| Shane, I think your bike is the same primary drive as mine as I was running 14/40 at Cadwell this year and was about 8500rpm at the end of the Park straight.
Based on the gearing at Donnington I will probably start the first few sessions for the Friday at that then as I hopefully start to carry more corner speed I may drop the rear to 39.
Ultimately your riding style, corner speed etc will determine the best gearing for you! | 
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