I rode about 25 miles non-stop from my apt in the city to my mom's house in the suburbs last saturday. I was carrying probably 25-30 pounds of laundry and books in an old internal frame backpacking pack of mine with a broken hip belt, so the entire load was on my shoulders. It was not the most fun ever but i managed, it would have been way more enjoyable and way less painful on my back had the hip belt been working. If you really will be hauling 30+ pounds of stuff I would highly suggest getting a pack that has a nice padded hip/waist belt, as it is much easier, and better for your back to carry weight on your hips rather than on your shoulders. Check out some internal frame packs from an outdoor sporting goods store such as REI.