Bicycling is responsible for a $668 million annual impact on Michigan's economy, according to a study commissioned by the Michigan Department of Transportation.

The study found that household retail spending on bicycles totals $175 million and that the actual manufacturing of the bicycles comes to $11 million.

Bicycling leads to another $256 million in avoided health care costs and reduces absenteeism at work by $187 million.

The final $38 million comes from event and tourism spending.

Some 39 percent of households reported using a bicycle for transportation last year, and the bicycle industry employs nearly 800 people in the state.

The study conducted by Denver-based BBC Research and Consulting found about one-third of people use their bicycle to commute at least one day a week.