One of the unwritten rules of driving is to try and not hold up or inconvenience the drivers behind you. People get aggravated with large farm machinery holding

One of the unwritten rules of driving is to try and not hold up or inconvenience the drivers behind you. People get aggravated with large farm machinery holding people up but understand that machinery has a purpose and needs to get from A to B. The same people think Bicyclists aren't trying to get from A to B but are just out for a ride and happily breaking the unwritten rule. That is where the outrage comes from, they think the cyclist doesn't care about the irritation they're causing the drivers so the drivers decide to take it out on the cyclists.