Any countries where there's a general speed limit for bicycles?
Many countries have some sort of road rule that says &quot;drive to the conditions&quot;  so you use common sense and best judgement, ie don't drive 100 km/h in fog just because that's what the posted sign says.
I'm not aware of any location in the world that legislates that bicycles must have a speedometer compulsory.
In the UK you can be charged with wanton and furious cycling

Laws that apply to motorists but NOT cyclists… 
Speeding offences Because bikes aren’t fitted with speedometers, cyclists can’t be charged with speeding offences. HOWEVER, if they are considered to be going too fast for the conditions, they could be charges with ‘wanton or furious cycling’ which is a criminal offence under section 35 of the Offences Against the Persons Act 1861 (as amended by the Criminal Justice Act 1948 s1(2))

From https://www.roadlawbarristers.co.uk/wanton-and-furious-cycling-a-guide-to-the-road-traffic-laws-that-apply-to-cyclists/
(this is a short but interesting read too)