The Longmont Times-Call reported Monday that 75-year-old James Ernst of Erie entered his pleas last week.
Ernst is charged with harassment, illegal use of a horn and driving two slowly.
Related Story: Driver suspected of harassing cyclists cited
He hung up the phone without commenting on Monday.
The incident occurred in September on a two-lane road east of Longmont. A video the cyclists posted on You Tube had been viewed more than 457,000 times by Monday, according to the website's counter.
(Copyright 2012 by The Associated Press. All Rights Reserved.)