This isn't really all that unusual, people having sex with bicycles. The more you ride one, the more bicycle you start to become. I have an uncle who has ridden one every day, four hours a day, for the last 25 years. He's now one-quarter bicycle. It happens because your atoms mix with the bike's atoms. Consequently, the bicycle ends up becoming part human, too. One would expect this kind of activity from a person who is part bicycle. If he was having sex with his own bicycle, it's actually much closer to masturbation than sex, since basically the part you're having sex with is yourself.
We must also consider the possibility that the bicycle was having sex with the man, not the other way around. If so, the man might consider criminal charges against the bike (assault, rape, etc). It may be difficult, however, to convince a jury of assault charges against yourself.