Can you make the helmet bigger?

If you CANNOT wear the helmet at all, sorry I cannot help. However if you CAN WEAR BUT CANNOT CLOSE the helmet’s back side, I can extend it Free of Charge, as long as you are willing to send it back to us at your own expense. Our standard helmet size is around 62-63cm. To measure, from your left to right ear in circumference and across your nose. The helmet is designed for NORMAL PROPORTIONED ADULT head.