I'm going to try tightening them down the next time I ride. I think another issue may be the shoes I'm wearing. I wear Merrell Tough Gloves when I commute since those are the shoes I wear at work. They're part of Merrel's barefoot line, so are an incredibly minimalistic shoe. I have a feeling for me to make the straps tight enough to stop my foot slipping in these shoes it may be so tight I can't even get the shoe in the strap. Could be wrong though.