Just one advantage of push-bikes is their low running costs – I use mine almost every day, yet have spent only £40 on it over the last 3 years!
Here is the link to a very interesting book www.withouthotair.com.
Also, here is a link to a video of the author discussing the subject, which complements the book rather well: www.youtube.com/watch?v=GFosQtEqzSE.
And an interesting link to a site which allows you record your energy (gas and electricity) consumption and displays it in graphs as you accumulate values over time: http://readyourmeter.org.
I’ve just started using this to record my landlord’s household energy consumption. There are 6 of us in the house and we will try to reduce our consumption each week, in an effort to beat that of the previous week, thus steadily reducing costs. Quite a nice activity I hope might catch on here in Dorset! It is actually explained by the author of the book in the video link above at 36 min 45 seconds into the video.