Might be worth taking to a local car mechanic and seeing if they can weld something L shaped to what remains of the nut. Hopefully it would be strong enough to take the bolt out. It might cost you a tenner or something, but cheaper than destroying a crankset.
Might be worth taking to a local car mechanic and seeing if they can weld something L shaped to what remains of the nut. Hopefully it would be strong enough to take the bolt out. It might cost you a tenner or something, but cheaper than destroying a crankset.