What they all said. Get a decent bike, learn how to fix a flat, tell your boyfriend to shut it - and lose 20 lbs if you want to. I won't lie and tell you it won't improve your cycling, if you have the lbs to lose. But buying a lighter bike will give you a proper kickstart, and probably the will to ride faster. Older bikes are not inherently more solid than new bikes. All bikes have parts that wear out and need replacing from time to time, that's just the way it is.