I find it is safer to pass the bus on the left if there is no traffic and the bus seems to be stopped for some time. I have seen buses stopped for 5 to 10 minutes before and I refuse to wait for them in this situation. If it appears that the bus will be stopped for just a few seconds I will wait. In some areas I find I can outrun the bus, especially in congested areas. In other areas the Bus averages 25 mph and I just let it go. I think it depends on the situation. My main rule is don't get in a rush. I find when I am rushing is when I am in the most danger, on bike or in car.