MADISON, Wis. -

In his second attack ad on the subject, Gov. Scott Walker once again slams Mary Burke's work at her family's company.

He never names the company in the ad, but he's talking about her work at Trek Bicycle.

"Mary Burke is trying to sell us on her experience at her family business," the ad says. "But she forgot to mention that they make 99 percent of their bikes overseas in places like China, where her company has outsourced for years."

News 3 finds this needs clarification, and there's no way to tell whether it's true or false because Trek won't disclose its production data.

The ad cites a 2011 article at Onmilwaukee.com, where Trek's public relations manager made some estimates of its production.

He said it was almost impossible to give a number of how many bikes were made in the U.S., but that it was somewhere in the 10,000 range. He admits that most of their bikes are manufactured overseas, but when asked how many, he said it was "hard to say" and that Trek sells around 1.5 million bikes a year.

If both of those figures were accurate, it would mean 0.7 percent of their bikes were made here and more than 99 percent were made overseas.

News 3 finds that while it's true that the company has outsourced jobs, it is not unique to Trek amongst bike makers. The National Bicycle Dealers Association says 99 percent of all bikes are manufactured overseas.

Mary Burke has used her latest ad to defend Trek.

"The real story? Mary Burke helped build Trek where almost a thousand people go to work every day, making more bikes in the U.S. than anyone," Burke's ad says.

News 3 finds this needs clarification. We can't prove the figure because Trek won't tell us exactly how many bikes it makes here.

What we do know is that the National Bike Dealers estimate total U.S. production of bikes at only 56,000 bikes a year amongst more than a dozen bike makers. In that 2011 interview, Trek claimed to make possibly 10,000 of those.

One other claim in the governor's ad says taxpayers paid for Trek workers to be retrained. News 3 finds that's also true, as Trek workers were eligible for trade adjustment assistance during layoffs in both 2004 and 2013.

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