Bicycle Rear Derailleur

A high percentage of the performance on the bike is determined by the physical preparation of the rider, but there is a significant part that is consequence of the rider's intelligence and ability when shifting gears. That's exactly what bicycle rear derailleur allow us to do. If used properly the gears can help us save a lot of energy.

Let's look a bit closer at how the bicycle rear derailleur work. A derailer leads the chain from one chainring or sprocket to another, while the chain is moving forward. The front derailer is a simple guide that moves the chain from side to side. The rear derailer is a bit more complicated, because it also contains the spring and pulleys that adjust the length of the chain as it moves to different-sized sprockets.The sprockets that are closer to the middle of the bike (small front, large rear) give the lower gears. The outer sprockets (large front, small rear) give higher gears. So depending on the gear you choose you'll have to push more or to spin more. In other words, no matter which discipline you choose, a proper use of the bicycle rear derailleur will mean a great energy saving for the rider.

Most levers are now located on the handlebar, though sometimes you can still find them on the frame of the bike, either ways the current models of gears are very efficient and quite sophisticated. The advantage of being located on the handlebar, is that it'¡s easy to reach them there, hence avoiding movements that could make the rider lose his balance.

In order to use them properly you have to “read” the road on which you are riding and foresee the changes of the gradients; flat, uphill or downhill. Generally we recommend to shift gears progressively and avoid the gears that make the chain cross over at an extreme angle. These "criss-cross" gears are bad for the chain and sprockets. Remember also that the front derailer shifts using the upper part of the chain, the part that transmits power to the rear wheel. As a result, the front shifting will not work so well while you are pedalling very hard, or slowly, or both. The rear derailer can usually shift under full load, but it is better for the chain to ease up a bit during the shift. Then again, each rider has its own tastes and training goals, some will rather spin, others prefer to push and others look to keep the perfect cadence.