How the planetary hub of a bicycle works
Choosing a bike with several speeds, the buyer is often faced with a variety of incomprehensible terms. In this article we will try to figure out the issues of gear shifting and planetary hub.
There are currently two types of gear shifting: the classic scheme with derailleurs and the planetary hub.
Planetary hub. closed gearshift system for the bike, the whole mechanism is inside the rear hub. The design is reliable and durable. Simple planetary hubs have 3 speeds, the most advanced models have up to 14 gears.
Planetary hubs were most popular in the first half of the 20th century, almost every bicycle had such a hub (they were especially popular in Great Britain, Holland, Germany, Scandinavia). However, the speed switches and cassettes that appeared later replaced the planetary hubs, due to their low cost and unpretentiousness.
The planetary hub bike does not have an external derailleur. the entire shifting mechanism is hidden inside the rear hub, and outside there is only one sprocket and chain. This is the most important advantage of planetary hubs. there are no unnecessary parts that are so easy to damage if dropped. The entire shifting system is located inside the hub body, reliably protected from dirt and external influences. Shifting can be done both under load and without, since the chain is in the same gears all the time, there is no likelihood of its damage when shifting. Unlike the classic shifting system, the planetary hub is compatible with the rear coaster brake.
The peculiarity of planetary bushings is higher cost and lower maintainability than a classic shift system. A sophisticated shifting mechanism inside the hub is more expensive than a classic shifting system.
The planetary hub is reliable, with proper operation, the resource is tens of thousands of kilometers. The drive uses thick chains and sprockets, and their service life is many times longer than that of comparable bike components with a classic derailleur. The planetary transmission does not require maintenance, the only adjustment is the cable tightening during operation. However, if something breaks in the planetary hub, the repair can be expensive and will have to be done in a specialized workshop.
Despite the large number of speeds in the most advanced models, not all types of riding will have enough planetary hub speeds. Such a gearshift system is suitable for unhurried, comfortable riding in the city, forest and parks. But if we are talking about cross-country riding or more extreme cycling, then the number of speeds and gear range will not be enough.
It is worth noting that the weight of the planetary hub is much higher, when compared with the classic gear system, the weight distribution of the bike will be shifted towards the rear wheel.
long resource with proper operation
the gearshift mechanism is completely enclosed in the hub housing to protect it from dirt
Shimano Nexus Alfine 8 speed How it works
Compatible with both hand brakes and rear coaster brakes
If you need a bike for a quiet ride in the city and parks, you do not chase the number of gears and want to have a reliable bike without unnecessary parts and easy to use, then the planetary hub is exactly what you need.
The most common option. this is a classic switching scheme with cassette and switches. The rear hub has a set of sprockets called a cassette and an external derailleur attached to the frame via an adapter called a cock. On multi-speed bikes (over 7 speeds), there are also two or three stars in the front and an external front derailleur.
The total number of gears is the number of stars in the front system multiplied by the number of stars in the rear cassette. For example: 3 forward and 9 reverse gears add up to 27 speeds. But in fact, it is impossible to use all combinations and is even contraindicated, since it will lead to premature wear and equipment breakdown. To avoid distortions of the chain, thereby eliminating the likelihood of breakage, it is usually recommended to use such combinations as: 1×1,2,3, 2×2,3,4,5,6,7,8, 3×7,8,9.
The classic circuit with switches is the most common and affordable. A suitable system or individual spare parts can be selected. The main plus is that it is easy to repair it if it breaks down or to upgrade to a more advanced one. But there are also a few drawbacks: the rear derailleur is attached to the right side of the frame and is easy to break if the bike falls on its right side unsuccessfully. Also, the system is demanding on cleanliness, since all components are open, it is necessary to clean the components and lubricate the chain in order to exclude its premature wear. It is necessary to learn how to switch gears correctly. in no case should you switch under load. It is always necessary to change gears in advance and at the time of shifting it is necessary to press down on the pedals not too much to avoid breaking the chain. This shifting system is not compatible with the rear foot brake.
If you follow the rules of switching, keep the bike clean and do the necessary maintenance in a timely manner, then the classic switching system will delight you with high-quality and reliable work.
If you choose a mountain bike or you need excellent maintainability, then there is only one choice. classic gearshift system.
What is the principle of the planetary hub.
It uses a simple planetary epicyclic gear train.
Let’s try to understand the operation of this mechanism at least at the level of a general understanding of the operation of the three high-speed planetary.
The sun gear (light yellow part in the picture) is rigidly attached to the hub axle, which in turn is attached to the bike’s dropouts. Three. four identical planetary gears (blue details in the picture) mesh with the sun gear, rotating around it.
The planetary gears attached to the planetary ring (light green part) mesh with the teeth on the inner surface of the gear or epicycle. This is the pink part in the picture with the teeth inside.
When the planetary sleeve (blue) rotates, the gear (pink) rotates 4 times for every 3 revolutions of the planetary sleeve. This ratio is different for different models of planetary hubs.
There was an explosion in bicycle design in the 20th century.
Inventor / Developer: Miscellaneous
The 20th century saw a real explosion in bicycle design, although they are all heart, simple variations on the safety bike. There have been minor additions to the bike from gear to suspension, as well as improvements to the tire design such as adding treads.
The 1970s saw the so-called bicycle boom in America as the general public realized the value of exercise and energy efficient transportation.
The bicycles are lighter and stronger and have a more aerodynamic design. Notable developments include recumbent, BMX and mountain bikes, with the latter being one of the first to eliminate the need for smooth surfaces.
Birth of Velocipede / Boneshaker
Inventor / Developer: Pierre and Ernest Michaux / Michaux Company
The bike was a two-wheeled bicycle with cranks on its front wheel, which consisted of a combination of a wooden frame with metal tires, making it very uncomfortable to ride the cobbled streets.
It was invented in France sometime in the 1860s and was first produced by Michaux between 1867 and 1869. Velocipede will lose popularity soon after.
Because of this design, it quickly earned the nickname Boneshaker. a name that will stand the test of time.
The first bike could be Chinese.
Inventor / Developer: Lu Ban
Back in 2010, a Chinese historian created a recreation of what he believed could have been invented 2,500 years ago by Chinese inventor Lu Ban, which is believed to be a large wooden device with intricate mechanisms and pedals to make it move, and technically speaking, it was a tricycle.
His findings have yet to be verified and accepted by his peers, but it’s definitely an interesting device.
Why Scientists Usually Talk About Mass, Not Weight?
The weight of an object depends on its mass and the force of gravity. The strength of gravity depends on how far one object is from another, which is why the same object weighs different amounts on different planets. Sometimes it is easier to compare planets using less complex measurements. This is why scientists and engineers often measure the mass of an object. how much substance the object contains. not its weight.
The mass remains the same regardless of location and gravity. You will have the same mass on Mars or Jupiter as on Earth.
Your weight on other planets is different due to gravity, but your mass is the same everywhere!
.972 How a three-speed hub works
BASIC FUNCTIONAL REQUIREMENTS: Provide the cyclist with the ability to select three different gear ratios in the bike drivetrain
DESIGN PARAMETER: 3 speed hub (this is one of the possible design parameters)
GEOMETRY / STRUCTURE AND PARTS:
3-speed bicycle hub
|3-Speed Hub Components|
EXPLANATION HOW IT WORKS / USED:
|Section Planetary Gear System|
Three-speed hubs use a planetary gear train to achieve a gear ratio between the sprocket and the wheel. In this gear system, the sun gear is locked in place and the quarry planet rotates. This causes the planetary gears to rotate, which in turn causes the ring gear to rotate.
|3-Speed Hub Cable Lever|
The rider selects the speed using the gear selector. The switch pulls on the cable that is connected to the cable lever. This causes the cable arm to rotate.
|Animated two-dimensional cross-sections of three speed concentrators|
The cable lever presses on a pin through the axle This pin is connected to the planetary gear and causes it to move from side to side when the lever is depressed.
When shifting the planetary system from side to side, the ring gear and planetary carriages engage or disengage from the wheel and chain. This is what changes the gear ratio.
Animated 3D cross-sections of three speed concentrators
|3-Speed Hub Components|
gear ratio between sprocket and wheel 4: 3
(for every 4 turns of the sprocket, the wheel turns 3 times)
The gear ratio between planetary carrier and ring gear can be calculated based on the number of teeth on the sun gear and planetary gear:
|3-Speed Hub Components|
|Rotational speed of the ring gear||glad / s or|
|Planetary carrier speed||glad / s or|
|Sun Gear Teeth||–|
|The number of teeth of one of the planetary gears||–|
|The gear mechanism must fit the bicycle hub.|
|It should be lightweight so as not to add weight to the rest of the bike.|
|Since it is part of the bike’s drivetrain, its efficiency is strongly influenced by that of the entire bike. Good bearings are essential! Typical efficiency for internal components in good condition is between 94% and 98%.|
PLOTS / GRAPHICS / TABLES:
WHERE TO FIND THREE SPEED HUBS:
Three-speed hubs are mainly used on bicycles made before the 1970s
Modern internal gear hubs are based on this design, but use multiple planetary gears connected together to achieve a higher number of speeds. They are most often found on bicycles that are used in:
- stop and go through traffic because they can change gears when the bike is stopped (as opposed to derailleurs)
- harsh environmental conditions where open switches can be damaged
LINKS / ADDITIONAL INFORMATION:
Internal gear hubs. http://www.sheldonbrown.com/seven_speed.html
Planetary gear drives. http: // www.cs.cmu.edu/People/rapidproto/mechanisms/chpt7.html#HDR123
How the 14-speed hub works. http://www.rohloff.de/english/products/speedhub/speedwork.html
What is the ratio of gravity to weight?
The gravitational attraction of the Earth. it is what keeps the moon in orbit around our planet. Voyager 1 captured this image of the Earth and the Moon from 7.25 million miles away. Credit: NASA / JPL-Caltech
When you stand on a scale, it actually measures how much Earth’s gravity is acting on you.
If you were to step on the scales on another planet, they would say something different from here. This is because the planets weigh different amounts, and therefore the force of gravity from planet to planet is different.
For example, if you weigh 100 pounds on Earth, you will weigh only 38 pounds on Mercury. This is because Mercury weighs less than Earth, and therefore its gravity affects your body less. If, on the other hand, you were on heavy Jupiter, you would weigh a whopping 253 pounds!
How it works and what it consists of?
The mechanism includes the following elements:
- sun gear rigidly coupled to the wheel axle;
- planetary gears, or satellites;
- carrier. connects and fixes satellites;
- epicycle. ring gear.
Outside the transmission housing is a single sprocket connected to the mechanism via a spline drive. When shifting gear with a handle on the steering wheel, it changes the speed of rotation of the carrier relative to the epicycle.
The simplest type has three gears, which work as follows:
- Low. the epicycle engages with the satellites that rotate the sun gear. For every 4 revolutions of the sprocket, the wheel makes 3 revolutions.
- Straight. the epicycle is directly connected to the sun gear, bypassing the gears, thereby achieving a 1: 1 ratio of wheel and sprocket rotations.
- Increased. When it is turned on, the mechanism works the other way around. the sprocket transmits force to the planetary gears, which rotate the epicycle, the moment from which is transmitted to the sun gear. Due to this, the transmission is increased by 33-36%.
Depending on the number of gear satellites, there can be from 3 to 14, but the most common are planetary bicycle hubs, the device of which provides 5 or 7 speeds.
[attention type = green] But if you are just going to buy a bike, you will also have a difficult task: which one to choose. You can give preference to one of the mountain models, or try to pick up a tricycle for the elderly if you are already of an honorable age. [/ Attention]
To learn more about how bicycles with a planetary hub work, the video will help.
Features of Planetary Bike Hub
Gear shifting is used on almost all types of bicycles. This mechanism is located on the rear wheel. One such type is a planetary bicycle hub. How does it work and is it worth using it?
Advantages and disadvantages
The planetary gearbox has the following advantages:
- low chain and sprocket wear;
- high reliability and durability of the mechanism due to protection from external influences and constant lubrication with gear oil;
- no need for adjustment;
- ease of gear shifting. you can do this both on the go and while standing still;
- no risk of damage to the transmission mechanism when the bike falls on its side;
- the ability to install a foot brake;
- reduced likelihood that the chain will fly off the sprockets;
- a wide variety of gear ratios. up to 520%.
The disadvantages of the mechanism include:
- large mass, reaching 3 kg. In addition, weight is unevenly distributed between the front and rear wheels;
- the complexity of repairing and installing the planetary hub on a bicycle; mounting on an existing bike is completely impossible, even if you use a special tool and a rear wheel stand to simplify the work. In the event of a breakdown, you will either have to buy a new hub or a new bike. Therefore, installing a planetary hub on a bicycle with your own hands is a difficult or almost impossible process;
- low efficiency of the gearbox associated with the increased coefficient of friction of the gears. Because of this, these transmissions are not used on sports bicycles;
- limited torque. Although the range of upshifts is wide, it will not be possible to engage in a low enough gear to enter a very steep hill;
- high price.
Thus, the planetary will be a good choice for walking, city and other types of bicycles for a leisurely and comfortable ride. If the bike is used for racing, cross-country riding or downhill, this mechanism is more likely to be a burden than an improvement.
This table shows the four main manufacturers.
|Rohloff||Includes 14 planetary hubs, due to which it can compete with cassette transmissions in terms of the number of gear ratios.|
|SRAM||Various hub models have up to 12 speeds, which provide an increase in the gear ratio of up to 420%.|
|Shimano||Wide range of mechanisms. from simple 3-speed to 11-speed units.|
|Sturmey-Archer||A set of hub models with 3-7 speeds is complemented by hybrid mechanisms combining a planetary transmission with a cassette.|
The price of a planetary bike hub is quite high. It depends on the complexity of the mechanism. So, a 14-speed Rohloff hub costs from 53 to 89 thousand rubles. depending on the model. Much more affordable transmission Shimano. from 2700 rubles. for a 3-speed device up to 21 thousand rubles. per model with 11 gears. for SRAM mechanisms start at 5000 rubles. Sturmey-Archer products will cost 4,700-10,500 rubles.
Reviews for bicycles with planetary hubs indicate that this type of transmission fully realizes its advantages in most operating conditions. Users do not have to worry about repairing and adjusting the mechanism, the bushing can work for several years without any problems.
In addition, the lack of low gears does not affect the use of the bike in any way. you can safely enter even a steep hill.
Planetary bicycle hub, device and principle of operation
Optimum speed, smoothness of movement, cadence, load on the bike. all this is the responsibility of the bike transmission. The planetary hub is a complex mechanical system that is used to change speed modes. This mechanism has both admirers and critics, as a result of which it is advisable to get to know it better.
A gear mechanism is located inside the body of the device, the purpose of which is to change the gear ratio. The device characterizes itself as a durable and reliable mechanism. This bicycle drivetrain is fundamentally different from the classic, which involves the use of a sprocket. Due to the mass of positive qualities inherent in the mechanism, interest in planetary hubs from cyclists continues to grow.
A set of positive qualities inherent in a planetary hub allows it to be equipped with bicycles intended for city trips. Advanced bikes like the Dutch bike are equipped with seven-speed hubs, while simpler city bikes are equipped with three-speed hubs. The mechanism itself is hermetically sealed by the bushing body. all internal elements of the mechanism are in oil. Due to the heavier design of the bike, planetary hubs are used as a transmission element mainly on city bicycles, where the number of obstacles is minimal.
Service of the planetary hub
Despite the complex design, the device rarely fails. An impressive service life characterizes the device from the advantageous side, increasing the number of admirers. Failure to follow simple rules of use can lead to premature bushing breakage. In case of failure of the mechanism, you will need to contact a specialized service center, where specialists will quickly fix the breakdown. Maintenance of such a mechanism requires the intervention of specialists, since all rotating elements are located inside, in an insulated and oil-filled housing. Attempts to self-eliminate the malfunction of the mechanism often lead to irreparable damage, which affects the family budget.
The manufacturers managed to produce a comfortable folding bike for everyday use. The model is suitable not only for city trips. walks in the fresh air on dirt roads will also be comfortable. The folding bike is able to overcome bumps, bumps and other off-road elements. A foldable bike with a planetary hub performs well when riding on hilly terrain, where the number of ups and downs is unlimited.
This model is equipped with a 3-speed hub. The RWD hub has impressive performance potential. The great advantage of the Shulz folding bike is the ability to adapt it to a child or an adult. The model is suitable for driving in mountainous areas.
The folding model in question is made from an MTV and a bike designed for one speed. The model is designed primarily for trips in mountainous terrain: the bike is able to overcome descents and ascents, as well as uneven terrain. The bike is equipped with a Shimano Alfine SG-S700 hub. as well as a pair of disc brakes. This decision of the manufacturer allows you to easily adapt the ride to any terrain.
Read more about folding bicycles with planetary hub here
Equipping a regular bike with a hub
In order to make an ordinary bicycle modern and adapted for walking on different terrain, a hub is possible. To do this, you need an installation complex consisting of a sleeve, fasteners and a shifter. If there is no desire to do an independent wheel bulkhead, there is always an alternative. buying a ready-made wheel with a built-in planetary hub. Nexus SG-3C41 is an acceptable hub model for two-wheeled vehicle retrofitting.
Once you have the wheel, get to work on the bike conversion. First of all, you need to swap the wheel fixing nuts. For safe transport, the installation of the nuts is reversed. A blind cap nut is located on the side of the washer, while the usual one should be located on the right side of the switch. Further, the sequence of actions will be as follows:
- First, you need to turn the bike upside down, then remove the wheel to be replaced
- It is better to rearrange the tire with a rim tape. For a double rim, a polyester tape is required, since the rubber will fall into the rim holes
- Now you can start installing the new wheel. The yellow washer must be pushed onto the axle from the brake lever side so that the protrusion of the washer engages in the wheel axle eyelet. The yellow washer serves to keep the wheel axle from turning under the influence of the moment during the operation of the gearbox
- Attach the brake lever to the bike frame and then adjust the chain tension. Tighten the nuts
- You can put the two-wheeled vehicle in its original position. wheels down
- Now you need to put the shifter on the steering wheel, draw the cable to the rear wheel. Use cable ties to secure the jacket to the frame. This action is performed every 25 cm
- The spring engages first gear. Place shifter in position 1
- The stem is lubricated with grease and then inserted into the axial bore. Now you need to put the carrier on the axle, while pushing the rod into the bushing. Do not apply too much pressure as the stem bends easily
- The carrier is pushed onto the axle until it stops, then it is fastened by means of a screw with a wrench for 8
- Flip the bike with the wheels up, check the gear shifting. Crunching and other extraneous noise interference should not be heard during testing. Exception. clutch ratchet sound
At the end, you will need to check the cable routing. Tighten the zip ties and enjoy the privileges of an upgraded bike.
All bicycles with planetary hub
Today, many companies are engaged in the production of bicycles with a planetary hub: Ardis, GHOST, Begramont, Comanche, etc. Therefore, the list of bicycles that comes with the mechanism in question is quite large:
- Bergamont Horizon N7 CB Gent 2018
- Comanche lago
- VNV Goodway 20 2018
- Winora Jade 2017
- DRAG 24 Prima 2017
- Winora Holiday Gent 2018
- LikeBike Laguna
- Apollo Neo 20 3i Girls 2018
- Ardis Vintage CTB 26
- Dorozhnik Cruise 2018
- Scool chiX Pro 26 3S 2015
- ORBEA Katu 40 2018
- GHOST Square Urban 4 2016
- Felt Bixby
- Pride Rowdy 2.1 2019
- Giant Simple Three 2016
- Head City 7G 2018
- Winora Lane Monotube 2018
- Le Grand William 5 2016
- Winner Ibiza 24 2018
- Dorozhnik Comfort Female Planetary Hub 28 2018
- Pride Sophie 4.2 2018
- Graziella passion
- Kellys Lumi 70 2018
- Kreidler Vitality Eco 2
- Felt Squealer
- Lapierre Urban 400 2018
The above is an incomplete list of bicycles equipped with a planetary hub.
Device and principle of operation (with pictures)
The bushing functions like an automobile gearbox. The system allows you to change the intensity of the bike’s movement at the right time and extremely quickly. The bushing device is represented by a number of elements:
- Sun gear
- Planetary gear
- Rear sprocket
- Planetary clip
The mechanism in question is an essential component of a bicycle drive system. The operation of this device is based on the complex principle of a gear mechanism that changes gear ratios. The gear adjustment process is carried out using the selector knob. The principle of operation of the planetary is worth examining more specifically:
- The cogwheel is driven by a rear sprocket (in low gear). The planetary cage is used to move the sleeve, reduce the speed. The wheel makes 3 turns for every 4 sprocket turns. At this point, the gear is down a quarter.
- Direct transmission provides for the movement of a gear wheel under the influence of a sprocket. The gear wheel moves the planetary gear, as a result of which there is a direct transmission
- High gear means the transfer of power from the sprocket to the clip. Under the influence of the force, the gear wheel begins to move. The wheel turns 4 times for every 3 revolutions of the sprocket. At this time, the transmission is increased by a third.
Some hubs are equipped with reverse gear, which is a very useful solution for tricycles. Some mechanisms can boast of 14 speed modes, but the cost of such devices turns out to be quite high. Along with the bushing, it is allowed to install a chain guard.