I was riding my 2007 Specialized Roubaix Triple (alloy mainframe) on a century ride two days ago when I starting hearing a sharp dink sound near the bottom bracket with every hard jolt (there were many). I checked around for frame cracks, saw none.
Later, I developed an additional ping on every pedal stroke.
On a 50-miler the following day, the sound turned to three or four pings or ticks on each pedal stroke.
Afterward, when I put it on a workstand, I couldn't duplicate the rough sound, and the crank turned smoothly.
There's no play when I lever the cranks. The pedals spin cleanly.
I don't mind changing the BB, but how can I tell whether that's actually the problem?
Thanks.

Maybe it's a spoke, more likely a rear.

It's very common not to duplicate bottom bracket or stress related sounds on the stand - not enough stress. Very unlikely to be a spoke, as the wheels turn at a different rate than the cranks. How to test? Here's a start: Creaks, Clicks & Clunks. The one thing I would add that Sheldon's page leaves out is that sometimes contamination between mating parts can cause a problem, such as rust scale on the spindle flats or where the pedals meet the crank arm faces, or even grit under chainwheel bolts. It's always good practice to clean off both mating surfaces. I use a fine steel wool and then a rag.

You'll have an easier time diagnosing sounds by adopting a methodical approach, and referring to Sheldon's page rather than scrolling through a bunch of "this happened to me" posts.

All the bottom brackets I have replaced were bad from wear. They were "loose" but didnt make noise. Your problem may actually be from the crank arms.

-SP

Or the chain ring bolts. Andy.

I tightened a crank bolt too much once and got a sharp (but not loud) ping when I pedaled hard enough. It took me a long while to figure it out. Fortunately I hadn't done permanent damage; taking the crank arms off and putting them back on, careful not to over-tighten, eliminated the ping.

The best way to test any part is to replace it. I keep an old one that's probably still good around. Even an old one that's not good, but doesn't have the same symptom, can be used to test.

A actual ping indicates something on the bike is not clearing everything. Douple check how everything is mounted put on the bike.

Does it make the sound when standing as well as sitting? The increasing number of pings sounds like a seatpost creak. I'd pull the seatpost, clean it, grease and re-install. It's amazing how every sound a bike makes sounds like its coming from the bottom bracket.

Yes, the sounds continue whether pedaling hard or lightly, standing or sitting -- not when coasting.
Thanks for the suggestions of crank arms and chain ring bolts.
I'll investigate those.

Hi! may sound stupid, do you hear anything when you stop pedaling?