It's the disc wheel on the Extrawheel that baffles me.
Fast bike + Extrawheel makes a lot of sense if you want to ride somewhere, camp and have a fast bike to do fast bikey things with. Seems a bit gratuitous for that to have a disc, thobut. Of course, there's logic for having a rear wheel in the Extrawheel which can be easily swapped with the bike, in order to have a wider range cassette for towing. In which case a normal wheel in the bike and a disc in the trailer would make sense. I reckon it's all about the bling.
