Sram X4 rear derailleur, 7/8/9 sp, 1:1 cable pull ratio, medium cage. Note medium cage gives better ground clearance than long cage on smaller bikes, and is essential on Beinn 20.

Before ordering this item because you believe your current one is bent (eg, as a result of a fall), check that it is not the "derailleur hanger" that is bent, which is more likely. See our range of replacement hangers below.