As ktmdad said wear shin pads until you get real comfortable riding with the flats. I rode for a whole season without them and the first half of the season my shins were a bloody mess, but after about a month of riding with them, I never hit my shins again. It takes getting used to keeping a bit of weight on them so you don't roll your foot off of the peddle. Your foot won't slide, but the peddle will roll and bang. Once you get used to it though you shouldn't have any problems with banging the shins.