Shimano RD-TY300 6/7-Speed Rear Derailleur ensures reliable and quiet shifting and handles a wide range of gearing for reliable rides. This rear derailleur features SIS rear indexing and a double servo-panta mechanism for smooth shifting. Its SGS cage handles wide-range gearing up to 34T, while 13-tooth pulleys boost durability. The light-action design makes long rides easier and more comfortable. Buy your bike gears at Halfords, the UK's largest bike accessories retailer.