No it isn't. I can't even reach my J1's power button when keeping the phone in one hand (and the leather casing folded behind the phone.) I mean, of course you can reach it if you move the phone in your hand. But that makes me feel uncomfortable when biking, as you don't have your fingers around the phone anymore.

Oh, and by saying one hand, I obviously mean my left hand. Because I always keep the phone in front left pocket of trousers.