you can upgrade your components to 105 or ultegra (older versions {ebay}) and keep the 9 speed setup, this way you dont have to buy the shifter, chain rings, chain or cables. if you wanted a different gearing combination you can get a 9 speed cassette w/higher or lower cog limits. a 10 speed setup may have the same number of teeth on the largest and smallest cog just the steps between them are lower, it wont translate into more speed necessarily.
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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