The Shimano Altus rear derailleur features an advanced light-action, long-cage design with Teflon-coated bushings. What sets the Shimano Altus derailleur apart from other rear derailleurs is its unique 13 tooth upper and 15 tooth lower pulleys that provide a 43 teeth chain wrap capacity (more than conventional 11 tooth pulleys) and enable them to rotate with less friction.
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