The rear bike wheel is an inseparable part of the bike transmission since it is connected to the pedal by the bike chain. It consists of a rim, a Bicycle Hub and spokes. It is equipped with a hub wider than the front wheel, since the latter contains a space dedicated to the gears to hold the chain and change the speed of the bike.
The types of bicycle hub
Around the axis of the bicycle hub of the rear wheel, are the body of the hub which has flanges, large or small, on which attach the spokes. And in the part called the bowl, steel or ceramic ball bearings blocked by cones that allow the body of the hub to rotate around the axis.
Disassembly and maintenance of the hub is done using a flat key for hub cones and professional grease as you can see on this video of the maintenance and adjustment of a traditional hub:
Some hubs also have a space with 6 threaded holes to accommodate a brake disc such as this Shimano Disc Brake MTB Rear Wheel.
Bike wheel hub for threaded holes
- The freewheel
The free wheel is the basic transmission system present on most old bikes and children’s bikes. It is screwed on the bicycle hub with a thread which is called a freewheel body. It is an assembly of integral gables of one another forming a single block.
- Single-speed freewheeling the single-speed
freewheel is the simplest of the transmission systems, since it only contains one speed. Mainly used on children’s bikes and BMX, it is however more and more present on fixie and city bikes because it requires much less maintenance than a bike with a complete transmission.
The single-speed bike has the advantage of being lighter and also ensures the absence of twisting of the chain by a chain line that can be adjusted to the millimeter in order to obtain the most efficient transmission. Mono-speed bikes are also less noisy. The freewheel is composed of a body accommodating ball bearings and a set of teeth in several sizes:
- Freewheel pinion 16 teeth
- Freewheel sprocket 17 teeth
- Freewheel sprocket 18 teeth
- Freewheel gear 20 teeth
- pinion freewheel bicycle one speed
- The freewheel from 3 to 8 speeds
The freewheel system comes in several versions:
- 3 speeds freewheel
- 5 speeds freewheel
- 6 speeds freewheel for bike
- 7 speed bikes freewheel
- 8 speeds freewheel
The advantage, when mounting this system on its transmission, is that it is a single block. It is not necessary to mount the gears one by one. It should be known that the lengths of axes and threads are not identical on the wheels. For example, a wheel for freewheeling 3 speeds can not necessarily accommodate a freewheel 7 or speeds.
Tool to dismount freewheel bicycle
It will also require the chain whip to lock the gears during disassembly. The free wheel with handle can also be practical if the wheel has a quick tightening, this tool is equipped with a guide to facilitate disassembly.
- The cassette
Cassette for bicycle stacking sprockets
The cassette bicycle hub differs from the freewheel by its sprocket stacking system. It has a splined shaft integral with the rear wheel called cassette body. This type of hub is found on the majority of modern racing bikes. The advantage over the freewheel is that its stiffness on the axis of the wheel allows to have a larger number of gears (up to 12 speeds for some mountain bikes). On some cassettes, you can change the gears one by one, when they wear out or you want to change the toothing or staging speeds.
- The bicycle hub with integrated speeds
More and more, we find, especially on city bikes, transmissions where the speeds are integrated in the rear hub. Especially present on electric bicycles, folding bikes, and self-service bikes, the integrated gear hub has many advantages over a conventional transmission. The first being the possibility to change gears when stopped. But also, because the shifting is done inside the case, it allows not to derail, to avoid rapid wear and corrosion. Speeds are also much smoother than on an external derailleur.
This type of transmission comes in several versions with a number of different speeds, it is also popular among user’s coaster wheel.
- Coaster hub
The coaster hub incorporates a brake that allows braking by pedaling back with a drum brake.
The brake is inside the bicycle hub and allows you to avoid using your hands to brake. This system has the advantage of being particularly reliable, its service life is very long, and does not require any specific maintenance. The mechanism being inside the hub, it is protected from bad weather. Braking is also more powerful because the force exerted by the foot is greater than that of the hands.
Mounting is done with a coaster collar for a coaster wheel mounted on the hub rod that attaches to the bike frame at the rear base. It has the advantage, compared to the pad brakes, to have no cabling up to the handlebars.
- The “flip flop” wheel
The 2000s saw the arrival of a new type of hub, used by the couriers: it is that of track bikes where the pinion is secured to the rear wheel. It is called fixed gear. It allows pedaling forward and backward but cannot stop pedaling as with a conventional freewheel. This type of hub has become very popular, because the bikes become completely refined, some even without brakes.
The hub consists of a clockwise thread on which a fixed gear is screwed and a second anti-clockwise thread on which is screwed a lock nut which prevents the pinions from unscrewing.
This type of hub is now available in multiple versions. There are double-threaded hubs called fixed / fixed to be able to put two gears of different sizes to have a different development and hubs with a double-threaded side for fixed gear and nut and the other with a single thread for a wheel free classic. This wheel is called flip flop. Simply turn the wheel to go from freewheel to fixed gear or vice versa. It is recommended for this type of wheel not to take into account the direction of tire rolling.
Examples of flip flop wheel:
White fixie wheel
Pair of black flip flop bike wheels
Pair of orange flip flop wheels
Front and rear blue flip flop bike wheels
Pair of green flip flop wheels
Choosing a suitable rear wheel hub for cycling, whether urban or rural, daily or occasional and depending on the environment is a key element of the cyclist’s comfort. The single-speed freewheel, coaster and integrated speed hub will be more suitable for urban and occasional practice while the freewheels and cassettes at high speeds will be more suitable for a so-called “sports” practice of the bicycle.