Chain guard

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A chain guard or chain case is a component on two-wheelers and certain machines that on the one hand protects the driver or user from contact with the chain and the resulting injuries and dirt and on the other hand shields the drive chain from dirt and other environmental influences.

bicycle

In the case of bicycles, the dirt thrown up by the road can adhere to the lubricant of the chain and together with it form a type of abrasive paste that penetrates the chain's joints and accelerates their wear. In addition, an exposed chain can come into contact with clothing and contaminate it. In the worst case, a part of a garment, such as B. a pant leg, get between the chain and the sprocket and get caught there, which can lead to a fall. The chain guard thus also serves to prevent falls . Depending on the type of bike, different types of chain guard are used:

  • Full chain guard

  • Full chain guard

  • Open chain guard

  • Recumbent bike with chain protection tubes

  • Open chain guard "chainrunner"

  • Gear with chain guard

Full chain guard

The full chain guard or chain case is particularly found on touring or Dutch bikes. Another full chain guard is the Chainglider model , in which the chain is guided in two square plastic tubes. Both versions completely surround the chain, including the chainring and sprocket . Only a hub gears can be used as the gearshift for both , as the full chain guard would hinder the necessary movements of the rear derailleur and derailleur of a derailleur .

The advantage of the full chain guard is that it requires little maintenance and the chain has a long service life. The high amount of work involved in dismantling the rear wheel has a disadvantageous effect .
Often the full chain guard is only completely closed on the outside to make it easier to dismantle.

Open chain guard

The most common type of chain guard is a partial chain guard, which surrounds the upper part of the chain and the chainring , and thus effectively protects the driver and his clothing from contact with the chain. It is not very suitable for protecting the chain itself, as it mostly runs open in places that are more exposed to dirt from the road (e.g. behind the front wheel). For bikes with derailleur gears , the market offers models with cutouts for the front derailleur . An alternative design for a partial chain guard for gear hub gears is a slotted corrugated hose that runs with the chain, also known as a chain runner. It surrounds the chain and protects it and the trouser leg from dirt. The disadvantage is that once penetrated dirt and moisture can no longer escape. The risk of foreign bodies (shoelaces, trouser legs) being trapped between the chain and the cog is also not eliminated.

Chain protection tubes

Especially on sun gears are common chain tubes from polyethylene or PTFE , each of the upper and lower part of the chain are surrounded and fixed against slippage along the chain line to the frame. Their main task is to protect the cyclist's clothing from dirt. Since the chain slides in the tubes on the wall, there are minor friction losses in the drive.

By using chain protection tubes, "exotic" chain guides are also possible, as are often required on recumbent bikes.

If chain protection tubes are combined with closed coverings for the gear wheels and deflections, a full chain protection can be implemented. This is used on some conventional bicycles with hub gears.

The light motorcycles and scooters from the Simson company were fitted with a closed system of chain protection tubes and gear wheel covers as standard in order to extend the service life of both the chain and the gear wheels.

Chain guard washer (chainring guard)

There are chain guards for chainrings with a maximum of 48 teeth made of plastic, which can be screwed onto the crankset and mounted without dismantling the pedal. Weight approx. 90-120 grams.

Here only elementary protection of the driver's trousers is guaranteed.

literature

  • Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production. 10th edition, BVA Bielefelder Verlagsanstalt GmbH & Co. KG, Bielefeld, 1999, ISBN 3-87073-131-1
  • Richard Hallet: Bicycle Maintenance-Care-Repair. 1st edition, BVA Bielefelder Verlag GmbH & Co. KG, Bielefeld, 2003, ISBN 3-87073-308-X
  • Peter de Leuw: Choose the right bicycles, ride safely. 1st edition, Beuth Verlag GmbH, Berlin-Vienna-Zurich, 2006, ISBN 3-410-16487-1