Actual speed limits don’t apply to normal bikes, as there is no requirement for a speedo to be fitted.
I would imagine they do apply to a bike is fitted with a speedo though, I could be wrong of course.
If the bike is an s-pedelec (a de-restricted-bike, electric moped, whatever you want to call it), then the posted speed limits apply and the bike is supposed to have a working speedo (in the same way that a moped, scooter, motorbike etc would have).
If it’s a regular e-bike (one where the motor cuts out at 15.5mph), or a normal (analogue?) bike, then speed limits do not apply because it’s not classifed as a vehicle, it’s a bicycle.
A normal bike fitted with a speedo (any GPS for example) – the speed limits still don’t apply, the only thing you can be done for is the reckless cycling or whatever law it was they got Charlie Alliston convicted with.
That reporting is atrocious, it’s very confused about what the speed limit actually was, whether the rider had got the bike to that speed using leg-power alone or if it was under “throttle” to achieve that speed or what.