That depends. Different log bars have different dimensions and diameters, all of which have their own unique advantages for training. While eight-inch log bars weigh 50 pounds, their 10-inch cousins are closer to 72 pounds. And 12-inch log bars can get as heavy as 134 pounds.
Smaller bars allow you to train with a bigger range of motion. So even though they’re lighter, they might challenge you more since you have to push them through more time under tension due to the larger range of motion.