To save any arguments. From wiki -

The peloton (from French, meaning little ball or platoon and cognate to the English word pellet), field, bunch or pack is the main group of riders in a road bicycle race. Riders in a group save energy by riding close (drafting or slipstreaming) near (particularly behind) other riders. The reduction in drag is dramatic; in the middle of a well-developed group it can be as much as 40%.

The term is also used to refer to professional cyclists in general.

Your welcome :-)

Both definitions apply to my comment that the peloton passed in a few seconds while the amateurs were spread across a number of hours.