Various Derailleur Styles
From GICLWiki
Contents |
Introduction
The rear derailleur has two main purposes: 1.) to keep tension in the chain, and 2.) to shift gears. Since the 1890's (when the derailleur was first patented/invented), several versions of the derailleur have been sold on the market. However, with each new patent, derailleurs have seen some very drastic changes and also some very subtle changes. Four major Styles are covered below: 1.) The Whippet Two-Speed Derailleur, 2.) The Cambio Corsa, 3.) The Gran Sport Derailleur, and 4.) The Modern-Day Derailleur. These designs are meant to be representative of the vast number of changes that derailleurs have seen through the years--from beginning to end.
1899--The Whippet Two-Speed Derailleur (or New Protean)
http://www.users.globalnet.co.uk/~hadland/old_derail.htm
This design was invented in 1899, and in that same year, Charles Montague Linely patented it under patent number 18,240. It works by a lever that the rider controls in order to switch the chain from sprocket to sprocket. On this design there are only two gears, and the pulley at the bottom of the chain takes up any slack the chain may have in either gear. At this early stage, it was quite a luxurious mechanism for the rider. An article in the December 1899 issue of the CTC Gazette described its operation as, "without the slightest jerk or sound." This was a major achievement in the cycling world since many inventors had struggled with a multiple sprocket approach on earlier bicycles, and it really helped to lead into later designs.
1940--The Cambio Corsa
http://www.campyonly.com/history/timeline.html
On, May 4, 1940, this rear derailleur was patented by Tullio Campagnolo. The following August, it was introduced into the market. Each piece of this rear derailleur had to be handmade, which required a great amount of labor and time.
The Cambio Corsa kept the lever idea of the Whippet Two-Speed Derailleur, but it was much more sophisticated and practical for the rider. It used a system of seatstay-mounted control rods that the rider used to loosen the rear quick release and allow shifting. The rider had to completely stop pedaling and move the chain back and forth with a "fork" device, which sat around the chain on top of the chainstay. The rider was also required to backpedal in order to shift the gears, and the wheel moved back and forth to take up slack in the chain. After completing the shift and securing the wheel, the rider was finally able to continue pedaling. Of course, this was very tedious and inconvenient.
The development of this derailleur was short-lived, as Campagnolo soon after invented the Paris Roubaix, which shifted in the same manner as the Cambio Corsa but with only one lever to shift instead of multiple levers. Obviously, ths Paris Roubaix was easier to use than the Cambio Corsa, which inevitably halted the Cambio Corsa's production. Still, the Cambio Corsa was a milestone in rear derailleur history as the first sophisticated rod-shifter, and it also helped to inspire later designs.
1951--The Gran Sport Derailleur
http://patentpending.blogs.com/photos/uncategorized/campag_2.jpg http://www.campyonly.com/history.html
Campagnolo continued his modifications to the derailleur and introduced/patented yet another derailleur--the Gran Sport Derailleur--in 1951.
It was a single cable, parallelogram derailleur made of chromed bronze and paired with bar-end shift levers (which were first made of chromed bronze and later made of aluminum). This derailleur, like the Cambio Corsa, used a sliding rod to shift the bicycle gears. However, unlike the Cambio Corsa, the rider did not have to completely halt pedaling in order to shift gears because gear-shifting was done through the use of cables (much like modern derailleurs). The streamlined design of the Gran Sport derailleur is one that lasted over 30 years and served as a very close model for modern-day derailleurs.
The Modern-Day Derailleur
http://www.nexternal.com/icycles/images/rd-force.jpg http://www.icyclesusa.com/catalog/sram/sram-force-10-speed-rear-derailleur.htm
This Modern-Day Derailleur is an excellent model of all of the advances that derailleurs have gone through. Modern-Day Derailleurs took the cable design of the Gran Sport Derailleur to a whole new level by allowing complete control through movement of a lever on the handlebars that signals the rider's wants to the derailleur. Some derailleurs feature carbon fiber housing parts which reduce weight and increase strength. Due to such advanced materials being used, some of the modern derailleurs weigh as few as 180 grams. They have a wide range of shiftability and can be used on systems which feature multiple rear cogs. Other features include the ability to be used on lower speed systems as well and precise (3mm) adjustability.
One major change that can be seen in the Modern-Day Derailleur as opposed to the earlier versions is that modern advancements concentrate on criteria like aesthetics and top-performance as opposed to simply the working mechanisms themselves. Previous advancements were still perfecting the mechanics of derailleurs, but today we concentrate on the finer details when trying to improve the design of the derailleur.
Conclusion
Clearly, bicycles have come a long way--from a two speed bulky mechanism that needed to be rider operated to a nearly effortless, light, and strong mechanism that is also aesthetically pleasing. While each derailleur above serves its purpose, use becomes easier with each changing model and one can easily see the evolution: each sequential version has bits and pieces of the earlier versions, but each also brings its own new features and ideas.
