At 18,000 miles my G650 GS needs a chain replacement (red dust coming out of a few links). And I have a few questions. What make chain is a good/best replacement for the OEM chain? I have heard that if the chain is being replaced that the sprockets should be replaced also. But the sprockets on my bike don't show much discernible wear. So should the sprockets still be replaced? And if the sprockets need replacement. What is a good/best make sprocket? What is a good source for the chain and/or sprockets? Thanks Much, S.