I brought my road bike to work today. A group of us are going to ride 17 miles after work on Wednesday morning.
I have a QR seatpost rack to carry stuff. Unfortunately, my LED headlight was on my MTN bike, so I went without. It was certainly bright enough this AM, and there was no traffic to speak of.
I push a lot harder on the road bike, so it was bound to be a faster ride. I friend of mind road my route, but took a couple of different detours that I had avoided due to hills. I decided I could take the hillier route today. It was faster with a 30 mph downhill stretch that really makes up time.
I also have been leaving 15 minutes later. I have commuted all summer and haven't had a problem. I usually arrive to work 45 minutes early in order to shower and just in case of a flat. I could have a flat with my truck just as easily, and would probably be later for work if that happened. So, I choose not to worry about a breakdown.
I ended up with a 15 mph average for the ride and arrived 10 minutes earlier than I had anticipated. That means 10 minutes more to sleep in before the next ride!!!