+1 screw extractors. Great on large bolts (6mm plus) but near hopeless on smaller ones. My lbs got a stripped hex out of a vitus by soldering a long handle 4mm Allen key into the stripped hole. I've also seen this done successfully with a welding joint on stuck pedals into cranks you have to cut the bulk of the pedal off to leave a stub of the spindle, weld a steel bar onto it at 90 degrees and bosh, it's off. It's all about leverage innit!!
+1 screw extractors. Great on large bolts (6mm plus) but near hopeless on smaller ones. My lbs got a stripped hex out of a vitus by soldering a long handle 4mm Allen key into the stripped hole. I've also seen this done successfully with a welding joint on stuck pedals into cranks you have to cut the bulk of the pedal off to leave a stub of the spindle, weld a steel bar onto it at 90 degrees and bosh, it's off. It's all about leverage innit!!