The main reason boxer briefs ride up is they are too small for you or the wrong cut. I've bought enough brands and styles to understand that not all brands and styles are made for all guys. For instance, the Hanes boxer briefs ride low on me. They're too tight in the rear which makes them not ideal. The same size with Calvin Klein Cotton Classics does not have this problem. They are roomier in the rear. If your boxer briefs are riding up, they are the wrong cut, style and/or size.