This is an awesome post. I'm 15, 5'11 and weigh 295 as well. I LOVE riding bikes and I'm quite good at it too. You should definitely save up an extra $50 and go to a site called danscomp. It's a huge online bike shop. I recommend you get something with a 20.75-21inch top tube and 9inch rise bars. Make sure all the wheel bearings are sealed as well. I was depressed for a little bit but riding bikes really helps ALOT. Every one of danscomps bikes comes with free shipping so buy something that's on sale for 350 but costs more than that. It would be a great way to start out. A lot of good trustworthy brands are Fitbikeco, Kink, Cult, Odyssey, Sunday. It just depends. Hope this helps man. Just remember to keep your head up and do what you enjoy! and hope its help you