From TFA: "Mueller-Korenek sat on a bike with gearing so steep that she needed to be towed to around 100 mph before taking over under her own power." So no, she didn't just maintain 184 MPH.
It's also an engineering feat, but again TFA: "As they targeted the overall record, their team revamped the same dragster that was used to set the men's record" -- they're reusing last time's engineering.
Yes, she also needed to accelerate from 100 to 184, which (I am guessing) is a significantly lesser feat than maintaining a balance on a salt lake surface and keeping herself in 3 meters of a slipstream area. This is all remarkable, but the point was that this setup is probably not what most people would imagine when told of "a woman riding bicycle at 183.9 MPH".