When sunny is bad and cloudy, best

If you mountain-bike, chances are you'll do it early in the morning or late afternoon, when the sun is often at a blinding angle and shadows are overly long, making for stark contrast between sunny and shady sections of the trail and seriously limiting visibility, particularly in those vegetated single tracks.

Since mountain-biking is all about visibility, this can be annoying and that's why we always welcome an overcast day, because it makes for a shadowless, well contrasted view. In the American West where sun is king from June through October, riding on cloudy days is rare and priceless!