A helmet can save your life if it is fastened correctly. Heed the correct size and secure fastening when selecting a helmet. Watch the following instruction video: how to fasten the helmet properly. Below the video you will find a brief guide.
Let's adjust the IAS system until it's fully loosen. Use the rotary dial wheel and height adjustment. The helmet will pass through your head more easily.
Put on the helmet. Adjust the rotary dial of IAS system first around the perimeter of the head so that the helmet holds firmly and comfortable on the head.
If necessary, set the IAS even at height by pushing it with your thumbs against your fingers holding the helmet. Go step-by-step, until you find the optimum position, so it remains just below the curve on the top of the head. You can use the mirror to check it.
Set the Y dividers (FAS strap) position so they connect right under the earlobe and lie close to your head. Make sure that the front and the back strapshave equal tension. Open the clasp with your index finger and change the level or position of straps. It's important to set horizontal position because of load distribution. The right and the left sides should be equal.
After closing the monomatic button on the chin strap, the strap should still have a bit of space. If it isn't that case, take off the helmet, undo the sleeve, take the webbing strap from the third safety strap. Adjust it's length. When you got the right length, try the helmet on, and if everything is right, threat the strap back through into the third loop and put on the sleeve.
A properly set bicycle helmet does not slip and does not move as the head moves.