Most bridle ways are maintainable by the local council.
The council has no statutory duty to maintain bridleways to a standard that is suitable for bicycles. It only has to maintain them so as to be passable by foot or on horseback.
Restricted byways are dealt with differently. The council has no statutory duty to PROVIDE a surface that’s suitable for vehicles, however, as many of these routes were historically made up to accomodate motorvehicles and/or horse and carts/pedal cycles they do have a duty to keep that surface in repair.
Many restricted byways/BOAT’s are incorrectly recorded as bridlepaths.
Thanks to NERC act the task of having these correctly recorded has been made much harder in practical terms, even at restricted bywyay status.