Pretty sure it's a cog with more teeth. As I recall, the eccentric BB would accommodate enough adjustment to permit the use of two different sized cogs. I do agree, it's a little gimmicky, but still. Ain't she perdy?
http://www.englishcycles.com/custombikes/black-rainbow-divide-ride/
Internally geared rear hub. The front wheel is set up that way in case the rear internally geared hub fails somehow and get you home as a single speed by swapping wheels. I'm not familiar with that hub and how it could fail. Neat idea though.
In that capacity, the Hypersmock 2 is great. Given that it sees the inside of my pack more than a good rain storm, I like that it is as light as it it.Thanks. I could probably go a bit heavier to add durability. Need a rain cover to live in the pack for the rare summer or winter storm that can come suddenly here in the southwest. Most of the time I'll simply plan around weather.
check that article out, that bike even breaks down to ship w/removable rear chainstays, etc. Purpose built for traveling from the UK to the US. Nice stuff.