There has been evidence that tariffs imposed from last October have been avoided by shipping Chinese bicycles through Indonesia, Malaysia, Sri Lanka and Tunisia, the Commission said in the EU Official Journal.
The investigation will also examine whether bicycle assembly operations using Chinese bike parts have moved to Indonesia, Sri Lanka and Tunisia just to avoid payment of EU duties.
The Commission said it was acting after a complaint by the European Bicycle Manufacturers Association (EBMA), the latest step in a long-running trade dispute with China.
The EBMA represents more than a quarter of a European industry that employs roughly 20,000 people, mainly in Germany and Italy.
EU sales of bicycles and parts total about €5 billion per year, including products from manufacturers such as Dutch Accell Group, France's Decathlon, and German's Derby Cycle and Mifa.
The EU first imposed duties on Chinese bicycles in 1993 and have gradually increased them since then. Last year it extended a 48.5% duty on bicycles imported from China until 2014.
Last October, the Commission said imports from Sri Lanka had almost doubled between 2009 and 2010 to take up 5% of the bicycle market in 2010, which could be consistent with circumvention of duties.
Under EU anti-dumping rules, the Commission has nine months in which to decide whether to levy additional duties and six further months to announce definitive measures.
The investigation is the latest in a series the EU has launched on trade with China, with cases so far this year including steel, solar panels and aluminium foil.
China, the EU's second-biggest trading partner after the United States, accounts for 16% of all imports, figures from the EU statistics office show.