I’ve managed to round out the 2mm hex head screw on a derailleur hanger. Try as I might I don’t seem to be able to unscrew/remove the screw. Any ideas/pragmatic suggestions from the Singltrack hive?

Not sure why they use 2mm hex fittings for this or any other location on bikes!!

Cheap torx bit.
Hammer.

Forgot to mention that the hex head is countersunk so unable to saw across to use flat bladed screwdriver, etc.!

When you say “hammer” do you mean hammer drill?

Hammer the cheap disposable torx bit into the mangled mess and undo.
Socket ratchet will allow you to gently add the force to undo.

As above, also try applying heat if you have no luck.

Thanks for the replies and advice. Panic over; I used the hex key from my trusty old Leatherman and I managed to shift it! New screws will be ordered!

Many thanks all.