The injury-plagued midfielder is hoping to revive his career at City after being released by rivals Manchester United in the summer.
The 30-year-old has signed a one-year deal at the Etihad Stadium but, after being restricted to just four appearances in the last three seasons, accepts he is short of match fitness.
That means a return to action against former club Bayern Munich in the Champions League later this month is unlikely.
Hargreaves told the club's website: "It's important that you get back into a rhythm of playing football, and I haven't done that for a while.
"There's tons of games to come this season in various competitions.
"I've never not played in the Champions League. It's pretty much been standard for me every season.
"Bayern is a wonderful club - I had a great time there and won the Champions League.
"They are going to be tough opposition and it will be an exciting game for the club."
Calgary-born Hargreaves made his name with Bayern and shone in the 2006 World Cup for England before joining United in an £18million deal the following year.
He had attracted interest from West Brom after United opted not to renew his contract but feels joining City, expected to mount a serious Barclays Premier League title bid this season, is a greater challenge.
Hargreaves, aware competition for places will be fierce, added: "I like to measure myself agains the best and I've always taken on challenges - I left Canada for Germany as a kid, I've left comfortable situations.
"It's a fantastic group of players here, and I hope that I'll be a good addition to these guys to help out.
"I've lived in Manchester for four years and this move just fits. You've got to trust your instincts."