My son had just finished a 260 mile ride on the freeway. He was cruising down a city street at about 30mph when he felt the bike jerk. He was able to get it off the road before he lost momentum and noticed a bolt under the bike and miscellaneous metal shavings. He saw all the bolt heads for the sprocket were missing and the bolt posts were broken off in the wheel at various depths. Two scenarios. About 40 miles before this happened he took a corner too hot and ran up over a curb. He ended up in a sandy patch and although the bike whipped around some he never dropped it. Could hitting the curb have jarred the bolts loose and then they worked their way out until they came out during the reminder of the trip? Other scenario. He had a rear tire replaced about 600 miles ago, including this trip. He called the HD dealership that did the service and they told him they did not touch the sprocket or bolts when they change a tire. Is there something they could have done to cause the bolts to begin to get loose?