The Irish rockers are preparing to head out for a world tour, but the singer still can't play guitar following major surgery on his fractured arm in November (14) after he fell off a bike in New York City's Central Park.

He tells the New York Times, "I really used to think that my head was harder than any surface it came in contact with, and I don't anymore. I didn't come off a Harley-Davidson. I came off a push bike and smashed myself to bits. There is no glory here... It feels like I have somebody else's hand... I can't bend these (fingers), and this (my hand) is like rigor mortis. But they say that nerves heal about a millimeter a week, so in about 13 months I should know if it's coming back... It's all numb here (forearm and elbow)... The shoulder's better, the face is better... But this (hand) is the hard bit because I can't play guitar."

U2's tour kicks off in Canada on 14 May (15).