I carried a new battery for my wife's minivan. I didn't weigh it but car batteries aren't light, I'm gonna estimate 40 lbs. Enough to get rim-to-pavement contact when I hit a pothole at 35 mph (yeah going down the hill was a blast. Climbing 300 feet on the other side SUCKED ***).

I'm sure we're gonna get trumped by someone with an extracycle who carried the bricks to rebuild his garage or something .

[edit] Am I a good guesser or what. According to Autozone.com, the battery for that vehicle is 38.4 lbs.