Designed to fit under the rear of the saddle, these are a great way to carry a spare tube and a few tools, permanently attached to the bike. Larger ones can also hold a small pump and whatever else you want to squeeze in. Saddle Bags from Tioga, Topeak and Vaude are available from Moruya Bicycles, on-line or in-store.
The bags attach to the saddle either using straps (cheaper and less rattly if you do the straps up tight), or a quick release attachment - the easiest to attach and remove. Bag Size. Road bikes have tubes which fold up quite small compared to mountainbike tubes, so small packs are commonly used on road bikes. Clearly, the more you want to carry, the bigger the bag. Do you want more than one spare tube? A pump? A snack?