A gear case, also known as a chain case or chainguard, is an enclosure for the

bicycle chain A bicycle chain is a roller chain that transfers power (physics), power from the Bicycle pedal, pedals to the Drive wheel, drive-Bicycle wheel, wheel of a bicycle, thus propelling it. Most bicycle chains are made from carbon steel, plain carbo ...

and

sprocket A sprocket, sprocket-wheel or chainwheel is a profiled wheel A wheel is a rotating component (typically circular in shape) that is intended to turn on an axle Bearing (mechanical), bearing. The wheel is one of the key components of the whe ...

assemblages commonly employed by

utility bicycles A utility bicycle, city bicycle, urban bicycle, European city bike (ECB), Dutch bike, classic bike or simply city-bike is a bicycle designed for frequent short, moderately paced rides through relatively flat urban areas. It is a form of utility ...

. It serves to protect the cyclist from being soiled or trapped in the chain rings and tends to fully enclose the drive train. It may also contain an oil bath to keep the chain lubricated. Modern examples are usually moulded in

plastic Plastics are a wide range of synthetic polymers, synthetic or Semisynthesis, semisynthetic materials composed primarily of Polymer, polymers. Their defining characteristic, Plasticity (physics), plasticity, allows them to be Injection moulding ...

. Similar devices may be found in connection with chains used on larger vehicles and machinery.

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References

bicycle glossary entry for "Chain case"
from Sheldon Brown's website
Sheldon Brown's bicycle glossary entry for "Gear case"

Bicycle parts {{cycling-stub

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See also

References