CB Roubaix upgrade to Shimano Tiagra - brake problems
The measurement that is important here is the caliper reach. As always, there's a great article on Sheldon Brown's website

Reach is the effective length of the arms of a caliper brake. This is measured from the centerline of the center bolt diagonally down to the middle of the brake shoe. Reach is commonly expressed as a range (allowing for the fact that the brake shoes are adjustable, typically 10-15 mm.)
Reach dimensions can run anywhere from 39-108 mm. There has been a historical trend toward shorter-reach brakes, as newer bicycles, particularly racing-style road bikes, are designed for use with narrow tires and without clearance for fenders.

So it sounds like you've purchased brake calipers with the incorrect reach for your bike. You'll either need to put your old brakes back on, or purchase some calipers with the appropriate reach range for your bike.