What exactly do you mean by traditional or oversized?
26mm is the 'traditional' drop bar standard, 31.8 is modern oversized, but cinelli made bars in 26.4 until the 1990s and bars were made in 25.4 as well.
Nitto make a couple of bullhorn bars in 26mm clamp diameter, which is the one you are most likely to need, and the one that most quill ('traditional') road stems will fit. http://www.hubjub.co.uk/nitto/nitto.htm
What exactly do you mean by traditional or oversized?
26mm is the 'traditional' drop bar standard, 31.8 is modern oversized, but cinelli made bars in 26.4 until the 1990s and bars were made in 25.4 as well.
Nitto make a couple of bullhorn bars in 26mm clamp diameter, which is the one you are most likely to need, and the one that most quill ('traditional') road stems will fit.
http://www.hubjub.co.uk/nitto/nitto.htm