Campagnolo chainring bolt stuck to crank I have a Campagnolo 11 speed Athena setup. I am enjoying a noisy creak which I suspect is located in my chainring bolts. I have replaced all of them, except  the one that screws the chainring to the crank. That one is stuck. I tried to unfasten it, but I messed up the bolt. My hex key can not grip it now.

Do you have any ideas on how to solve this?
I would underscore taking it to a trusted local shop to remove the bunged screw.

But I would also suggest that if you've tightened the other four that your creak is NOT coming from the chain rings but probably from either your pedal, your cleat or your shoe. Also if you haven't lubed the chain for awhile you can try that as well. 

A creak from the chainrings will almost always be heard when pedaling on both sides. This will also be the case with the crank bolt as well if it isn't properly torqued. 

In one case it was the right LEVER that wasn't tight enough. In another the front derailleur. But shoes and cleats are the most common.