Brown was something of a living legend in the cycling community (especially to bike nerds such as myself), known mostly for his website that was packed with vast amounts of bike information. Although I didn't know the man, I've used his resources (on his website) quite extensively. He's a giant in the cycling word, and will be missed.
Here’s the message about his passing as posted to SheldonBrown.com:
“Dear…friends and customers,It is with heavy hearts that we convey to you the news that Sheldon Brown has passed away. Our thoughts go out to his family at this time. The cycling community has lost one of it’s most passionate members.”