the crj200 pit is about 10 ft deep, 7 ft wide, about 4ft high, and the door is freakin' small. i wouldn't freak out over two bikes missing service, but i wouldn't be suprised if mail or cargo got priority; especially if this is a mid-day or evening flight.
True, the door is small (about 4' high x 3' wide). Your other dimensions are relatively close, with the exception of the height of the pit. It's actually close to 6' high.
If the bikes are packed in a protective shell, there might be some issues in getting them through the door (too wide, if memory serves, and tilting on an angle would be limited due to the position of the #1 engine unless they removed the belt loader and lifted the box up from the ground), but they may be able to get them on. If they're sent out to the aircraft as is, it shouldn't be an issue.
Enjoy your trip, Altaflyer!