Now simplified with a single derailleur cage length, the new 12-speed Shimano ULTEGRA R8150 rear derailleur packs our fastest, most precise shifting into a more approachable option. With our fastest, most accurate shifting, the new 12-speed ULTEGRA R8150 rear derailleur is more versatile than ever thanks to a single cage length option that is compatible with 28-34T low sprockets.