I also posted my earlier item about the cardboard bike on the cycle forum at YACF. It has received a number of amusing, quick quips, so if you have a sense of humour and need a little chuckle have a look at http://yacf.co.uk/forum/index.php?topic=65176.0 from comment No 4 onwards.
Additionally, posting number 13 shows a video of the cardboard bike being ridden, on road, by the designer. So it is not a joke, but a very practical and innovative use of cardboard. Just check out the video below: