I see a lot of references to sheldon brown on this forum, and wanted to give respect where it is due.
Sheldon is a nice guy and knowledgeable but the main thing that distinguishes him is his media exposure. His website is accessible and often cited. (for example the persistent use of "gear inches" an anachronistic and baffling system that even he has recommended moving on from).
But he is not alone.
I think other bike devotees of similar caliber deserve recognition. Though they do not have websites or there sites are les well known in amateur ciircles.
Dave perry runs bikeworks in NYC, he is the author of bike cult and husband to Taliah Lempert, the famous bicycle portraitist.
Paul Reigart is a frame builder, bicycle archivist and mechanic here in Washington DC. He was at school with Miyazaki and knows endless amounts of trivia about the industry.
Larry black is the proprieter of Mt. Airy cycles and along time bike advocate, archivist, and businessman in the washington area.
Add your own sages.