I concur with the above, handlebar bag will be the most convenient.

I also second rperk's use of Micro Four Thirds and similar mirrorless cameras. They are small and light, and if you're printing 8x10s or smaller the image quality will be the same as your DSLR. High-end point and shoots will also be very good up to that size, though I'd treat it more as a backup than a primary camera.