Mr. Williams, an amateur racer and former captain of the Yale hockey team, also had become friendly with Mr. Armstrong. Mr. Williams pledged $1 million to the Lance Armstrong Foundation, which helps cancer survivors, and raised money from others. But some two years after Tailwind's breakup, his dealings with Mr. Armstrong soured.
A company Mr. Williams co-owned, eSoles, wanted to sell athletic shoe liners bearing the Armstrong Foundation's "Livestrong" logo. Mr. Williams believed he had been given that right in exchange for his pledges to the foundation. But the foundation—which had an agreement with Nike, one of Mr. Armstrong's top sponsors—said no.
On April 29, 2009, Mr. Armstrong was preparing for a race in New Mexico when Mr. Williams emailed asking to speak to him immediately. Mr. Armstrong's response came just over an hour later.
"To be honest, and I say this as a good friend of yours, I don't feel like dealing with this right now," he wrote. "I'm afraid it's up to you guys to sort out. For what it's worth, and maybe a good solution, is to return you all of your money and let's all get on down the road."
Mr. Williams's logo plan unraveled, and the foundation declined to return his donations. A foundation spokeswoman says it doesn't "accept donations with strings attached" and "never had a formal relationship with, or entered into any agreement with, eSoles." Mr. Armstrong's lawyer, Tim Herman, said the foundation released Mr. Williams from the two or three remaining years of his pledge.
Mr. Williams was furious, say people familiar with the matter. He talked about suing Mr. Armstrong and said he considered their friendship over, these people say.
Late last year, after Mr. Landis's comeback fizzled, he again began thinking about speaking out about doping. He reached out to Mr. Williams, who told him the story was bound to come out and that Mr. Landis should make sure whatever he said was accurate, Mr. Landis says. Mr. Williams has said that his advice wasn't influenced by his dispute with Mr. Armstrong, according to Mr. Landis and a person familiar with the matter.