I think this was against the rules back in the days I did sailing regattas.

If someone currently employed by Zipp is reading this: more of this type of stuff please, for the current products. Zipp's current publicly available technical detail is atrocious.

BMC tri bikes of the 2012 era have an aerodynamic "tripwire" on all the leading edges of the frame and fork. I can't speak for the very latest models because I haven't looked at one up close since I sold mine.

The tripwire is basically an elongated dimple. Dimples are good when the object is spinning and you don't know where the leading edge will be, like a golf ball or wheel rim. Since you always know where the leading edge of a bike frame and fork is, you put in a tripwire instead.

The helmet with all the dimples on it is kind of silly, since you spend 95% of your time looking forward. A tripwire line would be a lot smarter.

A tripwire only works properly at one angle of attack. Which is unlikely to be the case for a helmet, especially one used by lots of different people.

Lazer did exactly that with the Wasp. For some people that was a very, very, very fast helmet. For others it wasn't so great. The reason the poster prior to me posits is the reason why.

I posted this elsewhere but, from all of my reading, it seems to come down to the height of the imperfections on the surface relative to the boundary layer. If the height of the imperfections is less than the height of the boundary layer, there will be no effect.