The 25-year-old shot-stopper was City's first choice until the summer when James arrived on a free transfer but has only made one appearance this season, a League Cup tie against Southend in August.
Gerken told the Bristol Evening Post: "This last few months is the first time in my career I've been a number two goalkeeper. It has been a learning curve and quite difficult in many ways.
"I still find it hard every Friday when the team is announced and I'm not in it. I still try my hardest in training, whether I'm trying to displace David James or any other goalkeeper. Psychologically, it can be difficult because you train as hard as you can all week and then you don't get the reward of playing on Saturday.
"I still want to be Bristol City's number one goalkeeper and I won't stop trying until the day I leave the club. There is no point being at any club if you don't believe you are good enough to play or haven't got anything to offer the team.
"I think I have a great chance to play, whether it be towards the end of this season or next year. Now I've made the decision to sign a new deal, I am really happy and positive about it."
Source: PA
Source: PA