Words, the only place aluminum bikes are considered dangerous is amongst a certain very vocal minority on the internet. Even low end mountain bikes can handle the abuse you are giving that bike. IDK who told you that bikes were built for sub 160 lbs, but with the possible exception of some very light road bikes, that is BS. On the other hand, if you like riding and a new bike will make you happier, than go out and do your part to jump start the economy.