Originally Posted by makeinu
When you wheelie all the weight is on the rear wheel. The geometry of the bike obviously doesn't change (unless you're riding a transformer). You also can't wheelie without driving the wheels. Therefore, the weight distribution must depend on the drive train.
Right you weight is over the rear wheel during a sustained wheelie. However, geometry determines weight distribution(in relation to the bike) which determines how far you have to tip the bike back to achieve this and that determines how hard it is to wheelie.(assuming gearing and suspension are kept constant). The drive train may actually affect how hard it is to maintain the wheelie but that is a different issue.
Originally Posted by makeinu
This can't possibly be true. Maximal traction is achieved by maintaining static friction between the tires and the ground (ie not skidding). Additional feedback to the rider helps the rider to maintain static friction. A drivetrain that kicks back provides additional feedback to the rider. Therefore, drivetrain does have a bearing on traction.
Accepting your definition, here is where your inexperience with fixies is apparent. When pedaling forward you have just as much feedback regarding traction fixed as free. When backpedaling you do indeed have more feedback but it is coupled with the inability to apply an even force to rear wheel.(remember what I told you in your folding thread.)
But the problem is even more fundamental then that. Traction is not as you define it. If it was abses and tcses in cars would improve traction. They don't they improve what the car does with the same amount traction by controlling the car more finely then any human could.