i am building my first singlespeed road bike. the bike (80's nishiki century) was originally an 18 speed, w/3 front chainrings. id like to use only the outer 52t ring. my question is, do spacers exist that will help the front ring line up with the rear cog? if not, what's a good method and what hardware should i use? any help/advice is much obliged. thanks.