On the rear wheel of my 2004 WR450 about 75% of the spokes have come loose. About 200 miles ago a few of the spokes were loose so i tighhtened them up but now most of them are loose. I know the wheel will need to be respoked but does anybody now why this has happened? The bike has done only done about 3500 miles so it seems a bit poor that this has happened. Is this a common problem? Cheers. Lennie.