I thought at first this was maybe a 24" wheeled bike, but appears to be full size. Why would you want to go to 53 teeth and give up the lower gears on top of that. Even someone who's a Cat II racer would be fine with a 50-11 or 50-12 top gear. In fact I raced Cat III crit's back in the 70's/80's and never had more than a 48/13.