finding where the noise comes from
 

Ok straight to the problem, i suspect that a clicking-creacking noise comes from the chain at the chainrings, is that possible? it is not strong but i hear it on every pedal stroke except when i climb hills under heavy load it seems to not make noise. i think its not my bottom bracket as it has not play at all and cups seem tight, front derailleur is not rubbing on chain, i almost thought there was the spokes of my back wheel and i tighten them.
my bb is hollowtech 2 ultegra 6600, the chain seems moderate or more wear so i will change it very soon, the chai rings show little wear but lots of life left (didnt even started to show any shark fin) and they are completely straight.

only other clue is that the frame is steel( not any damage anywhere) but may it be flexing so much? only pedals left to check but they seem ok, any suggestions? Is it the chain you think?
sorry for my bad english

Check the pedals. It is simple to swap in another pair, preferably platform type to eliminate shoe/cleat noise. Thoroughly clean and grease the pedal/crank interface and torque them correctly (this in itself may fix the problem, dirt at the interface can cause clicking and the like). Do the easy/free things first.

Check your chain ring bolts/nuts, too. Do you ever lube your chain? Consider changing your "moderately or more" worn chain.

I am often surprised when troubleshooting that some dumb, simple thing I think it cannot possibly be, is actually the problem.

ok i changed the chain cleaned the crankset and i noticed very little play in bb, the cups are really tight fitted so i tightened the preload bolt till the play is gone but it still make the same creaking noise but a bit less, i tightened more but nothing, the crankset moves fine without play.
Is there any problem with the bb?

+1, ALWAYS check the pedals first. They're a common cause of this kind of issue, but more importantly are so easy to rule in or out, that you'll feel like an idiot if you chase all over the bike and find this problem last. So call it "feeling dumb" insurance.

BTW- you can check with a spare set of pedals, preferably something simple in case it's a cleat issue. Or you can often solve it by removing the pedals, cleaning the threads and mating faces on both pedals and cranks, then greasing and assembling.

Hmm since the first reply on this post , i changed the pedals to new one and i forgot to mention it. The noise come clearly from the bb as tightening the arm a little reduces the creaking but tightening it more akes no difference.
So im asking if the bb will need replacemwnt soon.