Essential purchases for any frame, carrying a replacement rear mech hanger can make the difference between a quick road or trail-side fix and a very long walk home. Not just the preserve of rock-smashing mountain bikers, snapping a mech hanger is within the capabilities of any cyclist. Often made of lightweight cast alloy that is designed to snap (rather than putting your much more expensive rear mech in danger); broken mech hangers can result from badly adjusted gears, sticky freehubs and entanglements with foreign objects, amongst many other "I was just riding along mate" excuses. So, whether you choose a genuine replacement or a superior CNC upgrade, just go and buy a replacement mech hanger. Now.