The finale was run in slow motion as Ledanois, who attacked inside the final three kilometres, began to feel the full effect of the uphill finish to the 162.2km race in Richmond, Virginia.
Consonni reacted as the Frenchman began to tie up but fell just short of catching him at the line as Turgis trailed a few seconds back.
The race opened with a regular chopping and changing of the lead for the first 60km but settled down when a strong five-man selection made its way forward.
The group contained Ireland’s Eddie Dunbar, who later suffered for his efforts, Italian Davide Martinelli playing a watchman’s role for his team and Jose Luis Rodriguez of Chile.
As attrition took its toll the break was reduced to three, with Rodriguez the last to be swept up just before the bell lap.
The Chilean was quickly replaced by Soren Kragh Anderson (DEN) who led through the start finish banner for the final lap but it was still too early for the race to be decided.
With the peloton now frisky after hearing the bell, the Dane’s lead only lasted a few kilometres further and the race came together until Ledanois made his winning move.
The best Australian finisher was Jack Haig who finished in 13th place with the rest of the trailing field.
"The guys rode really well throughout the race, I managed to finish 13th and Alistair (Donohoe) was 20th, which is pretty good considering he had a pretty unlucky race with a bike change and crash." Haig said.
"This is his first under 23 world championships and hopefully her can go on and do better next year as well as Nick Schultz he rode really good race he has another year as well.
"It has been great riding with the team this year. We had a really good bunch of guys and pull off some good results. I'm happy to graduate on to Orica-GreenEDGE next year."
Americans go 1-2 in the women's under 19 road race
Earlier in the day, Chloe Dygert and Emma White of the U.S. finished first and second in the junior women's road race following their 1-2 performance in the time trial this week.
Dygert rode solo off the front of the lead group on the final circuit of the course through Richmond. White finished 1 minute, 23 seconds behind for her second silver medal this week. She held off Poland's Agnieszka Skalniak on the long finishing straightaway on Broad Street.
“All I wanted” at the start of the week “was to see the U.S. on the podium,” Dygert said. “To go 1-2 twice…what can I say? That’s just amazing.”
Jessica Pratt was the top rider for Australia, finishing ninth. Team-mate Anna-Leeza Hull finished 21st.
"We expected it to be a reduced bunch sprint, which did happen but we expected the fireworks to happen on lap three but they happened quite early on lap two before the climbs so that surprised us a bit," Pratt said.
SBS will broadcast the elite women's road race on Sunday 27 September from 2:50am AEST on SBS/HD with streaming available right here on the Cycling Central website.