In the Prose Lancelot, there is an adventure in which Guinevere is (falsely) accused of being an imposter. Unfortunately, King Arthur believes the scam, so a great deal of time is spent on what should be done with her. Some of the barons declare that she ought to be put to death. Then, we get this passage:
Then Sir Kay the Seneschal came forward, so aroused that he almost called the king a false judge; he went up to the king as if ready to throw down his gage. At that, Galehaut looked toward [Lancelot] and gave him a sign, and Lancelot darted through the crowd, tearing away from his neck a cloak of rich orphreyed silk with ermine lining…. When he stood before the king, everyone crowded around to hear what he wanted to say, and many people gaped to see him come up without his cloak.
Lancelot was extremely handsome…when he had flung his cloak aside, he stood a half-foot taller than Sir Gawain, and he looked all the more striking for being clad in tunic alone. 
I’ve omitted some description here because I don’t think you need the exact proportions of Lancelot’s legs to get the point of this passage. The question is this: why is Lancelot more striking for being “clad in a tunic alone”?
The Prose Lancelot was written 1220-ish. If you look at the clothing from the 12th century, you’ll notice one thing that everyone had in common: robes. History of Costume notes that during the 12th century, men’s clothing was so long and voluminous that it even became a battle hazard.  Short tunics are usually depicted only on laborers. At the beginning of the thirteenth century, tunics started to become more common, but they were usually long with a shorter tunic or cyclas worn over them, and “The mantle was still the formal wrap for the man of distinction.”  Not until the fourteenth century do the short, clinging tunics that angered church officials start to appear.
In many pieces of literature, when a knight disarms, he immediately puts on a robe. I believe that the Prose Lancelot is written around the time when young men started wearing the tunics they wore underneath their armor rather than changing into robes. In this passage, Lancelot has not been in armor, but he has been traveling and he arrives ready for a fight (the fight doesn’t actually take place until the next day). He throws off his mantle. I won’t say he’s indecently dressed, but he’s dressed for a fight, not for the court.
I don’t need to explain that Lancelot is a young, highly attractive man. Anyone with even faint knowledge of Arthurian literature should know that. The point of this post is to draw attention to the fact that seeing a nobleman’s legs was uncommon. Dozens of passages describe Lancelot’s handsomeness in excruciating detail—this one is noteworthy because the surprise comes from the clothing. We spend plenty of time noting the shock when women began to bare their legs. Nobody ever writes about the shock when men bared theirs.
- Lacy, Norris J., ed. “Lancelot, Part III.” Lancelot-Grail: the Old French Arthurian Vulgate and Post-Vulgate in Translation (New York: Garland, 1993), 269.
- Payne, Blanche. History of Costume: From the Ancient Egyptians to the Twentieth Century, (New York: Harper and Row, 1965), 158.
- Ibid., 168.