If the fun we had aboard Piaggio's MP3 is any indication, motorcycles with more than two wheels have a big future ahead of them. The additional stability and traction you get from a tilting three-wheeler is quite an eye-opener, and they're still exceptionally fun to ride. If you want to take the concept one step further, though, an extra wheel at the back as well can actually make the entire bike narrower while delivering the sort of stability that can let you safely powerslide and drift all four wheels on an oily skidpan. Remember Yamaha's wild and wonderful Tesseract concept from 2007? The company is keen to get one into production, but as it turns out, Yamaha has run into trouble with patents held by an ex-courier and motorcycle safety advocate from the UK who has been working on a road-ready tilting 4-wheeler for more than 20 years.