G-Boxx Derailleur based drives achieve their full efficiency of about 98,5 % only under new and clean conditions. Dirt and mud causes a large increase in frictional resistance which rapidly leads to a loss of efficiency. The exposure of all drive and shifting components on a derailleur based drive has a negative effect on the system's function. Conventional chain drives require a lot of mainte- nance effort, they run a high risk of damage and they are subject to a high abrasion. For different gears the chain has to be set to a different length by a chain tensioner. The only way to prevent the chain from falling off when the going gets rough is to pass give up on two front chainrings and mount a chain guide instead. Considering these factors it quickly becomes apparent why this sort of drive is not the best solution for off road cycling. The G-Boxx concept eliminates the disadvantages of a derailleur based drive. It needs little (almost no) maintenance. Efficiency is maintained at a constant level between 96% and 98%. Due to its enclosed design the gears and the primary drive are protected from dirt, collisions and breakages. A G-Boxx integrated into the front frame, like the Nucleon TFR or TST design, with the swing arm pivoting around the force-emitting chain ring, gives the following advantages: The centre of gra- vity is low and central to the frame, which gives a bike excellent handling characteristics. The unsprung mass at the rear is reduced (because derailleur, sprocket and freewheel are not nee- ded) and the drivability and the suspension performance improves. A lighter and stiffer rear wheel design is possible. The Nucleon G-Boxx design allows a constant chain length so no chain ten- sioner or chain guide are required. The chain is tensioned using sliding dropouts, similar to the system used on single speed frames. A thrown chain is no longer possible. Another big advantage: the planetary gears inside the G- Boxx allows shifting actions in any riding situation with or without pedalling, moving or stationary and even while slamming on the brakes. The advantages of a gear box drive are best shown if the rear hub design is changed as well. For that reason we designed a special rear hub for the Nucleon series called the COR (Compound Rearhub). Due to the wide spacing of the COR spoke flanges the rear wheel becomes stiffer and stronger than conventional wheels. By separating the Hub into three sections the assembly and disassembly is easy, fast and clean because drive and brake remain in position, and don't need any kind of readjustment or realignment. Since its release in 2004 the G-Boxx concept has been subject to a continuous improvement pro- cess. There are two key components to G-Booxx - the ROHLOFF® 14 ratio planetary gear unit and the G-Boxx shell which allows it to be integrated into the bicycle main frame. The main difference between this and former gearbox concepts is that with the current G-Boxx design the gearbox shell is welded into the front frame. The shell is called G-Boxx because the planetary gearing, is already enclosed by a casing. The gearing, placed directly above the bottom bracket shell, is powered by the primary drive on the right side. This is composed of the cranks, the bottom bracket unit, a chain ring mounted to the crank spider and a chain ring attached to the gearing. The G-Boxx casing protects the primary drive and the gear itself from dirt and damage. The secondary drive, powering the rear wheel, is a free running chain on the left side, leading from the output side of the gearing to the rear wheel chain ring. All shifting processes occur inside the encapsulated G-Boxx. The shifting operations are controlled by a rotary shifter mounted on the handle bar. Changing or adjusting of the cables is simplified by a cable box beneath the down tube.