I have tried various bags for my commuter bike and this is the best so far. The sides have remained stiff. The fold-out panniers are robust. One side easily fits my sandwiches and the other my fruit. The main bag holds a shirt and trousers. The panniers then fold back in as niether the sandwiches nor the fruit make the return journey. The inclusion of a flourescent cover, which stores in a net under the top lid, is very useful. This stretches over, and holds itself onto, the entire bag, including panniers. I would advise always useing this as it protects the bag from road spray and crud.