The situation is as follows: You're sitting in the saddle and in front of you is an impressive climb which has no end in sight. A quick tap to the left control shifting the gears to the smallest chainring effortlessly. Grabbing the hoods to find the perfect position and so begins the climb. Easy to say, its no problem to get the derailleur to shift in the perfect condition when well adjusted. It is a component of the drive-train that requires little attention and who works without being noticed, except when its shifting becomes inaccurate and noisy. Shimano with its wide range of products covering practically all the possible variants of components existing, which could be mounted on almost all road and MTB bikes.