I use these straps from Bass Pro Shop. They come in many sizes and color. Really like them because they have no edges (even the hook is molded into one piece with the strap itself so they don't scrape paint off your bike or get all twisted around. They're insanely stretchy but also really really strong. They're about $4-10 depending on size. My husband has the black rubber straps you can get at Canadian Tire and after a while the rubber starts getting dry and cracked. No change to these.
