This bike
Untitled by
Stuart Black, on Flickr
is running a 10 speed cassette, 10 speed rear derailer and a 10 speed chain. The crank is a Race Face Turbine with a 94/58 BCD (allows for an easy 20 tooth inner). I'm reasonably certain that the crank is a 9 speed but it may even be an 8. No chain issues.