Why is it s-l-o-w?

In 1900, when my grandma was born ino a affluent household in Melbourne, Australia,  electricity was new-fangled,  and there were no cars or radio let alone aeroplanes, satellites and computers. Then technology developed at an increasing pace. During the Second World War, the pace was astounding. German engineers developed the V1 and V2 rockets in only a few years, the British made big advances in radar and cryptography and the Americans developed the atomic bomb. Technology is accelerating on a spike, we are told. But some innovations seem to take forever...

The bicycle derailleur – 80 years too late

By comparison, it took about 80 years to develop and optimise the rear derailleur on a bicycle, an apparently simple parallelogram mechanism with five hinges and three springs. The tortuous history (of good ideas, missed ideas, buyer prejudice, and many commercial failures) is covered in huge detail in The Dancing Chain (Berto, 2005).The last major innovation was the invention of the slant-parallelogram by Suntour in 1964. This makes the jockey-wheel move downward as well as inward, so it follows the profile of the freewheel more closely, giving a smoother, quieter gear-shift.

Typical derailleur - the body has 5 hinges and 3 springs