Shimano rm66 rear hubthe shimano rm66 rear hub is an affordable alloy disc brake compatible quick release hub this entry level mountain biketrekking hub is great for training runs casual trail riding or for use on a commuting bike made from a mix of steel and aluminium for strength lightweight and durability this rear hub is also strong and smooth due to shimanos use of their cup and cone bearing technology featuresmaterial aluminium body steel main axleaxle type quick releaseov