From what I know, the term Riders is mostly used to refer to Motorcycle riders.
I have a rider friend and he is really into motorcycles. I think we were in high school when he owned his very first motorcycle. He customizes the paint and keeps on upgrading parts. Before he left for KSA, I think he had about two or three motor bikes. No one will use them when he leaves so even if it is against his will, he sold them.
He is still into this and I think he will certainly appreciate Arai Helmets as a gift for his upcoming birthday. Shout out to his girlfriend! :p