I'm gonna hit Mt. Diablo on Sunday and see how it goes. They will usually be much more interesting, and tough spots that you walk should generate goals for your next ride there. If you read the deal on what to look for on a used bike, you'll see that Shimano offers different gruppo's or levels of equipment for drivetrains, hubs, brakes and shifters. Believe me, there's a difference in quality, the better stuff is smoother, nicer feeling, quieter and longer lasting. It will also take the heavy abuse and perform better, making your ride a joy instead of a crappy experience.
Cheap bikes suck.
Yeah, they've all got two wheels, but all cars have four wheels and there's a tremendous difference between a Chevy Cavelier and a Corvette. Take your time and be patient. Don't run out and buy a bike you'll regret later on. Go to a shop that's friendly and ask plenty of questions. Do what your doing right now, research it, read about it and ask and many of us will be happy to help out.