Be aware that not all "road" bars measure 26mm at the clamp. If you've
already found a 25.4 stem that you like for fit purposes, you would be
well advised to also look for a set of cyclocross-specific drop bars,
many of which measure 25.4mm. Another good option would be to look for
31.8mm bars and stem, which is the newer oversize standard that is now
being used for both road and mountain bikes. This would allow you to
pair a mountain stem with a drop bar without compromising the clamping
between the two. Whatever you get, make sure it matches.