One ride a week is WAY too little, you won't build much endurance or anything else with that. Yes, you need a lighter bike, but you need to train. You're "kill yourself" idea is basically on the right track, you'll need to do some intervals, but you probably need to build a base of steady moderate-effort several-days-a-week riding first.

I found this book helpful:
http://www.amazon.com/Lance-Armstron...6841071&sr=8-1

If you can, get a heart rate monitor, if not, just use Perceived Exertion, start with the beginner-level training program - you're going to ride about 5-6 days a week - and follow the plan. You'll see improvement.