Rule 124 of the Highway Code sets limits for various vehicles, which MUST be complied with. Bicycles are not included. While you can’t normally be charged for speeding on a bicycle you could, in extreme cases, be charged with careless cycling (maximum fine £1,000) or dangerous cycling (max fine £2,500). Furthermore, local bye-laws can impose limits on cyclists. Bournemouth’s promenade, for example, has a speed limit of 10mph (and on some days bikes aren’t allowed there at all).

Frankly, I'd quite like to be in sufficiently good enough physical shape to exceed even the 20 mph limit on my bike. But those days are gone....

Dave
Blue 4/4 1969, Green +4 1953, (different) Green +8 1977