Gear case

A gear case, also known as a chain case, is an enclosure for the bicycle chain and sprocket assemblages commonly employed by utility bicycles. It serves to protect the chain from mud and dirt 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. Similar devices may be found in connection with chains used on larger vehicles and machinery.

There are also a variety of smaller structures called chainguards which, rather than protecting the chain, serve only to protect the rider's clothes from being soiled or trapped in the chain rings.

Gallery

[[|center|border|240x180px|alt=|European city bike with fully enclosed chain ]]
European city bike with fully enclosed chain  
European city bike with partially enclosed chain  
BMX bike with a chain guard bolted to the frame  
Crankset with an integrated chainguard bolted to the outside of the largest chainring  

References