The general attitude toward nudes in advertising in the 19th and early 20th century were not dissimilar to the attitude toward nudity in fine art.

Generally speaking, nude art that had some kind of historical or mythological background was fine, but nudes of contemporary women in contemporary settings were considered much more shocking and risqué. It's why Cabanel and Bouguereau's depictions of the Birth of Venus were both considered beautiful and respectable works of art, but Manet's Olympia caused a furor. Orientalist nudes, like of Odalisques in idealized harems, were also far more acceptable than those of contemporary European women.

Most nude ads I've seen from the 19th and early 20th century are tended to have ostensibly historical, mythological, or Orientalist subject matter, which is probably why they don't seem to have drawn much contemporary criticism.

You might find this interview with Patricia Tilburg interesting. It's about women working in the garment industry in France at the time you're curious about. It talks about their sexualized image and their depiction in advertising and gets into ideas of working women, their independence and their sexuality as popularly perceived.

https://newbooksnetwork.com/working-girls

Nudity has a strange and odd history as to how societies have viewed it over history. But as what you're asking about is most likely the Edwardian influence on that era in Europe. With the death of Queen Victoria, the prudish Victorian era had come to a close and the more flamboyant and and open Edwardian era began. King Edward VII was a bovivant and loved the excesses of life. This translated into a freer society in terms of nudity and sex. Also this was a time of "accepted" medical practices and the "settled science" of the day were being questioned which lead to a growing interest in naturism, basically nudism in the woods, countryside, beach resorts, anywhere away from cities of smog, pollution and disease. The women on bicycles are probably advertising for a naturist resort where clothes were barred, people bathed regularly, focus was on a healthy diet and daily exercise for the time the person spent there, the naturism movement spawned magazines (one of which H&E which stands for Health & Efficiency was started in 1900 & continues today to be in publication) posters and short movies. Naturism was about reconnecting with nature by being naked outside but also about better health and over all quality of life, naturists often didn't smoke or consume alcohol which was more than unusual at that time. The opposition to this came from the United States where it was seen as pornographic and sinful and these posters, magazines and films were largely banned, people caught in possession, mailing them or buying them could be arrested and jailed.