Worrying noise on a VFR 750

[Black Knight]

I've noticed a noise recently when I slow to a stop. I may be present as i'm going but I can't hear it over the engine.

It's hard to describe but its a 'shimmering' noise which I hear when I come to a stop. It goes on for 2 or 3 seconds then stops. Reving the engine doesn't have any affect on the noise.
It almost sounds like ball bearings being rolled around.

Any ideas
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Where does a turn end? 'Where you can do anything with the gas you want to, where you are brave again, where your attention is free from the turn, where you are sure you can do it better next time; that's the end' - Keith Code.