Should i upgrade from Skultura 400D with 105 to giant tcr advanced with ultegra di2? I have had the merida skultura 400d and have ridden around 1100kms. Would there be any value in getting giant tcr advanced pro disc or the propel advanced pro? My rides are generally 80kms a week usually by myself at an average of 23kms per hour with average cadence of 65. Would an aero bike make a difference? Or would i be better in getting aero wheels on my skultura?

Many thanks
Sandeep
My rides are generally 80kms a week usually by myself at an average of 23kms per hour with average cadence of 65. Would an aero bike make a difference?


For the type of riding you are doing, aero bike will make a small difference, one that you are likely not to notice very much.  Aero bikes do however have a much stiffer ride, so you will likely find the bike to be less comfortable over longer distances. For casual riding, the "endurance" focused models will likely be a better match as these have typically more comfortable positioning and frames that provide more vertical compliance to dull road vibration.  The models you were mentioning are focused only on racing and sacrifice other ride qualities.

As for "aero" it can be important, even at lower speeds (a point which is often overlooked or denied). You will feel aerodynamic drag more a higher speeds, but drag coefficient is always will be a constant proportion of your power output even at lower speeds.  Therefore if you are doing long events at slower speeds it can still play an important roll and can still compound for large differences. For casual riding squeezing every bit of aerodynamics out will have a limited benefit as most won't notice a one or two minute change to their riding time.

That said, even if you are interested in aerodynamics there are lots of places to improve upon before you get to the bike.


Position - the single biggest source of drag.  Some clip-on aero bars will make a large improvement, so will lowering the handle bars at the cost of comfort.
Clothing - loose clothing adds drag.  Skin suits will have the lowest drag, but then it could be pretty awkward going into a coffee shop.
Helmet - more of a time trial consideration, and depends 
Aero wheels
Aero bike frame


Item (3) and (4) could be inverted, but it shows you how far down the list the aero bike is.  When you are racing and sometimes competing for seconds or even inches it can be an important difference.  For casual riding, getting the bike to fit well, using good tires and keeping the bike in good working condition will provide a much more noticeable improvement in the riding experience.