In round numbers, the drivetrain causes about 4 watts of loss. Tire rolling resistance costs about 40 watts (on regular roads with road bike tires; less in a v

In round numbers, the drivetrain causes about 4 watts of loss. Tire rolling resistance costs about 40 watts (on regular roads with road bike tires; less in a velodrome and more with knobby, thick mountain bike tires). The bike itself costs 8 ~60 watts or so in air resistance, less for aero, deep-dish tri bikes and more for round-tube wide-tire gravel bikes. But more importantly, air resistance increases with the square of velocity, no matter your starting drag coefficient. The remaining 150 watts or so are caused by rider air resistance. And of course, all 250 watts are produced by the rider and dependent on their fitness level. Clearly, the best way to go faster is to put more energy in. Next, improve your posture to produce less drag. However, it's easier to spend money than to sweat and suffer, so people instead turn to aero bikes, tires, and the drivetrain.