I struggle to imagine how they will possibly enforce this
"They" being the operative word.
TfL cannot enforce, as they do not have the authority to issue PCNs to cyclists (or owners / keepers of pedal cycles), as they can only do so via approved devices, i.e. cameras, which cannot, as yet, identify cyclists.
And even if they could identify the cyclist via camera, they only have the authority to issue PCNs to keepers of vehicles.
The police will not (and, as far as I recall, cannot) enforce as the roads are, by and large, the domain of TfL, and governed by the Traffic Management Act, not the Road Traffic Act.
But the polis might still give a cyclist a £30 NEFPN, though I don't know for which offence.
TfL cannot enforce, as they do not have the authority to issue PCNs to cyclists (or owners / keepers of pedal cycles), as they can only do so via approved devices, i.e. cameras, which cannot, as yet, identify cyclists.
And even if they could identify the cyclist via camera, they only have the authority to issue PCNs to keepers of vehicles.
The police will not (and, as far as I recall, cannot) enforce as the roads are, by and large, the domain of TfL, and governed by the Traffic Management Act, not the Road Traffic Act.
But the polis might still give a cyclist a £30 NEFPN, though I don't know for which offence.