The Luxembourger broke his hip at the Criterium du Dauphine, missing four months of action including the Tour de France and Vuelta a Espana.
The RadioShack-Nissan rider took part at Tuesday's Binche-Tournai-Binche and, while he did not finish, he believes he is in good shape for the end of the season.
However, he stopped short of saying he was fully fit, targeting the start of next season for a full comeback.
"My pelvis still hurts sometimes but I can ride,” he was quoted as saying by Cycling News. “To be clear, that inconvenience is not the reason why I stopped today, and please don't call this my comeback.
“My real comeback will be next year when I will be in good shape at the start of 'my' races. I am motivated!"
Schleck stuck with the peloton in Belgium on Tuesday before withdrawing ahead of the finishing section.
The ride gave him confidence but he admitted to playing it safe when the going got tough.
“It was not the ideal race for me to come back in the peloton – flat, fast, rain, wind, almost a Flanders Classic – but I don't regret it.
“It was a nice feeling to see the people waiting and cheering for me.”
The Tour of Beijing begins on October 10.