External and Internal Bicycles Hybrid Gear

Do they have bike shops over there, Mate? <Splutter>

Unfortunately right now, there is not a commercially made method that has combined the two types of drive units. The reason ( I presume) is that they are aimed at different types of cyclists and cycling terrain. The internally geared hub has a wide hub shell to hold the three/five/seven/eight or fourteen speed gear clusters this only leaves about 15-17mm of space to attach and hold an external gear (driven off of the hubs' internal gear through a pawl shaped like a V with a thick base)). Conversely, the 7/8/9/10/11 speed external gearset ( cyclists call them 'cassettes') takes up the same amount of room and then some, leaving a big 2-4mm of space between the last rotating gear and the frame but uses a narrower hub shell and a different method to drive the cassette ( a series of rounded or squared off splines contact the freehub body ( The freehub body is bolted to the hub shell and the cassette threads onto it.)). The freehub body also has pawls but the are much smaller and located on the outside of the freehub body, they "catch" the hub shell when you pedal and drive you forward. HOWEVER: This does not mean that you can't change the front drive sprockets! This will net you a much larger gear change if you move down to a 22/32/42 gear tooth combination.... but this is a slightly more expensive route to take and may come with some other problems.....

Thank you very much for your comprehensive explaination!

have a look at SRAM dual drive