Zhuangzi made Liezi famous for his ability to "ride the wind", yet he also tells us that he was still using training-wheels. There are other ways to ride the wind which evince an even greater freedom. Wind riding might even be taken as a vehicle for understanding Zhuangzi's message in the first chapter of the Zhuangzi.
The mighty bird Peng, symbolic I think of existence, soars to ninety thousand feet for: "Only then can he ride the wind, bearing the blue of heaven on his back and unobstructed on all sides, and make his way south." (Ziporyn; ital. mine) This is the ride of necessity. Human existence requires struggle; if we wish to make the most of it, we'll need to beat our wings whether we are mighty like Peng or lowly like the cicada. This is "flying with wings"; always necessary, never obviated.
But Liezi went a step further; he realized a certain mastery of necessity which enabled him to use it effortlessly. The day-to-day mundane, chopping wood and carrying water, became for him an opportunity to soar. But still, without this achievement he would have felt a lack; he still depended on his accomplishments. He still flew with wings.
But what if, Zhuangzi asks, "you were to chariot upon what is true to both Heaven and to earth, riding atop the back-and-forth of the six atmospheric breaths, so that your wandering could nowhere be brought to a halt. You would then depend on — what?" This is "flying without wings", depending on nothing. What is "true" has already been offered as a matter for debate: Why is the sky blue? No conclusion has been reached; no matter, says Zhuangzi, wingless flight requires no answer. "Back-and-forth" (bian) is literally "disputation" and anticipates the opening trope of the next chapter where the trees hoot and holler as the wind passes through them. Though we must necessarily have our own hoot or holler, we can be more than our opinion of things; we can ride atop every opinion, even our own. No answers are fixed. No way alone is the Way; all ways are the Way. The Way is normative not as that which sorts through ways to find the truest, but as that which enables them all to arise while riding atop them all.
In a following story, the madman Jieyu tells Jian Wu about a "Spirit-Man" who "rides" should seem ridiculous; you'd have to experience it for it to be otherwise. Similarly, this anticipates a following story in which Huizi tells Zhuangzi that his philosophy is "big but useless". Of course it is, replies Zhuangzi; and this is precisely wherein one finds freedom.
No one flies anywhere, of course; to think so would not only be to fly with wings, but to try and do so inside a tiny cage. There is no Peng, Liezi took no actual magical flight, the Zhuangzian sage does not ride a heavenly chariot, and there is no Spirit-Man subsisting on "the wind and dew" while harnessing dragons. It's all ridiculous.
You can check out Scott's writings on Zhuangzi here.