Cars keep me plenty of company.
There is a myriad things to reckon about.
Road clarity, pedal stroke, traffic, people and things around you, past, present, future, new ways to ride, old ways to ride, gear ratios, rain, wind, politics, spirituality, plants, music (in a non listening way for me), birds, .... and I always bring my VDCM (visual digital moment capture device) in a case I notice a present vision I'd like to not have to just remember as my memory is not that accurate.
Edit: VDMCD to be mo' axact