We had a longish discussion here a while ago about the problem I was having with my helmet wanting to rise at speed. I take the point that I probably needed one size smaller, although my odd-shaped scone probably means what I *really* need is a more expensive helmet with adjustable padding so I can use more on the sides and less fore-and-aft. But there remains the issue of the upward force. I assume it's due to the laminar flow of air over the top of the helmet, and surmise that if I could break up that flow by adding a small spoiler, it might at least reduce the problem. Googling 'helmet spoiler' throws up a few, so obviously it's something that can be done, but most of those are specific to models other than mine. Any ideas about whether it can be done and whether it's worthwhile? I assume you'd want something that glues on, because any drilling would weaken the shell. Any other caveats? The lid in question is an HJC CL-14 ('Sword' graphics, not that that's relevant).