Originally Posted by
OneIsAllYouNeed
At that distance, I'd mix it up. On hot, rainy, or snowy days, I'd suit up for cycling. On cool, dry days, I'd dress for work. Furthermore, I'd do bonus miles some days, which would definitely require spandex.
+1
I had a similar commute once, and did not use cycling clothes. This resulted in some problems, particularly toward the end of the week and in extremely hot weather.