself is another factor to consider. Different bikes come with various gear types, and the differences can be easily noticed between the bikes designed for different disciplines. In poor words, a mountain bike will certainly have a different transmission and gear system compared to a road bike or urban bike. Nonetheless, the technical innovations have improved the quality of the transmission systems on all types of bikes and the most basic models now boast at least standard double chainrings with 11 rear sprockets. The choice of the bike gear system has a great influence on the riding style and on the choice of the ratio from the available options.
  • Another factor that influences the choice of the gear is the condition of the ground you’re cycling on. There isn’t much to say about asphalt, that provides a perpetual grip, but things are slightly different in the case of the off-road cycling. For example, even if you are riding on a fairly flat terrain, if there is a lot of mud it is recommended to use a more agile ratio which tends to provide a better grip.
  • Lastly, the choice of the gear is also influenced by the smoothness of the tires. Practically, if you want to decrease the effort, it is recommended to use less rugged tires and to inflate them to higher pressures. This usually narrows the section of the tires, reducing the footprint and allowing you to use a higher ratio.

Tips For An Efficient Change Of Gears

Now that you know how bike gears work, you should also find out how to maintain the gear system in the best conditions.

  • Check the derailleurs regularly: the derailleur is the mechanism that moves the chain from one chainring or sprocket to the other, therefore you should make sure that it is kept in the best conditions. Especially if your chosen discipline is mountain biking, after each ride clean any mud or dust residues from the derailleurs. If you are practicing road cycling, or even for casual commuting in the city, it is still recommended to check and clean the derailleurs regularly to avoid any flaws of the system. In fact, the derailleur adjustment tends to bump if not maintained properly.
  • If you are practicing road cycling, or even for casual commuting in the city, it is still recommended to check and clean the derailleurs regularly to avoid any flaws of the system. In fact, the derailleur adjustment tends to bump if not maintained properly.
  • ​Lubricate the chain: apart from the derailleurs, the condition of the chain also has an impact on the gear changing ease. If not lubricated regularly, bicycle chains tend to rust. Dirt and mud also accumulate with ease in the spaces between the chain elements, therefore it is essential to clean the chain regularly and lubricate it at least once a month.
  • ​Plan in advance: bike gears are meant to be used differently on flat terrains, uphill or downhill paths. For this reason, it is important to change the gear in advance, as soon as you notice that the characteristics of the path will change. This rule is important, especially when riding uphill or downhill because on this type of terrains it is harder to change the gear due to the pressure applied to the system.
  • ​Do not change the gear under pressure: the transition between the gears should be made while you are cycling at a regular rhythm, and not when you struggle to ride uphill or to maintain the speed in downhill. The reason for this is because the gear system is rather delicate and if you apply a high pressure on the pedals while changing the gear, the derailleur can break or the chain can slip off the chainrings or sprockets.
  • ​Pedal when changing the gear: gear shifting is meant to be done when the chain is rotating, therefore you have to pedal when changing the gear. Failure to do so can have the same effects as changing the gear under pressure and it can damage the chain or the gear system.
  • Check the cables and sheaths regularly: to change gear, a system of cables and sheaths action the front or rear derailleurs every time you switch the shifting levers on the handlebar. Therefore, when checking the status of your gear system don’t forget to check the status of those cables and sheaths as well. The cable system tends to rust quite easily, it must be lubricated regularly and it is advisable to completely change it every year.


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