Fat Bob is a little longer at 92.1 inches in length vs. Street Bob's 91.3 inches. It's taller as well with an unladen seat height of 28 inches compared to Street Bob's 26.8. Ground clearance is very similar with Fat Bob at 4.7 inches and Street Bob at 4.9. They also hold around the same amount of gas. When you fill up your Fat Bob, you'll have 3.6 gallons. Street Bob holds a still-generous 3.5.