I ride 15 miles each way and the time difference between my morning and afternoon run is around 10 mins too... sometimes longer.
Once I get on the bike path I like to take off my helmet in the morning and get the breeze so I take it slow. But on my return trip
I keep my helmet on with a average +5mph on my way home.

Occasionally I would run into someone on my way to work and follow their pace but thats if I'm in the mood.