I also always use four straps at front of the bike attached to four different tie down points on my trailer. I figure with only two straps, if one broke loose, a lot of damage could happen; four is cheap insurance if that should ever occur. Of course four front straps always has given me a lot of grief from whoever helps me load or unload, always saying it is overkill.I will add that when hauling in an open trailer I tend to be a belt-and-suspenders person, using two sets of tie downs at the front.