[yummyfajitas]

I'd strongly suggest not letting the fear of possible harassment deter you. Wait until it actually happens. Worst case, you complain to the front desk and homeboy gets out of his yearly contract 11 months early. (They usually have cameras everywhere, so it wouldn't even be a "he said, she said" issue.)

Most of the very large men have no need to harass random women - all they usually need to do is walk into a bar and say "hello". And I've never met a guy at the gym who would even be tolerant of such harassment, let alone participate.

tl;dr Fitness is too important to let a one-in-a-million bad event deter you. Statistically speaking, your biggest worries are poor fitness > harming yourself due to poor form/bad luck > getting harassed at the gym.