AMES, Iowa -- Dozens of Iowa cyclists were sidelined by a possible prank during their ride Wednesday morning, reported KCCI-TV in Des Moines, Iowa.

"I heard a small pop out of the tire," said Doris Sherman, a participant in the Register's Annual Great Bicycle Ride Across Iowa, or RAGBRAI, which is a more than 400-mile ride across the state.

Sherman pulled over in Colo, Iowa, where she found dozens of other cyclists lined up at a repair shop. That's when she discovered the source of her problem, a small tack.

Story County Sheriff Paul Fitzgerald said tacks were dumped along the white lines of the eastbound lanes in three different stretches of old Lincoln Highway.

"Bikes have been falling off left and right with tires. I've come across some people who have had gone through three or four tubes on their bike tires already," Fitzgerald said.

Dave Hendricks, who was fixing the trashed tires, said his crew had pulled at least 50 tacks out of tires in just a couple hours.

"We got here about 6 o'clock and they started showing up right after that. We've been repairing mostly tubes here, bunches of them," Hendricks said.

County road crews carefully navigated through the crowd of bikers trying to clear the road of any additional tacks.

"It's too bad that some people are inconsiderate of others, but we riders still go on. (It) doesn't stop us from riding," Sherman said.

Sheriff's deputies are looking into the case, but they said it's difficult because while they assume the tacks were intentionally placed along the road, they don't know that for sure.