[kJackd]

520?

525?

 

[DUCMONROB]

525!

 

[Bing]

I spoke with Chain Gang (sprocket/chain specialists in Australia) and they recommend the 525 for every Duke unless you're racing and like replacing chains more often. I've had their sprockets and an 525 RK X-ring chain for over 4000kms and it hasn't need adjusting yet.