Yes you can use a 9 or 10 speed crankset with a 8 speed cassette. the thickness of chains has changed with more gears skinnier so as long as your current chain meshes right your all set
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2010 Kestrel RT900SL, 800k carbon, chorus/record, speedplay, zonda
2000 litespeed Unicoi Ti, XTR,XT, Campy crank, time atac, carbon forks