I'm a long time nature photographer, the 2 cameras I love for adventures when I don't carry all the big DSLR gear are a Canon digital elph SD700IS (when I need to go very light), Image Stabilization fantastic, allows for crisp photos without tripod, slips in the pocket. But, Canon has made the Elphs for years and you can find 4-6mp versions fairly inexpensive.
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My other favorite is the Canon G9, I don't use a case just sling it around my neck/shoulder, it's flat, light, doesn't bounce, has a built in lens cover, is ready for stopping and shooting anytime, and is rugged, has IS 35-200zoom. I have a small handlebar bag with a plastic ziploc if it rains, or gets nasty.

And if all fails there is the cell phone camera, good for snapshots

It's fun to document your journey, bicycling is ALL about the journey.