I've used a 2 x 4 lying across the front of the bed with blocks on either side of the front wheel as a cheap alternative to a real chock, and then I've used nothing but 4 good nylon ratchetting straps. Never lost a bike yet, but one word of advice- when you release the bike be sure your kickstand is ALL the way down- I dropped my bike & dented fuel tank by forgetting to check. The stand rode up a bit and when I released the straps on the right side over she went
