From the website conditions of carriage.
Bicycles other than foldable bikes are not allowed on our vehicles apart from certain vehicles on specific routes which have a specifically built bike trailer in which case bicycles must be stored in such trailers as directed. Foldable bikes must be securely folded and stored in the designated luggage area of the vehicle so that they are stable and do not cause any obstruction.
During travel, buggies, prams and pushchairs must be securely positioned so that they are stable and do not cause an obstruction or obstruct the aisle. At the drivers discretion, there may be times when a pushchair, buggy or foldable bike will not be allowed to board due to insufficient space being available. This is for your health and safety.
Years ago we used to have a bike trailer for the Brecon Beacons bike bus but funding was stopped.