A bicycle with a planetary hub is a rather complicated mechanism, which consists of more than 40 parts and assemblies. The first vehicles of this type were developed at the beginning of the last century by SACHS and gained popularity among users around the world.
Introduction
Later, the Japanese corporation Shimano and their rivals from the USA - SRAM - improved this product and presented to the public four- and seven-speed models. Despite the fact that the planetary hub has not undergone any special changes in its history of use, the increased accuracy requirements that are imposed on its assembly and manufacture are the reason for the high cost of this mechanism. Also, the disadvantages of such a gear shifting system, in comparison with other solutions, are considered to be its low efficiency with large gear ratios.
Scope of use
Despite these shortcomings, planetary devices are very popular with discerning buyers who pick up a folding, city or road bike. After all, the mechanism protected from the penetration of moisture, dust and dirt requires minimal maintenance and provides long-term and trouble-free operation, which is combined with the following advantages:
- Bicycles with a planetary hub are presented in a huge assortment that is able to satisfy any wishes of riders.
- A wide range of gear ratios provides comfortable acceleration of the bike uphill or on other difficult sections of the track.
- Accurate gear changes are made using ergonomic shafts on the steering wheel. A gear change occurs even when the bike is stationary.
- A folding, road, mountain or city bike with a planetary hub requires minimal maintenance. Moreover, many instructions indicate that there is no need to carry out scheduled maintenance for the nodes and systems of the vilset.
- Unlike external mechanisms, which suffer from accelerated chain wear due to its skew on the stars of the system, the planetary sleeve functions in a different order. In this case, the transmission of the bike consists only of the simplest and most reliable elements that ensure continuous operation.
- The bicycle with a planetary hub is equipped with a reliable foot brake.
Design cons
Of course, the structure of this vehicle is not without some drawbacks. However, their overall influence on the final choice of inexperienced customers is too insignificant, because the bike is purchased for everyday use in the city, and there are no specific requirements for it. However, demanding critics do not forgive any flaws for these vehicles. First of all, they mention the big weight of the bike, which can be inconvenient when traveling on rough terrain, where bicycles with a planetary hub are not very convenient. The reviews of professionals confirm these theses, since the use of heavy mechanisms and units under extreme loads or sports, where every gram is taken into account, is unacceptable. Also, many cyclists reject the planetary hub because of difficulties in maintenance - if a malfunction is detected in it, it is not always rational to carry out expensive repair of the mechanism. Therefore, we will try to understand the design of planetary mechanisms and the features of their application for various needs.
Whim or need?
Almost every modern bike has a multi-stage transmission. Most often, an external gearshift system is used for the bike - this is a classic design that is easily maintained and repaired. Usually it allows switching in the range from 10 to 33 speeds, which provide the necessary gear ratio depending on the conditions. While the internal transmission of the bike, where the planetary hub is used, is still a curiosity, as is the equipping of two-wheeled vehicles with a driveshaft. Nevertheless, for urban comfort bikes, differential gear is often used, which is recommended for use only in the warm season. The application of budgetary solutions for year-round or extreme driving will only lead to accelerated wear, and a bicycle with a planetary hub will require expensive repairs. If you choose the middle price segment, you must be prepared to give at least $ 5,000-6,000 for a two-wheeled “friend”. In this case, a bicycle with a planetary hub will have a sufficient margin of safety, which will allow you to operate the bike daily.
Burden of tradition
Equally important in the selection of optimal characteristics for a city bike is its own weight. If a planetary sleeve is installed on it, reviews indicate a shift in the center of gravity of the bike to the rear axle of the fork. This observation is associated with an impressive mass of differential gear with foot brake, which can be up to 2 kilograms. Therefore, the application of this solution in compact bikes is not always justified. After all, they are designed taking into account the peculiarities of storage in cramped conditions, and excess weight is not good for them. Therefore, a folding bike with a planetary hub is an anachronism for modern society. It can be considered as a status subject of a bicycle fetish, but not a practical unit for travel.
Options
Consider the main disadvantages of the planetary hub, which limited its use in this niche:
- high risk of damage to the gear shift mechanism during its intensive operation;
- insufficient gear ratios;
- significant weight of the sleeve leads to a displacement of the center of gravity and an increase in unsprung masses on hardtail and two suspensions;
- the eccentric clamp of the wheel is not compatible with this solution, as if the fixing is not secure, the seats can be damaged;
- popular frames with vertical dropouts do not allow you to take advantage of the planetary hub, and the use of designs with horizontal leads to unnecessarily expensive bikes.
Summary
Despite the obvious disadvantages or advantages of this design, the final decision on the appropriateness of its use remains with the buyer. This thesis is confirmed in the numerous reviews of owners of bicycles with a planetary hub, who are happy to use their bikes for walking in their free time.