How do I find a derailer that is compatible with my broken Suntour Arx front derailer?
Maybe someone has a better answer than this, but I would first determine if you need a braze on or clamp front derailleur. If clamp then determine the size by either inspecting the derailleur clamp or measuring the seat tube. Then you need to check if it is top or bottom pull by inspecting if the cable pulls from the bottom or the top to actuate the derailleur. Next you need to determine the size of your big chainring and make sure any fr der. you are looking at accomadate that tooth size. Then you need to make sure the max difference in teeth between the big and small chainring is less than or equal to the tooth difference for any derailleur you are looking at. Once all of this is determined buy a derailleur
Any front derailleur for a double crank (assuming) will work. Make sure it's not braze-on.