You guys need to stop bickering. You are both right. After all, a fast twitch muscle fiber is bigger than a slow twitch one of the same type. That's why FT dominate type bodies in general are more muscular and heavier than ST dominate endurance types.

As far as Lance goes, who knew the "onions" are not very important for top level cycling? Think about the "onion" he lost and it's function. That is one reason the beef industry performs the same operation in cattle. Turning a bull into a steer will decrease muscle growth and density.

On as side note, again both of you are right. The added muscle as long as it's FT is very helpful in the flats. But not on the climbs. I am the polar opposite of the OP. I am a stocky mesomorph loaded with FT muscles. 5'8" 200lbs(trying to get back to 185) and not a lot of fat. As long as it is flat I can roll in the high gears at a high cadence all day long because I have the power and can transfer some of the load to the cardio system. But...... put me on any kind of incline where I am forced to carry that "load" upward (at a slow cadence no less) and I become a turtle and tire out quickly! Again, that's why sprinters sprint instead of running the 10,000 meters. Their bodies aren't made for it.

In my other fitness endeavors, I find that for me 175-180 is the ideal performance weight. Below that and I start start seeing performance losses because of decreasing strength issues. Above that and the performance starts to slip because of speed, quickness starts to go down.