A bicycle hub gearbox comprises a first planetary gear mechanism and a second planetary gear mechanism and a tubular linking member. The second planetary gear mechanism is operatively coupled with the first planetary gear mechanism. The tubular linking member include a first toothed ring part engaged with the first planetary gear mechanism at a first axial region and a second toothed ring part engaged with the second planetary gear mechanism at a second axial region such that a permanent synchronization between the at least two planetary gear mechanisms is achieved. The first and second toothed ring parts have different diameters and being axially spaced apart.