The owner of 15 Bike Barn stores is accused of advertising "half price" and "clearance" bikes which weren't discounted.
The Commerce Commission says it has filed 16 Fair Trading Act charges against Bike Retail Group and associated company Bikes International over alleged misrepresentations in 25 marketing campaigns between July 2013 and June 2015.
Bike Retail Group owns 15 of the country's about 20 Bike Barn stores, the commission said today.
The rest are owned by independent franchisees.
The commission alleges that Bike Barn's marketing campaigns were likely to mislead consumers about the savings available and that there was only a limited opportunity to get bikes at certain prices.
Bikes were allegedly advertised as being "half price" when they were usually sold at that price, the commission said.
Bikes were also allegedly advertised in a "clearance sale" when they were available at that price before and after the sale, the regulator said.
The commission said that Bike Barn had co-operated with its probe and that the retailer had indicated it intended to plead guilty to the charges.
Bike Barn national sales manager Victor Gardiner said the charges related to previous advertising.
"We are working with the Commission to resolve the issue. We have cooperated fully with the Commission's investigation, and we had already voluntarily changed our advertising in 2015 to address the Commission's concerns. The Commission has not raised any issues with our current advertising," Gardiner said.
"We believe our customers have always received a great quality bike at a low price at Bike Barn, and this will continue to remain the case. We would always encourage our customers to compare prices for bikes before they purchase. Since the matter is currently before the Court, we cannot comment further."