Shimano shifter/brake upgrade

andyboyce Posts: 156
edited October 2012 in Road buying advice
I have a Specialized Roubaix Compact 2012 model with 10 speed Tiagra and I am looking to upgrade the shifters and front and rear mechs to Ultegra.

There seem to be some good deals on ebay and I found some Shimano Ultegra ST6600 SL STI 10sp Brake & Shift Levers (Double) listed.

Will these be compatible with my existing Tiagra until I upgrade the rest ?