It might not happen, especially here in Calgary, but I would argue that 9th ave is backed up only for about an hour, maybe two hours max each morning, and outside that it's mostly an empty freeway. 8th is there, but is very limited in use. We really need a protected cycle lane that traverses downtown and continues east of DT.
6th ave would be good as it cuts through downtown and continues into EV, but ends at the west end of DT (though it could be connected to the river path at the west end) 9th is great because it not only goes through downtown, but it goes all the way straight into Inglewood.