Product Code Database
A bicycle chain is a roller chain that transfers power from the Bicycle pedal to the Drive wheel-Bicycle wheel of a bicycle, thus propelling it. Most bicycle chains are made from carbon steel or alloy steel, but some are nickel-plated to prevent rust, or simply for aesthetics.
The first solid bush-roller patent was filed by the Renold Chain company in 1880.
Early examples of chain-driven bicycles include the 1869 Guillemot and Meyer, the 1879 Lawson, the 1884 McCammon, the 1884 Starley Rover, and the 1895 Diamant.
Before the safety bicycle, bicycles did not have chains and the pedals were typically attached directly to the drive-wheel, thus limiting top speed by the diameter of the wheel and resulting in designs with front wheels as large as possible. Various linkage mechanisms were invented to raise the effective gear ratio, but with limited success. Using chain drive allowed the mechanical advantage between the drive and driven to determine the maximum speed, thereby enabling manufacturers to reduce the size of the driving wheel for safety. It also allowed for the development of variable , allowing cyclists to adjust their Bicycle gearing on the fly, to terrain or road inclination and their strength, obtaining an efficient and workable cadence at various speeds.
An alternative approach is to change the (relatively cheap) chain very frequently; then proper care is less important. Some have fully enclosing gear case, which virtually eliminate chain wear and maintenance. On recumbent bicycles the chain is often run through tubes to prevent it from picking up dirt, and to keep the cyclist's leg free from oil and dirt.
Some newer chain designs, such as Shimano and Campagnolo 10-speed chains, require a special replacement pin to be used when installing or reinstalling a separated chain. An alternative to this process is to install a master link, such as a SRAM Corporation Power Link or a Wippermann Connex.
Since chain wear is strongly aggravated by dirt getting into the links, the lifetime of a chain depends mostly on how well it is cleaned and lubricated, and does not depend on the mechanical load. Depending on use and cleaning, a chain can last only (e.g. in cross-country use, or all-weather use), for well-maintained derailleur chains, or more than for perfectly groomed high-quality chains, single-gear, or hub-gear chains with a full cover chain guard.
Nickel-plated chain also confers a measure of self-lubrication to its moving parts as nickel is a relatively non-galling metal.
Chain wear rates are highly variable. One way to measure wear is with a ruler or machinist's rule. Another is with a chain wear tool, which typically has a "tooth" of about the same size found on a sprocket. They are placed on a chain under light load, and if the tooth drops in all the way, the chain should be replaced.
Twenty half-links in a new chain measure , and replacement is recommended before the old chain measures (0.7% wear). A more conservative limit is when 24 half-links in the old chain measure (0.5% wear). If the chain has worn beyond this limit, the rear are also likely to wear, in extreme cases followed by the front chainrings. In this case, the 'skipping' mentioned above is liable to continue even after the chain is replaced, as the teeth of the sprockets will have become unevenly worn (in extreme cases, hook-shaped). Replacing worn sprocket cassettes and chainrings after missing the chain replacement window is much more expensive than simply replacing a worn chain.
While the exploded view diagram here shows the older type having full bushings, modern bicycle chain has "half bushings" formed into the inner side plates, referred to as "bushingless" and "bushless" by Sheldon Brown.
1976: Shimano briefly made their own 10 pitch Dura-Ace track-specific system with (approximately) pitch from about 1976 to 1980 May 6, 2013, progettopistavintage.blogspot.dk Quote: "... Somewhere in the 1970s, Shimano people got the great idea to reduce the chain pitch to 10 mm ... Somewhere in the 1980, the 10 mm pitch series were discontinued...."—called Shimano Dura-Ace 10 pitch. The Shimano 10 pitch system is incompatible with ANSI standard #40 (1/2″) e.g. chains, sprockets and so on, bikeforums.net: why Shimano stopped 10 mm small pitch chain Quote: "... 10 mm required new chain, new hubs, new sprockets, new chainrings, new chainwhips. Basically just about anything that touched the drivetrain was incompatible with 10-pitch with the exception of the spiders on your crank arms..."Shimano#Shimano products Quote: "... Metric chain—Shimano designed chains with a 10 mm pitch instead of the conventional half inch pitch...." and was outlawed by the Japan Keirin Association, helping in its demise.
With derailleur-equipped bicycles, the external width of the chain (measured at the connecting rivet) also matters, because chains must not be too wide for the cogset or the chain will rub on the next larger sprocket, and chains must not be too narrow, which allows them to fall between two sprockets.
Chains can also be identified by the number of rear sprockets they can support, anywhere from 3 to 13. The following list enables measuring a chain of unknown origin to determine its suitability.
The Wikibook, , has more details on this topic.
In the case of derailleur gears the chain is usually long enough so that it can be shifted onto the largest front chain ring and the largest rear sprocket without jamming, and not so long that, when shifted onto the smallest front chain ring and the smallest rear sprocket, the rear derailleur cannot take up all the slack. Meeting both these requirements is only possible if the rear derailleur is compatible with the gear range being used on the bike. It is broadly accepted as inadvisable to actually use the large/large and small/small gear combinations, a practice known as cross-chaining, due to chain stress and wear.
In the case of single-speed bicycles and , the chain length must match the distance between crank and rear hub and the sizes of the front chain ring and rear sprocket. These bikes usually have some mechanism for small adjustments such as horizontal dropouts, track ends, or an eccentric mechanism in the rear hub or the bottom bracket. In extreme cases, a chain half-link may be necessary.
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