An update from the Rat Patrol UK:

Many thanks for the info re swing bikes. The Knee Trembler works and sure is suitably named. The looks you get from the squares are so funny, as you suddenly go into sideways mode. For about ten seconds she felt like a real killer then became fairly normal. Then 1 minute later I fell off in front of a bus queue, but hey best do that kind of thing in public. At work I was called a genius by one guy and an idiot by the others, they just dont seem to understand. One comment was 'are you trying to be eccentric'. 'That is something that one does not need to try' was the crushing reply.

I was going to use a scrapper that I found in a hedge but the seat tube was fucked, so in a fit of inspiration I chopped my old Kona, aaaagh. My first decent bike hacked up by some low life chopping scum.Ha. But in hindsight it belonged my exmate Bob who ripped me off for some money ages ago so what turns around comes around (or something).

The only problems with The KneeTrembler is that it is easy to clip the front wheel with your feet but I am getting used to this. Construction is brazed using an old fork and head tube of the scrapper I found. I will get you better photos if the sun ever comes out again. A lovely bike to ride, many many thanks for the inspiration. What next?