This says that A123 cells have a 30C discharge C rating which is awesome so yeah you should be able to run your bike off of one pack. As long as the BMS circuit board on the pack allows that kind of a discharge current. This says 30C rating for A123 cells. So if it's 30C then each 36v2.5AH pack should be capable of about 60 amps discharge current, definitely above the needed 20 amp of your controller or whatever you are using.

http://www.flyelectric.ukgateway.net/lithium-a123.htm