I would agree with you that it does take a very lean "larger" athlete to achieve 4.0w/kg, but the smaller guys can usually get there fairly easily with some consistant dedicated training. Im 6'2" and ~170 so I am really happy when I reach 4.2-4.3. Mostly this is because I am that light, which means I'll climb better and run better. There are a lot of kids who just get a little training in and they are at 5.0w/kg because they weigh 135lbs.
But I feel the most important thing is aerodynamics (W/CdA) for bike performance in triathlon. I have rolled a 53:xx 40k at 300w on an aluminum bike with tufos for tires (if I only would have run vittorias). I don't understand why guys focus so much w/kg in triathlon. Most tris have limited climbing on the bike anyway. The most that I have had is 1500' and I was still right about an hour.
Seth Wilkie DPT, ACSM-HFS
But I feel the most important thing is aerodynamics (W/CdA) for bike performance in triathlon. I have rolled a 53:xx 40k at 300w on an aluminum bike with tufos for tires (if I only would have run vittorias). I don't understand why guys focus so much w/kg in triathlon. Most tris have limited climbing on the bike anyway. The most that I have had is 1500' and I was still right about an hour.
Seth Wilkie DPT, ACSM-HFS