Kiwi cyclist Linda Villumsen battled heavy rain and a slick surface to finish 18th in the women's road race at the London Olympics.

The 27-year-old, the sole New Zealander in the 66-strong field, crossed the line in a group that was 26 seconds behind winner, Dutch star Marianne Vos.

Vos, a gold medallist on the track in Beijing, outsprinted British rider Lizzie Armistead and Russian Olga Zabelinskaya at the end of the 140km race.

It became a race of attrition as the stronger riders repeatedly attacked and the peloton steadily lost riders because of the high pace.

As the race headed back to London, Zabelinskaya initiated the key move.

She went clear and Armistead, Vos and American Shelley Olds were able to join her.

The quartet quickly built a lead of about 30 seconds before Olds dropped off the front group inside the last 30km, leaving her three fellow attackers to decide the medals.

The Denmark-born Villumsen, who was fifth in the road race at the Beijing Olympics before switching allegiance to New Zealand in 2009, is focused on Wednesday's 29km individual time trial.

She has collected three world championship medals in the discipline since 2009.

NZ Newswire