From oiling the chain to adjusting the gears or brakes, if the bike is securely fixed, you can work comfortably and use both hands. Even when using a minimalist floor stand that attaches to the rear triangle, the bike is very stable. If you regularly service your bike its best to get a two-, three- or four-legged stand. Clamped around the top tube or at the seat post, you can adjust the height on the stand to allow you to work from all angles. When folded, the stands usually take up hardly any space. Look for a clamp that can be rotated to give you maximum adjustability, quick-release fasteners for easy operation and possibly a tool tray too.