Plaidophile

Aspect	Bicycle	BART
Distance under own volition	3 miles	1.5 miles
Average total time taken	30 minutes	30 minutes
Total active activity	30 minutes	15 minutes
Active-time side activities	Dodging cars and other bicycles	Listen to music, take interesting pictures
Passive-time side activities	N/A	Read, people-watch, post to twitter, check email
Cost per day	Seemingly unbounded	A bit under $3

I'll keep my bike around but I think I'll stick to a BART commute for the foreseeable future.