I recently purchased a new Swissbike LX and feel that the crank needs to be swapped. It has a SR Suntour with 42/34/24 gears. I would ideally like to have something with a 50-54 large gear, I would probably never use any of the other gears on the front sproket, so the others would be of no issue what they are. First of all, could I fit a larger sproket/crank with the current front derailleur? Could someone recommend a decent quality one for under $200 (usd)? I believe that it is a square tapered crank, I attached pictures. I appreciate all help.