You are suffering from hormonal changes causing Androgenetic alopecia causing hair fall. It's completely stoppable even regrowth of hair is possible with certain medications without any side effects. Treatment depends on the grade of hair loss. So, it's a must for diagnosing which grade, you are in for an effective treatment. Please  send photos of your head, by direct online consultation for accurate diagnosis and proper treatment.

As said correctly above.... various factors can lead to hair fall....need a proper investigation n images for the best management. U can consult me online for the same.

Bike and helmet has nothing to do with hairloss. You are suffering from androgenic alopecia which is also called as pattern baldness. The hairs start reducing in density at the crown (top) and also the hairline starts receeding  from the front. This is usually progressive throughout life unless treated. It is usually accompanied by severe dandruff which we call seborrhoea. The FDA approved treatment for this condition is the best. No oil or cream will magically work because the hairs are getting miniaturised  and eventually disappearing due to the hormonal effects of DHT on the hair roots. Please contact me with photos using online consult option for proper examination and treatment.

Hello! Is your friend losing hair mostly in the front,top and the highest point(vertex) of his head? If so, he may have what s called Androgenetic alopecia, or male pattern baldness, the commonest cause of baldness in men. He needs immediate medical attention to arrest further hairfall and to help regain lost hair. He will also need a blood work up to figure out if there are any contributing nutritional factors to his hair loss