Every full rotation I feel a small clunk. Only in harder gears, if I'm pedaling easy I don't feel anything. Freshly greased b/b bearings, spin nice and smooth. I think the problem might be the chain. I used an old chain, the links all swivel but not smoothly. I do have a new chain ordered. So what do you guys think, the chain? I really don't want to remove the b/b plus I really don't think that's the problem.

Might be the adjustment on the BB cups. May need to make it just a hair more snug.

If it was a chain with a stiff link, it would be more like every 3 revolutions. Also the clunk would happen at different times depending on which cog you were on in the front. Even if there were evenly spaced stiff links, the clunk would be different depending on the gearing.

If the BB is OK, then I'd look at the pedals, crank arms, and seat.

Is the clunk in the same spot? So if you have it on the stand it clunks where the arms are in the same position?

Inquiring minds want to know. I have a noise too. Took be apart 2 times.

Same spot every rotation while pedaling. I can't get it to do it in the stand.

Do you feel it more in one foot than another?

What position (like on a clock) is the driveside crankarm when you feel it?

6 on the drive side.

Same here- I have a klunk that is only in one or two gears... sometimes.

Of course, I picture my bike suddenly falling apart like the Bluesmobile.

Check that you don't have a loose chainring bolt sticking out and hitting the chainstay. And check both the BB spindle isn't loose in the cups, but also that each arm is tight to the spindle. Is the drive side crank arm hitting the FD?

Also pedals can creak or pop. Drop a spot of oil on them or swap them to eliminate that possibility.

Hmm, a noise when the drive arm is at the bottom, only under torque load, means it is likely to be on the non-drive side because you are just starting to apply torque to that left arm. I always switch out pedals during this exercise because one time my noise was a bad pedal. But if not that, then I agree with others that it almost has to be in the BB or the arm to spindle connection.

Did you grease the spindle bolts before installing the crank arms? Are both arms tight enough? I've had this a couple of times. I was blaming a pedal before realizing one of the crank arms was loose.

'clunks' are classic loose fixed cups

Had that once when the non-drive side crankarm loosened.

Did you regrease the BB or someone else? I suspect a bearing/cup issue.

Drivetrain noises and "feels" can be fussy to find. You could have a pedal bearing that would closely relate to a BB prob. If you have a spare set, swap them and compare.

I just redone the whole bottom bracket. Fixed cup was tight, nice packed bearings, proper tightness of spindle, pedals ok, and chainring bolts tight. I'll take it out tomorrow and see how it does. Thanks.

...or the Wonderful One Hoss Shay

Do you have panniers on it? I had an issue with heel strike that took me a long time to figure out.

Nope, I took it for a quick ride and I think I fixed it. Still not sure what it was, but I redid the b/b. I'll know for sure when I take a longer ride tomorrow. It wasn't a clunk I could hear, I could only feel it.

I had a bike that had this exact same problem. Clicking noise from the chain only under load once every full turn. It turned out to be the chain. The chain on the bike had shorter links than a regular bike chain, I never bothered trying to figure out what kind of chain it was but it was easy to see the difference when you held the proper chain up against the chain on the bike.

Is there a kickstand in the way?

I recently had this problem... Not the cranks, pedals, hub (possible broken axle?) ...
It was the freewheel! The body had a bit of play....(Regina G.S.C.) exchanged it, came back!
Went to a Suntour freewheel... Alas no more full Italian... Problem gone!

Noise and feedback were highest under full load.

I have yet to take the freewheel bodies apart to review the condition of the pawl's.

I have a noise like a tick, rather than a cluck, at the same location on the rotation on all rings (3). I gave up after:
Changing the BB
Making sure the cranks were torqued to spec.
Changed pedals
Replaced chain
Checked ring bolts
Made sure the pump didn't touch the left crank
Checked FD positioning
Inspected teeth on the rings.
Changing the saddle
Checking the handlebar and stem bolt torques
Checking HS (Threadless)
Checking the frame for cracks, visually
Changing the rear block.

Some times it is there and sometimes not. When it sounds off, it is under heavier load than just cruising.