Shimano Tiagra 4700 10-Speed Rear Derailleur Close to Shimano 105 in build quality, Tiagra is a reliable, smooth shifting rear mech made for Shimano 2x10 or 3x10 road bike drivetrains. Available in two styles: SS short cage and GS long cage Shimano recommend the SS short cage version for 2x10 double chainsets where the largest rear cog size is 28t Shimano recommend the GS long cage version for 2x10 double chainsets where the largest rear cog size is 34t and for triple chainsets where the largest rear cog size is 32t Wide link design increases rigidity and service life Advanced light action for low-friction shifting up or down the cassett Alloy body and outer link for lower weight without compromising strength and durability 11-tooth pulley wheels reduce pulley wear and chain noise Two fluorine-coated link pin bushings for low-friction performance 'Offering pro-level features, the 10-speed compatible Tiagra rear derailleur gives high performance at a low price.' Shimano. Shimano Tiagra Half way up the Shimano hierarchy, the Tiagra rear mech benefits from being fundamentally similar in shape, profile and technology to a Shimano top-end Dura-Ace/Ultegra mech - albeit using less exotic and less lightweight materials - while being noticeably more sophisticated and built to finer tolerances than a Shimano entry-level Tourney mech. This Tiagra mech is a perfect example of why mid-range Shimano is almost always a best buy in cycle components.