Well then you would have to debate on whether or not it is worth leaving early to bike to your destination. All depends on how you value your time.
Also depends on where you are going. i.e. you don't want to show up to work sweaty or tired right?
Then there is the risk of getting injured riding a bike. It will happen, especially in the city.
Fyi don't bike when it rains, snows, hurricanes, etc
I would just use the subway