I worked on it with a mate who normally re-upholsters armchairs and such like. We took the original cover off. I showed him what shape I wanted - we picked out the firmest lump of foam we could find in his shed and he cut it to shape with an electric carving knife. It's almost right - just a smidgeon low where it starts to kick up at the front. Trouble is you only get one go at it as pulling the staples isn't very kind to the original seat base.

He stitched an extra piece both sides ot the original cover then re-fitted it. He has got the lines spot on I think. I did over 170 miles of mixed going today - legal forestry tracks - one lane hill roads and a blast home on an 'A' road. No probs - I didn't have to think about my tender ass once. An added plus is the more relaxed knee bend makes it easier on my creaky old knees when I'm climbing up onto the pegs.

cheers - givit