I have a Jansport backpack I use for more or less everything except hiking. It's sold as a outdoors pack, but in reality is a horrible hiking pack. Anyways, I resorted to tying the waist strap in knots because it tends to get caught under the saddle when I start. For example, standing with the bike under me and one leg on the ground, I press one pedal to get the bike going and to lift myself, up, the waist strap catches on the nose of the saddle and traps me in a weird riding position until I can safely stop.