Sportworks is one of the pre-dominant manufacturers of transit bus bike racks in the United States. The specifications for their racks are contained on their website:
https://www.sportworks.com/products/transit-bike-racks


Glancing through the specs, it appears they are designed for a 55 lb bike:

"The bicycle rack shall secure bicycles up to 55 lbs. per wheel tray
while the vehicle is moving. Additionally, the bicycle rack shall
support a 250 pound (maximum) centrally located static load
when it is deployed and the vehicle is not moving."