I f you ride a track frame with a tight clearance between the rear wheel and seat tube and have problems getting your chain tension right. when your at a bar steal or ask for a stack of beer coasters and when you get your chain tensioned just how you like, take said coasters and make a stack that fits inbetween the tire and seat tube. then everytime you change a tire or need to adjust the tension on your chain you have a handy guide and do not have to walk the rim back and forth and it takes just 2 seconds.