I have a few ways around this issue. If I have to ride in my dress/long pants then I use a pant/cuff strap. My preference though is to wear cycling shorts if the commute is longer than 5 miles. I'll either wear mountain bike specific shorts or road bike shorts with cargo shorts over them. I'm also not so modest as to not go in road bike shorts. My plan upon arrival is to change immediately and most of my Co-workers understand if I just came in rolling a bike that it stands to reason that whatever getup I have on will be changed to business attire as soon as the bike and any other needed cargo is attended to.