Enduro 2 is made for MTB and as there are no 31.8 handlebars in MTB world it was never expected to be used on road bikes, although you'd have no problem to get it to work on regular-sized bars... But call Cateye they are really pretty helpful...

Also, the Cateye Mity 8 has same functions as your Enduro and you can get it for $15.00 but I'd go with Astrale 8, as it has cadence, which is pretty useful in road cycling... Also, get a one with rear speed sensor, if you ever plan to use your bike on a trainer... You'll thank me later...