Unless your LBS has one that they have taken off a bike and held on to it, I have never seen a crankset sold without the chainrings commercially. I tried looking for a Tiagra crankset for my old Defy after one of my LBS stripped the pedal threads in the drive side crank. The bike came with an FSA crankset, which I didn't like, and had the same BCD and bolt pattern as the Tiagra. Couldn't find one anywhere and ended up buying a complete, with chainrings, crankset.
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HCFR Cycling Team
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2017 Colnago C-RS
2012 Colnago Ace
2010 Giant Cypress