There's also a "non motor-paced" category of records which does involve pedaling from a standstill to the maximum speed. Presumably involving many shifts. They are not surprisingly slower, because just as in driving a car, accelerating requires the most power, and maintaining speed much less. A multispeed bike would have more frictional losses in the gearing too. If she tried to get to 183.9mph from 0, on a bike with an appropriately large number of gears, she would probably be tired out long before she got to that speed.