With the Tour de France wheeling its way through France and the Commonwealth Games about to start, we're wondering: why do cyclists wear those cray helmets?
Here's the deal:
Why are they shaped like sideways tear drops?
The smoother and rounder the design, the less air resistance they create = they help cyclists go faster. When cyclists put their heads down to race, the tail tucks against their back. Sleek and speedy!

Why are they spongey on the inside (sweaty - ew)?
The spongey stuff is for safety. It's basically a high tech shock absorber. There are safety standards that helmet makers have to reach before their helmet is approved, and high quality sponge is part of that.

Which helmet is the fastest?
Lazersport reckon their Wasp helmet (in the pic above) is the quickest. From the shape, to the inbuilt sunnies (totes not the technical term) and more, this helmet really minimises wind resistance. You even have to put the helmet on in two parts.
You're looking at spending a few hundred bucks to get your hands on one of these guys, and looking like an uber cyclist in front of your mates means you better be able to back it up with some speedy work!

What are they made of?
The spongey inside is a high performance polystyrene (like the white throwaway cups you sometimes see) and the hard outside shell is a material called polycarbonate. It's super light and thin, but heaps strong.

Did you know..?
Elite super cyclists' helmets sometimes have as many as 21 air vents. Helps 'em keep a cool head. Literally.