Ulla Oderyd and Eveline Olsson said they locked up their bikes, which both belong to Olsson, on a rack outside the thrift shop in Gavle and emerged to find the bike Oderyd had ridden was missing, Swedish news agency TT reported Thursday.
The women said they asked employees if they had seen the bike and were shocked to hear it had been sold.
"I asked them; 'Do you sell locked bikes?' I didn't get what they were saying," Oderyd said.
Goran Lofjard, manager of the store, said he mistakenly sold the bike because it had been on a rack filled with for-sale bicycles. He said bikes sold at the store often have locks on them because they frequently come from the estates of deceased people. The bike, which Olsson purchased for $758, was sold for about $50.
Oderyd said she was relieved when the person who purchased the bike read about the incident in a newspaper and returned the item.
"Thank goodness," she said.
Lofjard said the store also sent flowers to Oderyd and issued her a voucher for $75.
"We should have marked the stand with a sign saying those were bikes for sale," he said.