Mmmm interesting as I would say without measuring, probably closer to 300mm.

Looking at my spinny last night it would seem very very flat along that leading edge for about the first 100mm or so, not a good looking leading edge at all. As soon as you release the sheet to the point the luff collapses, that whole 100mm and next 100mm in the middle section folds. How much change in shape can you get by tightening the luff tightening lines ?, surely just raising or lowering spinny pole will do the same.