I have a LG Rocket and have been experimenting with its positioning, both where it sits on my head and how I hold my head. I notice that if I wear the helmet so it is touching my back, the wind noise is noticeably louder compared to if I look down a bit more. In the latter position, I don’t feel the helmet on my back and I know it is not flush as it is in the first position. However, I hear almost no wind noise when I look just in front of my wheel with my head looking down. I am as low in the front as my aerobars will let me go, if that matters.
**So my question: ** Is wind noise an accurate indicator of drag, thereby meaning I should wear the helmet in the position that is the quietest, regardless of whether the helmet is flush with my back and shoulders? Or are these helmets made to be worn flush, regardless of the wind noise.
Not sure if this makes any difference, but in addition to less noise my rocket runs parrallel to my back when not touching my back. When I force it to touch my back the helmet is pointed downward and doesn’t look like it would be as aero. I have no idea if this would actually make it more aero or not, but I’ve determined that I will wear it not touching my back.
I was listening to a podcast recently that featured an MIT student doing research on time trial gear in a windtunnel, and he said that he found that one’s drag is actually slightly lower when you look down because it gets the air up off your back, but either way he said that it didn’t make much of a difference.
That is a good question and I notice the same thing. I think one of the MIT students posts here and could add some insight? Probably doesn’t matter a ton, but if that were the case, we wouldn’t be wearing the stupid looking thing in the first place, right?
I was listening to a podcast recently that featured an MIT student doing research on time trial gear in a windtunnel, and he said that he found that one’s drag is actually slightly lower when you look down because it gets the air up off your back, but either way he said that it didn’t make much of a difference.
Which podcast?
I remember doing a very basic experiment in biology where we ran a film of water down a flat, inclined surface in which was placed a solid in the shape of a wing. At the top of the plate were crystals of Potassium Permanganate which gave off solid parallel lines in the direction of the water flow which broke up after the wing shape demonstrating the turbulence. However when a small bump was added to the solid from (i.e. just above the upper surface of the wing) the disturbance was much less and the solid lines reformed much quicker. Basically this was showing the value of the "sternum??? bone) on a birds wing.
I think this may be along the lines of what you are expereincing. The back top of the helmet protruding a tad may be reducing the drag.
However this was a long time ago. I’m lucky I can still spell Potassium
It really does depend on your body position / type. Like do you have a flat back, or does your back “lump”. Is your back parallel to the ground? How big is your head?
All the different aero helmets really do perform differently on different people, in different positions, and it’s hard to make a generalization. Having less noise is probably a good idea, as noise is normally evidence of turbulent flow.
I cannot say for sure how aero helmets work, but I’m guessing they work by making your head a more streamlined object, as opposed to a head with a normal helmet, or a bare head (there are a couple of tests that have shown that having an aero helmet is actually better than not wearing one at all). Your back might just help by preventing air from coming into the cavity at your helmet tail; if that area was sealed, I’m postulating (although we haven’t actually tested this yet) that having the helmet flush against your back might not make a difference.
Also, you’re definitely faster wearing an aero helmet, even if it’s the worst, and even if it’s in a bad position. We actually tried putting a helmet on backwards (made you look like a unicorn), and that position wasn’t any slower than the conventional position. Not that we’d advocate it of course… (=
