Bicycle sleeve

The hub of a bicycle wheel (expanding sleeve ) is the central part of the wheel that rotates around a fixed axis on bearings .

Content

Design

The classic hub consists of a housing with flanges to which the wheel spokes are attached. Cups are pressed into the ends of the housing where bearings are inserted. Bulk ball bearings, open bearings with a cage, and sometimes sealed bearings (industrial bearings) are most often used. The bearings are attached to the axis by cones, which are tightened and fixed with locknuts. The rims of the wheels are fastened, as a rule, by means of knitting needles, but in special designs they can be fastened with the help of blades, discs, etc.

Types of bushings

Front

The front hub is extremely simple in design, because all that is required of it is the rotation of the wheel. Some bushings on the left side may have a brake disc mount.

Back

The rear hub ( English freehub ) has a more complex design, as it is part of the transmission . If there is a thread on the right side, then such a sleeve is designed to install a ratchet - a system of rear stars with an overrunning clutch . The sleeve for mounting the cassette has a ratchet attached with a hollow bolt in the form of a spline drum, on which the rear stars are worn. Such a system is much more reliable than a ratchet, and when the stars wear, you do not need to change the entire ratchet mechanism, since it is located inside the hub drum. On the left side, some models may have a brake disc mount.

In Soviet bicycles brake linings were often used, the braking of which was carried out by turning the pedals back. The main disadvantages of such a sleeve is the complete deprivation of the ability to brake in the event of a chain subsidence, as well as incompatibility with the rear derailleur.

The rear hubs can also have an integrated planetary gearshift mechanism. However, the above disadvantages do not preclude the use of this type of hubs on modern city bicycles of leading manufacturers, as well as on electric bicycles.

Gallery

Ratchet bushing
Cassette sleeve
Planetary gear hub
Disassembled brake sleeve
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Brake bushing assembly
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Front hub with disc brake mounts