The only sound I can think of that would have been affected by the BB failure and then replacement would be front deraileur rub. Does the noise happen no matter which gear you are in?
The description of the sound however makes me think the tire rubbing the frame is the most likely cause. You might want to check the tension on your wheels, not just for trueness, but make sure the spokes have not loosened up enough that a wheel can flex enough to rub during climbing.
When diagnosing these sort of problems you need to pay attention to all the clues. You've caught a few of them, like only during pedaling, and worse under greater loads. Here's some other things to consider:
A problem with your cogs will produce rapid clicking noises at even intervals that don't match a particular position on the crank. A problem with the crank or pedals will produce a clicking noise that usually lines up with a particular location on the crank. Chain problems, if they only affect a few links will have a less frequent noise pattern and will have pauses in between the noise as the "bad" chain travels over sections where it is not in contact with another surface or usually traveling through the rear deraileur, where it is pivoting the most.
Because of the pause in your noise, I'd consider the chains as a possible cause.
I don't think that listening for the noise while pedaling in a work stand is likely to work because the noise seems to be related to how much force is on the the drive train, however you might be able to get the noise to occur at much slower speeds by applying a brake. You could then have someone else listen for the noise.
Last edited by Possum Roadkill; 05-16-08 at 09:04 AM.