Tour organizers had said he was being disrespectful by agreeing to join former soccer player Geoff Thomas' One Day Ahead ride to raise money to fight leukemia. The philanthropists are taking each stage a day ahead of the regular Tour riders.
Armstrong, 43, won seven consecutive Tours (1999-2005) but was stripped of those titles in 2012 for doping.
"I understand people's reactions," Armstrong said. "I understand there are still some hurt feelings, and that's a process I'll walk through for a long, long time."
Armstrong responded to critics by saying, "We were all riding in an unfortunate era" in which doping was rampant.
A right elbow injury forced Serena Williams to withdraw from the Swedish Open on Thursday.
Williams offered no details of the injury, which was incurred during practice Thursday.
Second-round opponent Klara Koukalova advanced to the quarterfinals by walkover.
New England Patriots offensive lineman Dan Connolly retired Thursday after 10 seasons in the NFL.
The former undrafted free agent, who began his career with the Jacksonville Jaguars, played on the Patriots' Super Bowl team in 2014 and had been on the roster since 2009.
Connolly was signed to the New England practice squad in 2007 and was there again in 2008. He became a five-year starter for the Patriots in 2010.
ESPN will not re-sign Colin Cowherd when his contract expires.
The national radio show host is the latest outspoken personality to leave ESPN in 2015, following Bill Simmons and Keith Olbermann, as the network works to trim its budget at the behest of parent company Disney.
Cowherd has not announced where he will go next, but The Big Lead reported a reunion with Jamie Horowitz at FOX Sports could be in the works.