A hub gear is a closed gear system that is integrated into the hub of the rear wheel of a bicycle. Unlike the widely used derailleur gears, where the chain is moved over various gears, the hub gear allows gears to be changed by internally adjusting gears within the hub. This design protects the gear mechanism from environmental influences such as dirt and moisture, resulting in a longer service life and reduced maintenance. Hub gears offer a fixed number of gears, which can vary depending on the model. They are particularly popular on city and touring bikes because they offer a clean, low-maintenance and reliable gear shifting experience.
What is a hub gear?
A hub gear is a type of gear used in bicycles. It is located in the hub of the rear wheel and allows the rider to change the gear ratio of the wheel to adapt the bike's performance to the road conditions.
A hub gear consists of a number of pinions arranged around the hub of the wheel and a shifting mechanism that selects the pinions. The pinions are different sizes, which means they provide different gear ratios. The larger the pinion, the greater the gear ratio, which means the wheel turns faster when the rider puts in the same amount of pedal effort.
How does a hub gear work?
A hub gear consists of a number of pinions arranged around the hub of the rear wheel and a shifting mechanism that selects the pinions. Shifting is done either by a lever on the handlebars or by turning a handle on the handlebars. This type of transmission is also called a planetary transmission. It consists of a sun gear and several planet gears arranged around the sun gear. The sun gear is attached to the input axle of the transmission and rotates when the input power (eg a motor or pedals) is transferred to the transmission.
When the rider operates the shifting mechanism, a mechanism called a shift arm moves inside the hub and selects the desired pinion. The pinion that is selected determines the gear ratio of the wheel. The larger the pinion, the larger the gear ratio, meaning the wheel turns faster for the same amount of pedaling effort the rider puts in.
Which is better: derailleur or hub gear?
Hub gears tend to be lower maintenance and more durable than derailleur gears because they have fewer moving parts. They are also better protected against dirt and moisture, making them particularly suitable for city bikes and bikes that are often used in bad weather or on rough roads.
However, derailleur gears usually offer a larger number of gears and allow for finer gear ratios, making them more suitable for road bikes and mountain bikes where frequent gear shifting is required.
Advantages of hub gears:
- No chain that needs maintenance
- Shifting is generally more precise and smoother than with derailleur gears
- Lower maintenance costs
- Less wear on chain, pinion and sprockets
- Better protection against dirt and weather influences
Disadvantages of hub gears:
- Usually more expensive to purchase than derailleur gears
- Narrower gear range (fewer gears)
- Heavier and more voluminous than derailleur gears
- Often requires special tools and knowledge for repair and maintenance.
