That defeat came with the Indianapolis Colts after the 2009 season. San Francisco's new safety also won a championship during his rookie season of 2006.
Bethea insists he is ready for another ring after finalizing his new $23 million, four-year contract with the 49ers on Wednesday, becoming a key new presence in the secondary after Donte Whitner's departure to the Cleveland Browns.
''One of the reasons I'm here in San Fran, to try to get another ring,'' Bethea said. ''That's what I'm here to do.''
Bethea announced Tuesday on Twitter he had joined the 49ers, then the team made it formal Wednesday.
The 29-year-old Bethea had 110 tackles, two interceptions and a sack last season, his sixth straight year starting every game for the Colts.
''Just as a football fan, you have to notice the talent they have on the team. You have to respect what they've been able to accomplish these last couple years,'' Bethea said. ''First of all, it's a winning organization. From the past couple years, from outside looking in, an extremely good team. It looks like they have a ball out there on the field. Coming in, knowing this defense, a great defense, a great front seven, a great back end, I just wanted to come in and do my part.''
A two-time Pro Bowler, Bethea was a sixth-round draft pick by the Colts out of Howard in 2006.
''Antoine is a durable, experienced player who has competed at a high level throughout his career in the National Football League,'' 49ers general manager Trent Baalke said. ''He has proven to be a man of high character and is a welcome addition to our team and the Bay Area community.''
He will be called upon to help lead the secondary after Whitner made the calls for that unit, and will work with 2013 top draft pick Eric Reid after his impressive rookie season.
''I'm ready for that. Eric Reid he had a great year,'' Bethea said. ''With us working together, we'll be fine. ... Whatever it is, I'm willing to do whatever I need to do to help this team win, for this defense to be successful.''
Also Wednesday, San Francisco re-signed cornerback Eric Wright to a one-year contract. He posted a photo Tuesday on Instagram of his new contract.
Wright had seven tackles and an interception in seven games for San Francisco last season. Wright spent the first half of the season on the reserve/non-football injury list to handle what the team called a personal matter after he signed a one-year contract last August.
Wright had been traded to the 49ers in July for a conditional draft pick in 2014, but he failed his physical, nullifying the deal. Tampa Bay then released Wright.
Shortly after the trade, reports surfaced that Wright had been arrested a week earlier in Los Angeles on an unspecified misdemeanor charge. Baalke said the team was aware of the situation.
Wright was arrested in 2012 on felony DUI charges and was suspended for four games last season by the NFL for violating the performance-enhancing drug policy in his first season with the Bucs. He finished with 37 tackles and one interception in 10 games, all starts.
The 28-year-old Wright, a San Francisco native entering his eighth NFL season, had signed a five-year, $35.3 million contract with Tampa Bay in 2012.
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