Quick little update.....I just assembled my new Bob trailer, took it home, and was pleased to discover that my new Underarmour black bag is 1 1/2 lbs. lighter than the yellow bag that comes with.....and fits in perfectly! I'll simply pack a drawstring trashbag for rain protection, no big deal. BTW, the common critisism seems to be, "the Bob trailer allows you to pack to much, therefore you are unnecessarily too heavy". Since I'm being very precise with my cargo....I believe that aspect is irrevelant for me. Doyle