Heavy Bikes are better !
Unless you are a professional or amateur racer..... Ride as heavy a bike as you can ! You will get a better workout, You will save money as they are cheaper and more rugged requiring less repair, and your crashes will occur at slower speeds. You go out and ride for two hours and come home. Do you really care if you went 30 instead of 40 miles ? The idea was to burn 2500 calories either way.. In addition, everyone who passes you will respect you more than they would if you could blast past them on a whim. All the bike manufacturers spend millions of dollars to brainwash you into thinking you aint cool if you dont have the latest lightest bleeding edge technology. Are you going to let yourself fall victim to that ? Me personally- I like to ride my sixty pound tandem solo. It rides much like a limousine and has many other benefits. Twice I have been able to given broken down motorists a ride back to town.