I have an original Sparton tube that I bought from Mike a number of years ago and have also been out in the "Shakey" version. I too have noticed that the "Shakey" does tend to make you slip out. On closer ispection the original version has the seat material wedges stiched in an opposite direction i.e wide portion at the back of the tube rather than at the front, to the "Shakey". Hence the tendancy to slip forward. Also the "Shakey" seems too take much longer and a damn sight harder to blow up, but the valves look the same. Anybody found the same?
