COMPIÈGNE, France (VN) — Retired superstar Tom Boonen has been dropping some bombs lately. Earlier this week, he said Peter Sagan (Bora-Hansgrohe) should “keep his mouth shut” instead of complaining about rivals marking him.

On Saturday, in an interview with Belgian television, Boonen breached an even more sensitive topic. When asked if Fabian Cancellara might have used a motor to beat him in the 2010 Tour of Flanders, Boonen gave a surprising answer.

The interviewer asked, “Did Cancellara steal the 2010 Flanders thanks to a motor? Is there any doubt?”

Boonen replied, “Yes, but it’s not for me to say. I finished second and it’s the one in second who has to say the situation is not normal. It’s very difficult to prove because we do not have the bike to check. It’s too late.”

Read the full interview in French here.

That is Boonen’s most public comment yet about a story that’s been churning on the edges of the peloton for years.

Some claim that Cancellara used a motor to power away from Boonen in a classic showdown on the Kamelmuur. Cancellara won that year’s Flanders 1:15 ahead of Boonen and won Paris-Roubaix a week later.

Cancellara has always vigorously denied the allegation, once saying half-jokingly, “The motor is in my legs.”

That hasn’t stopped a series of online videos and rumors from fueling the story for years.

The Cancellara motor story has taken on new life in wake of news that other riders have been caught using motors in competition. Retired pro Phil Gaimon also kicked up a storm when he mentioned the Cancellara rumor in a book released earlier this year.

Boonen did not expand on his controversial Cancellara comments in the wide-ranging interview.

When asked what was his favorite race, Boonen answered with aplomb, “The Ronde is the biggest race … in Belgium. If I had to say, I would say Roubaix every day of my life. Roubaix is the biggest race in the world. If you ask an American, they will know what Paris-Roubaix is. Flanders is the biggest race … in Flanders.”

Boonen also clarified why he recently signed a deal to help Lotto-Soudal instead of becoming an advisor to his long-time professional home at Quick-Step: “There are some people who are not happy about it. For a year I had almost had a deal signed with [Quick-Step manager Patrick] Lefevere, but it never came. I am not a guy who is going to call every day to find out if there is still a place for me. Of course, I have to admit it’s a bit awkward because I still love the Quick-Step team.”