You'd need a good bike and also be an elite cyclist/sprinter. I can usually manage 30kmh for an hour or so (providing there's a good tailwind and I'm going downhill), but the issue with going faster is the air resistance which is roughly proportional to the square of velocity (rolling resistance is roughly proportional to velocity so that becomes less important). Going twice as fast will mean quadrupling your power output.
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You'd need a good bike and also be an elite cyclist/sprinter. I can usually manage 30kmh for an hour or so (providing there's a good tailwind and I'm going downhill), but the issue with going faster is the air resistance which is roughly proportional to the square of velocity (rolling resistance is roughly proportional to velocity so that becomes less important). Going twice as fast will mean quadrupling your power output.
Almost -- power is equal to force multiplied by velocity, so double the speed is 8x the power considering only air resistance.