I had an interesting discussion with an experienced roadie a while back. I am riding a hybridized chro-mo Giant Yukon that weighs in at about 30 pounds and puts me in a moderately upright position. I'm working on losing weight and becoming a better rider and was discussing the possibility of moving to an aluminum framed, fiber forked road bike.
His take was that I was better off sticking with what I was riding for now as the weight and geometery would force me to work hard enhancing weight loss and gains in strength and endurance.
"If you can put in a respectable ride on that thing," (paraphrased quote) he said, "when you get on a good road bike, you'll fly." He compared it to a baseball player swinging a weighted bat or a sprinter pulling a parachute.
I thought it was an interesting concept, so I thought I'd bring it up here. Could there be a benefit to riding a heavier "training" bike part of the time? Could it be another means of adding work load, like riding into the wind or uphill?