Not sure if it's because I'm extremely short, or what, but over a very short amount of time, the space between the knee and the shin armor pieces began to fold, placing the knee under the shin. This ended badly for me in a crash at the bike park when the knee plate dug into my shin so hard that I ended up with a golf-ball sized bruise that took months to go away. Too much space between the plates, and not a firm enough backing material to prevent folding. As other reviewers said, they also have a tendency to pop open, and are very difficult to lock/unlock at times. I'm much happier with my Raceface DIYs (the women's version of the Rally FR).