Tokyo residents haunted by the memory of how the March 11 earthquake shut the world's busiest subway system are returning to bicycle travel, tripling the sales of retailer Asahi Co. in the area last month.

"I was in Tokyo when the earthquake hit, and everything stopped," Asahi Co. President Susumu Shimoda said in an interview. "Trains stopped, buses were in chaos and cars were jammed. Within that, you could just see bicycles swimming through. Some of our stores stayed open until 4 a.m. to meet the surge in demand."

Asahi, the best performer on the 146-member Topix Retail Trade Index this year, has gained 8.6 percent since the magnitude 9 temblor and the tsunami. Tokyo's subway system, which transports about 8 million riders daily, halted operations on March 11, forcing commuters to wait hours for taxis, search for a place to spend the night, or walk home.