Grace Brown has been left frustrated that she's managed to achieve a career first in her very last road race — by pulling out over dreadful conditions.

Australia's world and Olympic time trial champion is in the final week of her magnificent career but it got off to a bit of a soggy false start when she abandoned Tuesday's rain-soaked Tre Valli Varesine race in Italy.

Worried about race safety, the 32-year-old, hoping for a triumphant road race farewell with her French-based FDJ-SUEZ team, decided to voluntarily quit the dangerous roads after she and Aussie colleague Brodie Chapman failed to get assurances from race organisers.

"Not exactly how I envisaged my final road race at Tre Valli Varesine in torrential rain and flooded roads," Brown explained in an Instagram post.

"Here's a 'nice' photo with my backwards breakaway companion @brodie_mai after we tried to speak with the commissaire car about race safety. We achieved nothing other than getting dropped from the peloton in the process.

"So, even in my last road race, I achieve a first! I voluntarily abandoned a race for the first time in my career.

"Only 35 tough women battled the conditions to finish, and the men's race after ours was eventually cancelled."

Brown said she is hoping for better conditions at the Chrono des Nations on Sunday in Les Herbiers, Vendee in the west of France, a time trial which she says will definitely be her "last hurrah" in cycling.

Sunday is her last chance to wear the rainbow jersey there as world champion — she won two at last month's championships in Zurich in the individual and mixed team time trials — to put the golden seal on her magnificent career.

AAP