Miller, who looks younger than his 82 years and has a patient way of speaking, recently put a "new business" ad in the paper. He's also been working with the West Philadelphia neighborhood's community development corporation to find a buyer.
Along the seven blocks from 38th to 44th Streets, once an industrial corridor, there's a mix of striving and surrender.
On the low-numbered end, some fallen storefronts have been converted into shiny art galleries and student housing. Throughout the stretch are niche businesses, such as the cabinetmaker, among the slew of Chinese restaurants, pizza shops, day-care centers, and hair salons. There's also a high vacancy rate, on some blocks as high as 20 percent, according to James Wright, commercial corridor manager for the People's Emergency Center CDC.
"It's a challenge trying to fill gaps," Wright said. "People think of the corridor as a place of convenience, and we're trying to show them it can be more." The agency recently brought back "Second Fridays" to draw people to the avenue with longer store hours, specials, and live music.
One obstacle for the Wolff Cycle space is Miller himself. Despite the decline in business (Miller points to cheaper bikes at Target, his own lack of advertising, and kids idling at home in front of video games), he's firm that it must remain a bicycle shop. He believes in the shop and has rejected offers to turn it into something else.
"This is an institution," he said, arms folded. "And what do you do with an institution?"
"You can't just walk away from it," responded Phyllis, his wife of 56 years. Pleasant and bubbly, she often adds to his sentences. "We'd just hate to close the doors."
Wolff Cycle has survived 83 years on the 4300 block of Lancaster Avenue, with only two owners. It still carries the name of one of the original partners.
Looking to leave his uncle's construction business, Miller bought the shop in 1976. He had come in to buy bikes for his two boys, one of them with cycling promise, when the owners mentioned they were ready to move on.
Decades later, the store holds the sharp smell of rubber. Bikes are displayed on chipped red-and-black tile. Pedals and cranks hang behind the counter like flesh on meat hooks. A metal filing cabinet holds thousands of hard-to-find parts.
By the register is a row of repaired cycles awaiting their owners' return. One with $91 worth of fixes has been waiting a year. Miller eyed his shelter for homeless bikes and shook his head.
He got his first bike when he was 15.
"It was a piece of junk," he remembered. Then a sophomore at Olney High, he bought the used cycle for $5. "I had to tie it together with wire."
After he took it home and worked on it, "I used it for years, until I outgrew it."
Over his time at Wolff Cycle, he has learned more intricacies.
He started in the business with five mechanics. Waning business has brought that down to one part-timer. Gone are the Wolff bike racing team, the holiday turkey raffles, and other promotions. There are shorter hours, shorter weeks, and shorter work years.
"Once the kids go back to school, it slows down," said Phyllis, 81.
When the shop turned quiet, they reminisced.
They giggled over the guy who had laid away a $600 bike, which brought his wife barreling in, screaming. Carl Miller innocently asked her, "What do you want from me?" There was the sweet woman whose wheelchair had a flat. There was the gentleman, one of many second-generation customers, who got all mushy, realizing that his father had bought his very first bike there.
"It's a good feeling that people remember the shop," Miller said.
He tends to a steady stream of customers. A kid with a broken chain. A hipster with a slow leak. A sweaty guy in need of a receipt.
"You know that bike I just bought?" he asked Miller, his face tight with disgust. "Someone stole it."
Phyllis gasped. Miller offered his condolences.
"I had that thing three hours," the guy continued. For the police report, he needed a receipt for the silver Fuji.
After he left, Miller assured his wife, "I try to sell them a lock, even if it's cheap."
Such drama, and the hour's drive from their Whitemarsh home, are more reasons Miller is ready to retire.
His wife is also adamant. "He can't be idle," she said, and then reminded him of the partners, the previous owners. After they retired, "one lasted a year and died. The other lasted three years."
Miller smiled in response. He has plans. One is to finish restoring a 19th-century bike, complete with its kerosene head lamp.
They thought of passing the shop to one of their two sons, but Phyllis reasoned, and Miller agreed, that "young people don't like being confined."
But they believe there is promise, with the right energy.
"Somebody with fresh blood and new ideas," said Miller. "It can be brought up. It can be brought back."
It's almost noon when a pear-shaped man comes in, walking a royal-blue bike. He needs some adjustments to the cycle, which he purchased a month ago.
"I'm trying to lose some of my gut," the 51-year-old said, patting his potbelly. So he rides every day, everywhere. And, he testified, "you should see how my stomach went down."
Contact staff writer Kia Gregory at 215-854-2601 or email@example.com.