Yes, bearings WILL cause a sound that sounds like they are hitting each other - because that's what they are doing. If the hub is slightly loose and the lubrication light or loose due to contamination they will shift backand forth. Almost every case I have seen has been a bearing with grease broken down by water contamination, and I saw many do this in my career.
Last edited by cny-bikeman; 06-25-10 at 06:21 AM.