Winder was awarded the win by officials after she surged in the closing metres before the line to pip Vollering by the finest of margins.
It was a painful defeat for Vollering who thought she had done enough to win the race and celebrated before she crossed the finish line, only to be edged out by Winder at the death.
"I'm extremely surprised," Winder said.
"I came to this race wanting to be my best, and in the end, it played out really well for me. I thought Demi had it.
"We were sprinting and I threw my bike at the line, but she really celebrated, so I thought 'congratulations' because she is an amazing bike rider and just for me to be second, I was excited with that. To win is … it feels really good."
Vollering controlled the race heading into the final 1.3km climb after making a move 20km out from the finish in a six-rider breakaway.
Elisa Balsamo made a break for it over the crest of the climb but faded early as Winder and Vollering swung off her wheel.
Vollering thought she had done enough in the head to head sprint and threw up her arm in celebration just before she crossed the line which gave Winder a chance to snatch victory in dramatic style.
Sarah Gigante was the best placed Aussie rider in 32nd place followed by Lauretta Hanson in 39th and Neve Bradbury in 41st.