Ultegra shifters with Tiagra setup?

[Deefex]

I have a Cannondale CAADX Tiagra that I purchased with a C2W scheme, and on the whole I'm very happy with the bike. One thing I'd like to upgrade however, are the Tiagra levers. Compared to my road bike (Cube Agree SL 2011) which runs full Ultegra, the Tiagra levers feel stiff and unwilling whereas the Ultegra shifters are wonderfully light and responsive. A world of difference.

My Cannondale componentry consists of the following:

Shift levers: Tiagra 4600
Cranknset: Omega BB30 46/36
Front Mech: Tiagra 4600, 34.9mm clamp
Rear Mech: Tiagra 4600
Cassette: Tiagra 4600 12-28, 10-Speed

Can anyone confirm whether I could simply swap out the Tiagra levers for something like Ultegra 6770 10-speed levers without having to replace any other components?

I realise that 105 may be a cheaper alternative but I've never used them so can't say how different they may feel from Tiagra.

Thanks in advance

 

[400bhp]

Hmm-not sure that it's the levers that are stiff?

I have tiagra and 105 levers on different bikes and the shift feels the same?

 

[User6179]

Tiagra shifters will work better as the cable is not under bar tape, knackered two left hand ultegra shifters and changed to tiagra and the shifting is better, also have 105 shifters which are stiffer than tiagra.

If the cable goes through the frame at bb make sure its working freely, think the small plastic bit under my bb was slightly misalinged on my my cube agree gtc race 2011.