creaking handlebars

My handle bars creak/click when climbing out of the saddle. I've tightened up the clamp bolts, tightened the stem clamp to the steerer and it still happens. Could this be because they're too tight? Any other ideas? I'm sure it's the handlebars as it doesn't happen when seated.

Could be other things still – but take the bars off and check them very very carefully for cracks.

could be BB, headset, pedals

apply a thin smear of grease under the contact points of stem/steerer/bars.

i recently had a similar problem… creaking when climbing out of the saddle

turned out to be the front wheel mavic bearings and not the bar/stem at all.. check for play in the front wheel

Is there a torque specified on the stem? Mine clicked when the bolts were done up too tight.
Removed, regreased and torqued them up correctly.

Strip the stem off that part fo the forks that I've just gone completely blank on, oh yes steerer. Bloody hell my memory/brain.
Take face plate off stem and remove bar. Clean all areas that meet thoroughly, maybe with disk brake cleaner or other solvent if you have it (acetone/iso-propyl alcohol etc). Reassemble and give it a whirl. Anywhere else I'd go for grease/copperslip but don't sound good in these areas. If still creaking try a dab of thread lock in a few places round the interface and see if that helps. Used to work on a Coda crank I used to have. For a while at least.

As stated above, have a good look for cracks. maybe replace the bolts incase they have gone slack, though TBH it would probably more likely be the female part of the stem that would go slack being in ally as opposed to some form of steel for the bolts. New ones may help though.

Another thought is it may be the steerer/fork crown joint? Can you swap stem/bars with a mate? If so does the creak go with the bars/stem or stay on your bike?

may just be one of those situations when it is tiny "events" in a lot of parts adding up to the creak.

strip down, grease bolts and reassemble it is then.