My Tiagra equipped Trek was Flitedeck compatible... it should say something to that effect on the shifters themselves, I do believe.

OTOH, if all you want is cadence, there's cheaper solutions. The whole flitedeck setup is a little pricey, around $80-90 or so.

You can do better, for less. For example, the Catey Strada wirelss with wired cadence is $38:
http://www.lickbike.com/productpage....9;3207-07'