optional Ari cog compatible with Shimano XT M8000 11/40 and 11/42 11speed cassetteto obtain a more fluent scale, with 44T, 45T and 46T upgrade, Aribike offers you the optional 18T cog which substitute 17T and 19T cogsreplacement is easy and fast - see video attachedmaterial used is chrome steelthis cog can't be sold separatelypurchase must match Aribike 44T, 45T or 46T cogs
ARI spare cog 18T for Shimano XT M8000 11/40 and 11/42 11speed cassette