A motorcycle's half helmet should fit snugly and securely to provide adequate protection and comfort. Here are some guidelines on how a half helmet should fit:
Head circumference: Measure the circumference of your head using a flexible measuring tape. Take the measurement just above your eyebrows and around the widest part of your head. Refer to the helmet manufacturer's sizing chart to determine the appropriate size based on your head circumference.
Snug fit: The helmet should fit snugly on your head without being overly tight or causing discomfort. It should not have any significant gaps or spaces between the helmet and your head. A properly fitting helmet should provide even pressure all around your head.
Stability: The helmet should sit level on your head and not tilt forward or backward. It should remain stable and not shift or move around when you shake or nod your head. The chin strap should be securely fastened and keep the helmet in place.
Cheek pads: The cheek pads inside the helmet should fit closely against your cheeks without pressing too tightly. They should provide a secure and comfortable fit, ensuring that the helmet stays in position.
Proper visibility: Make sure the helmet does not obstruct your vision. The front opening of the half helmet should not come down too low or obstruct your line of sight. You should have a clear view of the road and surroundings without any hindrance from the helmet.
Chin strap: Adjust the chin strap so that it is snug and comfortably tight under your chin. It should not be overly loose or too tight to cause discomfort or irritation. Fasten the chin strap securely and ensure it stays in place.
Test the fit: Once you have the helmet on, try moving your head in different directions—up and down, side to side—to check if the helmet stays in position and does not slide or shift. Also, check if the helmet feels stable and secure during these movements.
Remember, a properly fitting half helmet is crucial for its effectiveness in protecting your head. If you are unsure about the fit or have any concerns, it's recommended to consult with a knowledgeable helmet retailer or refer to the manufacturer's guidelines for more specific information about their particular helmet model.