1. Measurement
Measuring the head is a starting point for the entire sizing procedure. The circumference of the head should be measured at a point approximately two centimetres above the eyebrows in front and at a point in the back of the head that results in the largest possible measurement. Take several measurements to make sure you have the largest one.
2. Try On
Once you have determined your preliminary tape measurement, select the helmet that is closest to the tape measurement and try on the helmet. If it is between sizes, round up to the next largest one.
The correct procedure to put on the helmet:
If the helmet slides down on the head with no resistance, you have your first indication that it may be too large. If it will not slide down over the head at all it is too small. Many people unfamiliar with helmets are reluctant to pull down if they meet resistance as the helmet goes on, however if it is just snug going on, we recommend to get the helmet on. Only if the helmet is impossible to put on should you move up to the next size, as helmets that go on snug generally fit very well once all the way on. It is a fact that most people will select a helmet that is too large for them.
3. Horizontal and Vertical Movement Check
Once you are wearing the helmet, you should look carefully at the way it fits. Check to see if the cheek pads are in contact with the cheeks. Is there excess pressure on the cheeks? Look for gaps between the temples and the brow pad. Check the back of the helmet where the neck roll (if the helmet has one) makes contact with the neck. Does it touch at all? Or is it pushing the helmet away at the rear causing it to roll down over the eyes in front. After you have made your visual check, grab the helmet in your hands - one on either side - and while holding your head steady try to rotate the helmet from side to side. Note any movement of the skin while doing this, as well as the amount of resistance to movement. Next, check movement up and down, again noting skin movement and resistance. If in either test there was little or no skin movement, and/or the helmet moved very easily, the helmet is too large. A properly fitted helmet will cause the skin to move as the helmet moves. And, it will feel to the wearer as if evenly distributed pressure is being continuously exerted around the head.
NOTE: Helmets are a little like shoes, in that they do break-in a little. For this reason the best attitude to have when fitting is that the helmet should be as snug as you can stand to wear it.
4. Retention Check
This test may be a little uncomfortable, but it is very important to check. Fasten the chin strap tightly, hold your head steady, and grab the rear bottom edge with your fingers. Then try to roll the helmet off your head. If it comes off, it is undoubtedly too large. WARNING: Do not buy a helmet that can be rolled off the head with the strap fastened.
5. Pressure Point Check
Finally, unfasten the chin strap and remove the helmet. Immediately after the helmet has been removed, observe coloration of the skin of the forehead and cheeks. A reddening of the skin in a small area may indicate a pressure point. Pressure points sometimes are not noticed by the wearer for several minutes, or even hours later. They sometimes cause headaches, and are at the least, uncomfortable. If you notice a pressure point, but cannot remember experiencing discomfort there while wearing the helmet, put the helmet back on for a few minutes, paying particular attention to the anticipated pressure point. If you experience pressure point discomfort either time, go to the next larger size, repeating steps four and five.