A twin clutch hub, comprising: a hub casing, which is rotatably supported on and around a wheel axle and characterized in that the hub casing has an end surface that is recessed to form a socket that receives and retains therein a pawl member; a clutch shaft, which is rotatably fit around and has an end received in and fixed to an inner circumferencial surface of the hub casing and an opposite end over which a one-way roller clutch is fit; and a chain wheel seat, which has an end forming a mounting section to which a toothed wheel is mounted, the chain wheel seat having an inner circumferential surface fitting over and fixed to the one-way roller clutch in such a way that the toothed wheel is engageable by the pawl member to collectively serve as a ratchet to form a complete ratchet wheel, wherein the chain wheel seat is directly coupled to the hub casing by the one-way roller clutch that transmits bicycle power from the chain wheel seat to the hub casing and the chain wheel seat is also directly coupled to the hub casing by the ratchet wheel that is formed of the engagement between the pawl member and the toothed wheel, wherein transmission of bicycle power is achievable such that when an angle of elastic deformation of the one-way roller clutch is smaller than or equal to a backlash of the ratchet wheel, with a returning side tooth backlash being zero, the chain wheel seat transmits the bicycle power through the one-way roller clutch, and, alternatively, when the angle of elastic deformation of the one-way roller clutch is greater than or equal to the backlash of the ratchet wheel, with a returning side tooth backlash being zero, the chain wheel seat transmits the bicycle power through a combination of the one-way roller clutch and the ratchet wheel. a hub casing, which is rotatably supported on and around a wheel axle and characterized in that the hub casing has an end surface that is recessed to form a socket that receives and retains therein a pawl member; a clutch shaft, which is rotatably fit around and has an end received in and fixed to an inner circumferencial surface of the hub casing and an opposite end over which a one-way roller clutch is fit; and a chain wheel seat, which has an end forming a mounting section to which a toothed wheel is mounted, the chain wheel seat having an inner circumferential surface fitting over and fixed to the one-way roller clutch in such a way that the toothed wheel is engageable by the pawl member to collectively serve as a ratchet to form a complete ratchet wheel, wherein the chain wheel seat is directly coupled to the hub casing by the one-way roller clutch that transmits bicycle power from the chain wheel seat to the hub casing and the chain wheel seat is also directly coupled to the hub casing by the ratchet wheel that is formed of the engagement between the pawl member and the toothed wheel, wherein transmission of bicycle power is achievable such that when an angle of elastic deformation of the one-way roller clutch is smaller than or equal to a backlash of the ratchet wheel, with a returning side tooth backlash being zero, the chain wheel seat transmits the bicycle power through the one-way roller clutch, and, alternatively, when the angle of elastic deformation of the one-way roller clutch is greater than or equal to the backlash of the ratchet wheel, with a returning side tooth backlash being zero, the chain wheel seat transmits the bicycle power through a combination of the one-way roller clutch and the ratchet wheel.