It was beautifully sunny, not a cloud in the sky (this kind of weather is why I love Colorado). Of course, clear skies also mean it's windy. Also, cloudy skies. Or partly-cloudy skies. Or thunderstorms. Okay, it's just generally kind of windy here (not Chicago windy, but still). And, of course, it was a headwind on the way back again, which is always annoying.
At any rate, rode to the end of the Sulphur Gulch branch instead of to the end of the paved part of the main Cherry Creek trail (which I did, er, Monday). Which was more uphill than I'd realized climbing it -- I was (once again) annoyed that my bike didn't gear any higher when I was cruising at ~22mph back downhill (at that point, you're pedaling fast enough to be losing mechanical efficiency in the top gear. And the max speed today? That was cruising, not a brief spurt down a steep hill or anything).
That said, it's just as well I wasn't going faster. I did run a couple of deer off the side of the trail (scary high-speed human!), and was going too fast into one of the underpasses when I didn't realize it turned so sharply in the shadows.
And there was a rattlesnake head I just missed crushing, but that was later back on the main trail, I was only going about 16mph at that point.