The material was prepared on the basis of an article by PinkBike magazine expert Mike Levy. And in the picture above you can see the gearbox from the company suntour, whose components are also used in bicycles.

Will gearboxes ever replace traditional shifters?

Pictures of the future always look very promising. from science fiction films and animated series, the levitating skateboard of the protagonist of one of the parts of the legendary film “Back to the future 2” (“Back to the future II”) has long made us understand that in the foreseeable future our life will become easier and more comfortable. to promising modern developments we can also include gearboxes for bicycles, which are not yet very supported by manufacturers of bicycle components and, as a result, ordinary cyclists. Some exclusive bike brands (such as pinion, Zerode, Nicholas) have been working in this direction for a long time, but if you go to any nearest bicycle store, you will not find a gearbox of your choice on the shelves. There is even a skeptical opinion that buyers will get flying skateboards faster than someone from major manufacturers will begin large-scale production of bicycles with gearboxes.

The Cavalerie Falcon DH seems to have it all: a nine-speed Effigear gearbox, proper head and seat tube angles, 200mm of suspension travel, and a weight of around 18kg. So why don't we all ride these bikes? Blame it on the rapid evolution of traditional switches.

Why can't gearboxes replace traditional shifters?

Gearboxes certainly have potential. You no longer have to worry about switches and a cock, which are easily damaged by stones; the reliability of modern bicycle gearboxes will make even a Unimog (Unimog - a special series of cars mercedes benz) look fragile, and the presence of only one front and one rear chainring will greatly simplify the service of the bike. Add to this the low center of gravity of a bike with a gearbox, and no need for additional shifter cables running along the frame, and you realize that these gearboxes are vastly superior to the systems we have been using on bikes for decades. But something interesting has happened in the past five years: classic switches have gotten much better thanks to innovation. And we are talking here even more about the transmission as a whole: lighter and stiffer switch frames that will not bend from a slight contact with a stone, rear bushings that can withstand the most severe tests. Evolution is a wonderful mechanism, but at the same time it weeds out the weak. In our case, closed bicycle gearboxes are the slowest antelope in the herd.

The rear derailleur from Shimano's new Zee range proved to be very reliable, and its design almost completely avoids the chain jumping off on technical terrain.

Switches become reliable ... finally

A few years ago, it was not uncommon for a situation when, with active and aggressive skiing, 4-5 switches had to be changed during the season. You could easily find yourself in a quandary because after hitting a rock, the rear derailleur would usually shatter into small pieces. In this case, the chain with fragments of the switch could have time to get into the rear wheel and damage the spokes. In general, a broken rear derailleur can set off a very nasty chain reaction. There was also an issue with axes connecting links within switches. Previously, they loosened up quite quickly (especially on inexpensive models), as a result of which it was practically impossible to set up the gears correctly. Now, regardless of the manufacturer (be it Shimano or Sram), even inexpensive models can withstand serious tests. We got to try out the new rear derailleur at the editorial office. Sram X5 designed to work with a 10 speed cassette. With a retail price of around $64, we were very pleasantly surprised. We have covered more than one hundred kilometers with him, and he is still in in perfect order. The same can be said about Shimano SLX series derailleurs, especially now that it uses technology Shadow Plus.

Mike Levy, Portal Expert pinkbike): “Despite the fact that retail prices for top-end parts are quite high, constant competition has led to last years to lower prices in the OEM segment (prices for bicycle manufacturers and assemblers). Adding an expensive gearbox to the specification would result in too much of a retail price increase for the finished bike, which would either simply not be accepted by retail customers or would have to be offset by the use of cheap components in the bike. If in the near future someone mass-produces a bicycle with a gearbox, then buying it will be akin to acquiring a greatly overpriced Toyota Prius, i.e. a kind of declaration that the owner of this machine is at the forefront of progress even in everyday things.

Chains have become much less likely to jump off the stars

Every keen cyclist who practiced downhill (downhill) 8-10 years ago can remember a few moments when he had to deal with a chain that had come off and tangled. The axles of the carriages were also easily bent at that time and brought the entire transmission into dissonance, and the chain guides were completely divided into two groups: bad and dangerous. By now, all these problems are already in the past. And modern lightweight and durable dampers from such manufacturers as MRP, e*13, Gamut etc. will keep the chain in place in almost any situation. If, of course, you install them correctly. The big breakthrough was the advent of a new generation of switches that swayed significantly less under load. Many cyclists have found that they can now use the minimalist and lightest dampeners or do without them at all. And here we should also mention the star of the new standard from Sram (although a number of other manufacturers already use a similar design) - its teeth X-sync special shape and variable thickness securely keep the chain from falling off on technical terrain.

Despite the high cost, a new group of components XX1 from Sram can finally put an end to the prospects for the mass appearance of gearboxes on bicycles. Especially if the company integrates the technology used in the XX1 into its more affordable lineups. We think that this will happen in the near future.

Less weight, more efficiency

It has long been known that chain transmission is one of the most efficient ways to transfer power. So why pass it through additional stars into switches and thus reduce its efficiency? This question may not bother freeride or downhill (downhill) fans much, but for the average cyclist who has to ride both up and down, it is very relevant. You may not be a cross-country rider, but that's no reason to waste some of your energy pedaling. Gearboxes clearly have an advantage here. What about the extra weight of the boxes? Say that he does not bother you and you are ready to put up with him, given all the advantages of a closed gearshift system? That's great, but the number of riders who are willing to give preference to a closed bike gearbox is so small compared to those who are skeptical of them that it's pointless to compare these numbers. And the lack of demand also does not stimulate the mass arrival of gearboxes.

Companies sell what is in demand

Many bike enthusiasts prefer to buy the components that professional racers on the track or freeriders use in their latest videos. When was the last time you heard a bike with an integrated gearbox win a major race? In 2006 in Rotorua(Rotorua, New Zealand) Cam Cole has won the World Championship in the Junior category, but this is the exception rather than the rule. You can also think of the old Honda cycling team, which included such famous riders as Greg Minnaar (Greg Minnaar), Brendan Fairclough and Matti Lehikoinen. They also competed on bikes with gearboxes, but sadly Honda retired from cycling after realizing that the investment was not paying off. This is not an isolated case, and for our part, we believe that in the near future we are unlikely to massively switch to frames with integrated closed gearboxes.

But closed switching systems still have prospects

Are the defenders of closed systems wrong? Is it worth developing these technologies at all, given all of the above? Yes, it is worth it, because there are undoubtedly advantages. Despite all the technological tricks and advances in classic shifting systems, closed gearboxes are still much more reliable than any shifter. You simply will have nothing to tear off with a random stone on the track. Then you can return to the issue of weight. Yes, closed gearboxes are heavier than classic shifting systems, but all the weight is concentrated in one place and engineers can optimally position the gearbox in the frame, obtaining excellent balance and a low center of gravity. Also, when using a gearbox, the rear axle of the bike will not be affected by the weight of the cassette, drum and derailleur, which will improve the efficiency of the suspension. Cost may be the last major argument against gearboxes, but here we can recall the experience of Zerode, whose engineers used an inexpensive Shimano Alfine hub as a gearbox. But is this enough for the rapid arrival of closed gearboxes to the masses? The question is still open.

Transmission and transmission system. General information

This is a group of components that transfers force from the gears of the system to the gears of the ratchet or cassette using a chain. The front and rear derailleurs adjust the ratio of the angular velocities of these gears.

Gear shift

The number of gears or speeds is determined as follows:
NUMBER OF FRONT GEARS x NUMBER OF REAR GEARS.

With strong jumps, the chain can fly off, so jumping cyclists refuse to change gears. On other MTBs and road bikes, the number of sprockets depends on the equipment level. On road bikes, sometimes the smallest star of the system is not present, since it gives the least speed.

So, figured it out. Bicycle with 21 speed has 3 front stars and 7 rear. But is it possible to use all these speeds? The answer is no! I'll explain why. All the stars in front are parallel to each other, and the same is behind. When transferring 17(small star in front and small in back) the chain will be severely bent.

Gear shifting technique

When shifting gears, you depress the shifter lever (or turn the gripshift), then pedal effortlessly, and then release the shifter lever. Pedal rotation must be idle, otherwise the chain will be taut and the derailleur will be difficult to move, it may bend.

Idea install gearbox on bike appeared back in the 19th century. But this idea existed on the drawings and in thoughts until 1915. Back then they only sold planetary hubs for a bike worth £3. For our money, this is more than enough to go nuts 🙂 The weight of such a bushing was more than 3 kilograms. In the period from the 19th century until the Second World War, gears were changed using inefficient linkage and frame systems.

This is what motivated us to create a compact gearbox for a bicycle. The first question that arose before the engineers - where to place it? It was decided unequivocally - near the carriage.

In 1935, a number of German manufacturers began producing a 3-speed bicycle gearbox that was housed in the bottom bracket. The gear lever was located in the place where the gear shifters were once installed on Soviet road bikes - at the top of the down tube of the frame. A couple of firms produced gearboxes with only two gears. Perhaps these developments would have reached their logical conclusion and the mass transition of bicycles to gearboxes, but a war broke out that broke many plans and many lives ....

What were the advantages of the gearboxes of that time?

Long service life.

Protected from dirt and water thanks to good placement.

Easy to maintain and set up.

Good weight distribution, again, thanks to the placement above the carriage assembly.

There were only a few minuses - a noticeable loss of power, which is why such boxes were not installed on road bikes, and the cost of manufacturing a gearbox wanted to be lower.

And so the war passed, a lot of time passed, and no one returned to improving the gearbox on a bicycle. Only in the early 90s, it was the development of the discipline of DH that served to modernize gearboxes. As you know, during a fast descent from the mountain, the rear caliper constantly beats against the frame and does not shift gears well. It was then that they began to come up with such a gearshift mechanism that would not be located behind and would perform its functions perfectly.

From the book "Modern Bicycle" we got the following information.

There were three main developments - the German company Nicolai, and the Japanese Hoda and SR Santur. The Germans installed an open-type gearbox based on a planetary hub. The drive had two chains, the inner chain transmits power from the connecting rods to the planetary gear, and the outer chain from the planetary gear to the rear sprocket. Honda took Shimano components as a basis and created a bicycle weighing 18 kg and with 7 gears. An external chain spins the rear wheel, while a short chain moves the redesigned rear caliper over the cassette. Santur decided not to trifle at all and created a 9-speed gearbox weighing 4.5 kilograms, which resembled a car gearbox in miniature.

The bottom line is that the developments are interesting, but expensive and made in small quantities. The book says, “But if things go well…” and it was around the year 2000. Now we can safely write in 2015 - things did not work out.

And so, for now, gearboxes have ceased their development. And what then came to replace them?

Planetary carriage.

This is something similar to a planetary hub, only it is in the carriage 🙂

There are many detailed information about the development of planetary carriages with exact dates and numbers. We do not want to load ourselves and you with this information, so we will tell you the most interesting.

The main goal of the planetary carriage was compactness and a multiplier factor. The weight of developments ranged from 1200 grams to 2000 grams along with the rods. There were developments of the Nikolai company, in which there was a magnetic gear shift drive.

The main disadvantage of all developments was the incompatibility of the sizes of planetary carriages with standard sizes carriages. But the pluses are also visible on the face. Firstly, to change gear it is not necessary to pedal, and secondly, a small chainring allows you to install a rear caliper with a short foot. It is known that such calipers are more resistant to shock and wear. Thirdly, such a phenomenon as chain skew practically disappears, which means that the service life of the chain itself increases.

Still, the planetary carriage is an interesting development, but it was the planetary bushing that received more success, which we will describe below.

planetary bushings.

History says that the first planetary hub of the modern type was born back in 1898, can you imagine? Personally, it's hard for us to imagine this 🙂 The hub had a built-in brake mechanism and several gears. Further developments went up and bushings appeared already with 3 gears. Faster and more successful bushings began to appear closer to the beginning of the 20th century. One of the most famous manufacturers is Sachs Bicycle Component, now this company is part of SRAM Corporation. It was the production of planetary bushings that turned the cycling world a little and excluded the production and development of other types of internal gear shifting.

Now there are planetary bushings in 3, 5 and 7 gears. If 5 years ago there were only ordinary bushings, so recent times planetary hubs with disc brakes and with built-in brakes have already been widely established on the market. And another difference between the old bushings and the new ones is compatibility with the front derailleur. And recently - and with the installation of a cassette on the rear wheel. That is, you have, as it were, ordinary 3x8 gears and also a planetary gear in 3 speeds. And yet, for comparison. The ratio range of the standard 3x7 shifting system is about 500%, and some Rohloff 14-gear hubs have as much as 600%. Cool, isn't it? 🙂

Brief advantages of planetary bushings:

Large range of gear ratios, as we wrote above.

Ease and smoothness in gear shifting.

High switching speed.

Ease of maintenance and elimination of the need for constant maintenance.

As well as a few downsides:

rolling.

Repair is rare, but well-aimed.

Planetary hubs have found their purpose mainly in city bikes. It's convenient and simple.
Cardan drive for torque transmission.

The advantages of a cardan shaft over a chain are enormous, and it is very strange that this type is not used now. Main advantages:

Protection from external influences.

Great reliability.

Doesn't stain clothes or snag pants.

The efficiency indicator is not higher, but it is independent of the amount of dirt and swamp on the cardan.

And here are the cons:

The cost is an order of magnitude higher.

The weight is also higher.

The cardan broke a little, but, like the planetaries, it required separate knowledge in repairing.

Impossible to install gear shifting.

Difficulty removing the rear wheel.

Modern developments have been able to eliminate a number of the disadvantages described above, especially the problem with gear shifting - the installation of a planetary hub made it possible to shift gears after all.

Belt drive.

The belt drive was used for a very long time and eventually stopped, because the main disadvantage is insufficient strength and slippage. But again, science and engineering does not stand still, and today there is a clear competition between belt and chain drive. The main disadvantage of the belt is its integrity, the impossibility of installing gear switches and the difficulty in repairing and replacing components.

Variators.

The advantage of the CVT is the stepless gear shifting and the possibility of a large gear range. But the disadvantages, unfortunately, are significant. The most important thing is the low efficiency, due to slippage in the variator itself. The disadvantages also include the loss of power, cost.

CVTs are now beginning to regain popularity due to the development of technology and thanks to the sleepless nights of engineers. The weight of the bushings used to be about 5 kilograms, and now the speed drops to 3. Let's see what happens in a few years, so far only one thing is clear - the CVTs will have a future.

And so, and now let's try to understand why all these developments did not take root? So much new, so much interesting, but everything remains: the chain and gears. Do you know why? Because everything ingenious is simple. The bike is loved by everyone for its simplicity. And there is no need to complicate things. Two wheels, frame, brakes and steering wheel, what else do you need? That is why, before upgrading your bike, think carefully about whether you need it and whether it will be useful on a bike trip.

Systems and transmissions

The constant improvement of the chain as a mechanism has made it possible to create a bicycle as it is now. Thanks to the chain drive, there was no need to sit on top of the wheel, and for better balance, the cyclist could comfortably fit between two wheels of the same size. It was the development of various gears that contributed to effective management vehicles. Now cyclists could easily conquer any climbs, even with the largest slope, and also developed high speeds with pleasure.

Transmission elements

Use of moving mechanisms

In the 15th century, Leonardo da Vinci worked on the development of the idea of ​​the joint work of teeth and a mechanical chain. Surprisingly, this idea was voiced long before the design of the first bicycle, and only four centuries later found practical application. In order for the transmission to function effectively, it is necessary to correctly transfer the force created by the rider's legs to the rear wheel of the bicycle. The design must be created so that the pedaling force does not create discomfort for the rider.

For this, engineering and technological developments were introduced, durable materials were used, which allowed the chain transmission to become a common mechanism by the end of the 19th century.

Advantages of a chain drive

The drive itself without gears functions very effectively on slopes and flat surfaces. But at the same time, a cyclist, starting from a flat surface without a speed switch or starting to climb with the wind moving on him, is forced to pedal while standing, expending considerable effort on this. At the same time, the driving speed drops to a minimum. The chain drive with gears allows the rider, regardless of the terrain, the direction of the wind, to pedal throughout the trip at a pace convenient for him. On the first bicycles with high wheels, the pedals were placed on the wheel itself, that is, one revolution of the wheel was equal to a full rotation of the pedal.

The ratio of gears can be changed by the cyclist himself at his request. For example, when conquering a steep slope, the rider can, at which the pedals will rotate easier and more often, while the wheel itself will rotate more slowly. That is, an easy transfer will be made. A heavy gear is selected when it is necessary to cross flat terrain or when going downhill: several wheel rotations occur per full turn of the pedal. In gear, the big sprocket is in the front, the small one is in the back. To spin the wheel requires a certain amount of effort and the more it is created, the more revolutions the wheel will make.

Required number of teeth

Exploratorium scientist Paul Dougherty explains the ratio of gears using the example of a personal bicycle. This method allows you to determine the number of driving (front) and driven (rear) teeth. For example, Paul suggests considering a transmission option where the gear ratio is 54:27. Based on this ratio, it becomes clear the number of teeth of the front sprocket is 54, and the rear sprocket is 27, that is, with a full turn of the front sprocket, 54 teeth pass around the drive sprocket. At the same time, the driven sprocket makes 54:27 = 2 revolutions, that is, the rear wheel turns twice. This ratio can be reduced to 2:1. But if the driven sprocket has 11 teeth, then in this case the gear ratio will be closer to 5:1.

It is worth paying attention to the fact that with each complete revolution of the drive sprocket, the driven cassette rotates twice as much.

France Twist and Penny Farthing

Paul Dougherty claims that this method of calculating the gear ratio is one of many similar ones. In the UK, the gear ratio is calculated from the diameter of the large wheel on bicycles called penny farthings. As stated above, Paul Dougherty used a 2:1 ratio. That is, when transforming twice, it was necessary to multiply the diameter of the rear wheel. This means that a 2:1 chain drive with a 27" rear wheel would be considered a 54". So, having determined the circumference of the wheel, we multiply it by the gear ratio. That is, if you use the method of Paul Dougherty with a gear ratio of 2: 1 and a circumference of the driven wheel of one and a half meters, we get the circumference of the drive wheel. It is equal to three meters. This method, unlike the English system, helps to determine the distance traveled or to understand how far you have gone.

The metric system was used in France. Metric is called decimal system units (SI), which is based on the use of grams and meters. Today, the SI system is called upon all over the world. In this system, the transformation consists in the product or division by the number 10, that is, in decimal fraction the comma is simply shifted.

When it comes to threading, the metric system indicates its pitch and diameter. The thread pitch is the distance between the threads. Take, for example, the popular M5 thread size, which is used for anchor bolts for attaching a cable, for attaching a bottle cage, in the holes for attaching a wing or trunk, gearshift levers, denoted M5.0X0.8, that is, the diameter is 5 mm, and the distance between threads is 0.8 mm.

Chain drive in transmission and its operation

A chain is a mechanism that connects the pedals to the driven wheel. Thanks to the chain mechanism, the force acting on the pedals is transferred to the rear wheel. Thus, the bicycle is set in motion.

What you should take:

In order to have a minimal idea, as well as to understand the essence of the chain transmission, you need to prepare the following items:

• several spools of thread. One coil must be either larger or smaller, and the other pair must be taken of the same size;
• rubber bands;
• flat boards of wood;
• pack of nails.

On a wooden plane, with the help of nails, spools of thread are fixed at a considerable distance from each other. It is necessary to strengthen them in such a way that when they are connected, the elastic band does not stretch, and the coils themselves can move freely and easily. After that, connect the two coils with an elastic band.

Observe how one coil behaves relative to the rotation of the other coil. What is visible? Do they move in unison, with the same speed and direction of rotation?

How can transmission be investigated?

1. It is necessary to make marks on both coils using a special marker, and then turn them. For this, two coils are used, one of which is larger than the other. So how does one coil rotate relative to the other?
2. Make one rotation on the elastic band so that it describes the eight. How did this circumstance affect the speed of rotation and the direction of movement of the coils?
3. Inspect the bike chain and derailleurs. Is there a similarity with a bicycle transmission? What is their difference?

Diagnosis of the transmission system.

The gears help the cyclist to pedal most efficiently, allowing him to easily and quickly conquer the steepest climbs and some obstacles.

What do you need to take to demonstrate the operation of the gears? What materials should be prepared:

• bicycle equipped with gears;
• a bar of soap and a roll of tape;
• a sheet of paper and a simple pencil.

Experiment

It is necessary to put the gear so that the leading sprocket is the smallest and the driven sprocket is the largest. Use a piece of tape or chalk to mark the top of the rear wheel. At the same time, the pedals should be fixed. Now you need to make a full revolution of the pedals and count and record the number of rotations made by the rear wheel.

At the next stage of the experiment, put a large asterisk in front, and a small one in the back. How many revolutions did the rear wheel make with a full revolution of the pedals? Which of the two combinations is most suitable for conquering a steep climb? And which one is effective for sprinting on flat terrain?

Conducting an experiment with a medium gear range.

To do this, you need to draw a table where the gear ratios, the number of full wheel revolutions per revolution of the pedals will be entered. Why, in your opinion, the development of such a mechanism as a chain drive contributed to the improvement of bicycles?

cadence

The cadence is called cadence. The gear system allows cyclists to maintain the most optimal rhythm of movement (pedaling speed), which makes pedaling very productive. Today, riders have different opinions about what the rhythm of cycling should be. However, the vast majority agree that cadence is the most important. From the words of Paul Dougherty: "The human body provides the largest number energy for pedaling in the most effective method at a certain cadence. I try to keep my cadence between 60 and 90 cycles per minute.”. He also notes that most recreational cyclists pedal too slowly, inefficiently, wasting energy in high gears.

Cadence for professional cyclists is very high, for road bikers it is in the range of 75-120 rpm. A completely different indicator of cadence in mountain biking.

Ruthie Matthes, World Champion Cross Country Champion, explains: “In mountain biking, you often go up a very steep hill and immediately go down a fast descent, sometimes without even pedaling. You just balance on the bike, without brakes, as fast as you can. There is a wide range and variety of cadence used in mountain biking.”