Why use internal gear hub

[SkipdiverJohn]

I am a great fan of derailleurs but from an engineering point of view they have their shortcomings. No engineer likes a traction system where the elements run out of alignment and , obviously, the derailleur depends on misalignment in order to function.

From an engineering perspective, derailleurs are absolute shite! And the more cogs you try to cram on the back wheel, and the shorter the chainstays you run for quicker handling, the more shite they get. That's before you start to consider unwelcome knock-on effects like weakening the rear wheel due to all the dishing and running with huge variations in spoke tensions. Their only saving grace is they are the cheapest way of getting the widest possible spread of gears. A reliable functional hub gear, by it's very nature, has to be a fairly decent bit of engineering, which imposes a price floor on what you can build them for. On the other hand, low end derailleurs are essentially just stamped out of pieces of sheet steel., which means at a mass production level the individual bits cost pennies to make.