NEWTON, MA — Did you buy a bright yellow vintage touring bicycle with flat tires and some dust on it Sunday between 10 a.m. and 11 a.m. from a man at a yard sale in Newton? Did you put the Motobecane Grand Touring bike with straight handlebars in your silver or white sport utility vehicle and worry aloud about how it would fit before driving off?

There's been a mistake. Please come back. That's the message Allan Steinmetz is praying the buyer, who he described as tall man and in his 40s or 50s, will see and reach out to him. You see, the bike has a priceless sentimental value to his wife and Steinmetz said he made a "huge mistake" by selling it.

"I'm prepared to pretty much pay about anything to get it back," a bespectacled Steinmetz told Patch from his backyard as he wrung his hands. "I underestimated what it meant to her at that moment. I shouldn't have done it."

He plastered Newton Center and the corner of Centre Street and Clinton Place — the site of the yard sale — with signs imploring anyone with information about the bike he sold to get in touch.

One of Allan Steinmetz's flyers in Newton Centre. Jenna Fisher/Patch Sunday morning, Steinmetz saw that his neighbors were holding a garage sale. Since was cleaning out his basement to have his own yard sale in a couple weeks, he started pulling things out to sell. It was an impulsive move, and he was immediately swamped with people ready to make a purchase. That's when he sold the 43-year-old bike that was in the basement collecting dust.

"I wasn't thinking," Steinmetz said. "I sold it to him not thinking about the consequences of the sentimental value, which was priceless. It was a special bike to her. We moved it three times — from Detroit to Chicago to Boston. " He said he should have known better.

His late father-in-law, who had survived the Holocaust and concentration camps at Auschwitz and Bergen-Belsen, gave it to her on her 16th birthday. What's worse, he would have been 106 years old the day Steinmetz sold the bike; It was the four-year anniversary of his passing.

Her father always prided himself on buying the best.

"He always wanted to make a statement that he overcame the concentration camp and prejudices," Steinmetz said.

So he went out and bought probably one of the most expensive bikes at the time.

"He specifically put straight handlebars on it, because he wanted her to stand tall while riding it," he said. "It had a special license plate on it that said 'ride a bike and don't get fat,' and it meant a lot to her. And I sold it. And I made a huge mistake." When Steinmetz realized what he had done, his heart sank. He was angry at himself and embarrassed. His wife was planning on restoring the bike and passing it down to their granddaughter.

