Like Eric F, in the past my trick for doing this was to plan in advance to do long rides home after work. I'd bring an extra lunch and change of clothes in my panniers on my usual commuting bike one day, then the next day ride in on my road bike (at commuting pace to avoid getting hot and sweaty) then take an extended sporty ride home after the day at work. But if you have the luxury of a shower available where you work, then I'd consider leaving clothes and grooming essentials there and getting a good workout in on the way to work - or if you work someplace extra awesome, take long lunches and ride then!