As Kontact and Russ Roth said, you can shim the steerer tube from 1" to 1.125". I had to do that with a CAAD4 project bike:

Bike Forums - View Single Post - sci guy's & SmellyAir's CAAD4 Bike Build Bromance

I used a seat post shim as I prefer to shim the entire exposed length of the steerer, not just the section clamped by the stem, so I can use 1.125" spacers instead of 1" spacers under the stem.

Amazon.com: Thinvik 60MM Bike Seat Post Shim 22.2mm, 25.4mm, 27.2mm to 25.4mm,27.2mm,28.6mm,30.4mm,30.8mm,31.6mm Bicycle Seatpost Tube Adapter-25.4mm Shim to 28.6mm : Everything Else

If the 60 mm length works for you, make sure you order the 25.4 mm to 28.6 mm version.

As noted by Russ Roth and in my post linked above, you have to get a wider top cap.