Rounded allen bolt - tips needed!

Ah well. Least you wont' end up with this...

If you can get the pre-load bolt out - which admittedly is tough when the pinch bolt/s are torqued - you might be able to non-destructively remove the arm with a bearing puller. See Campag Power Torque Removal.

Once off, a pillar drill and tiny drill bits would be the next port of call should all else fail.

You could also try these
http://www.screwfix.com/p/screw-extractor-5-piece-set/18643

Great suggestion Howard!

Hmmm looks like my reply didn't save.

Tell me about the angle grinding scene Howard! That's amazing :D

Also liking the red shoes - any idea what they are?

Vans Chukka Boot Crimson

Sick in bed so can't be bothered to check back so sorry if this is a repost.

If the rounded bolt is a steel alloy (and they usually are) one possibility is to weld on an extension. Any bit of steel would do, preferably something flat so you can get some mole grips on it.

You need to really carefully cover everything around it with thick wet cloth or your alloy and paint work will get severely marked. Any workshop should have experience doing this.

if you have a tiny bit of movement in the seized bolt then thats half the battle won already.

If your epoxy stuff works, do small left and right turns and build up on them to free it off. add loads of plus gas too to help it on the way.

if the epoxy doesn't hold it, try chemical metal. failing that get something welded on or drill the sucker out

Tell me about the angle grinding scene Howard! That's amazing :D

Stock Surly crankset had to be persuaded off my wife's Crosscheck with extreme prejudice after the crank bolt rounded and nobody could be bothered to drill it out. Cartridge BB died in the process - collateral damage. Given it had done about 30,000 kms it was no loss.

Doing the business is Mario and Matty from Soho bikes - the former wielding the tool, the later protecting his face.

@nomoreknees that looks like a bugger, good luck.
I wonder if you could do the heat diiferential thing, maybe heat up the crank around the bolt without heating the bolt. What about screw extractor?