Finger Mountain Bike

ussually pointer or middle finger, I think just use my pointer, honestly theres no correct answer how to do that is just what ever feels comfortable for you. ussually used less fingers allow you to apply a wider range of braking, usually when people have more fingers on the brakes, they tend to apply more pressure on the brake and may tend to brake more, so ussually stick his middle finger and pointer, but what ever feels good and works for you.

fingers under on the brakes you have more fingers on the handlebars which gives you more grip and control of the bike.

Cheers:)

your pointer finger and the Middle