How could photographer shoot himself? Mirror, or tripod and time delay set in camera would be the answer.
But how photographer could shoot himself while riding the bike? No mirror, nor tripod might be helpful in this case. But you could adjust your camera, set a friend of yours in the right place, hand her/him camera and precise instructions about what exactly she/he has to do and after that ride some dozens of laps around. As a result, you could have a few good photos. Thanks to friends for this, eee… friendlfie!