How do I know if a given hardtail mtbMTB frame is supposed to have suspension forks? I read somewhere that if you want to convert a suspension bike to a rigid you need 'suspension corrected' forks which are longer. So I assume there are different types of frames based on if the forks are supposed to be rigid from the start and another design that is meant for suspension forks (?). If that is true, assuming that I can't measure the slack angle of the frame, how do I know if the frame is designed for suspension forks or not?