By Brad Quartuccio
Drivetrain wear is inevitable. Much like tires the drivetrain bits that make everything go ‘round are ultimately disposable pieces. Wearing out chainrings just happens, largely in relation to number miles logged and what kind of grit you find yourself riding through. There are a number of other factors that influence the ultimate life of the ring—original manufacturing quality, gear choices, maintenance etc—but the actual method of wear is pretty much the same, and goes hand in hand with a worn chain.
With a new drivetrain, the chain and rings match up perfectly, with each chain roller fitting tightly and completely between each tooth. As the chain and chainring wear, the rollers are forced incrementally further up the face of the tooth, eventually wearing them into a distinctive shark-fin shape. The extent of the wear is many times not evident until a new chain or ring is installed, and skips under load. The new piece doesn’t match with the old, and may signal that the whole drivetrain requires replacement.
Besides keeping everything clean and lubed, the best way to protect yourself from pricey replacement chainrings and cassettes is to replace your chain regularly, before it is “stretched” from wear.