Pushing the top of each wheel to check if they bouncing abnormally. IF not, the shocks are still in good shape. How long have the tires live? For a long time used tire, even the tread looks good the tire surface could become hard and cause noise and unconfort. If you ever experience low profile tire compared with high profile tire, you can tell how much the tire contributes to ride comfort.
Why not look into the tires first.

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