All these threads about the fairy have finally got to me. On the way home tonight, about 7 miles into my 13 mile rural commute, rain coming down and dark, I started to feel a bumping sensation on the back wheel. I carried on home with strange handling at the back. Checking the tyre I found that it had a large hole, maybe 7 or 8mm diameter and the inner tube was pushing through creating a distorted bulge. Fortunately I had suffered from the fairy back in September and put some slime tape in the tyres, this had stopped the loss of air this time. Enough of the saga, now the question ... The bike is a Giant Cypress and has 700Cx38 tyres, do I have to stick to this size (the 38 bit) or can I use narrower a narrower tyre?