I measured the distance across the frame from edge to edge of the cylinder that houses the BB. I got the equivalent of 73mm. I'm not sure about that second measurement though. When I looked up the replacement, I got choices of 73 x 113, 73 x 118, 73 x 122. My guess is that number is the length of the axle that the cranks are mounted to. If so, mine was 2 mm off from any choice I found. I believe mine measured 4 11/16. Do I go greater or lesser in length? I have the Diamondback Edgewood. I'm going with the Shimano BB-UN55. I'm also replacing the crankset and installing a Shimano CS.

Sorry, but I don't know all of the bike parts' names yet.