I drive a truck when I go riding, and my gear bag is out in the elements. For rainy riding trips I pack my gear into a plastic storage bin. Suitable tubs can be found for as little as $7 at building supply stores! I made a long trip in pouring rain and my gear was completely dry. As large as the storage bin I use is, it still fits between two bikes in a mini truck, and it fits ahead of the footpegs. Some even have the option of padlocking the top or even locking the tub into a truck.