Hub gears may seem unusual in a world dominated by derailleur gears, but it is actually a very efficient system with a number of unique benefits. Unlike derailleurs (where the gear sprockets are exposed), all the mechanisms of hub gears are enclosed in a weather-resistant alloy shell, ensuring consistent reliability in all conditions. This also means that the gearing is not affected by the mud and grime thrown up from the road, which in turn means less maintenance is required than with an external derailleur system that can get clogged up over time. In addition, one little-known benefit of hub gears is the ability to change gear without pedalling. For instance, you can change into a lower gear whilst sat at a red light, without worrying about damaging the gears or having your chain come off.