If I had to take a guess it would be cutting open the down-tube to make a storage compartment, the stiffness around the BB area is directly impacted by it (I remember seeing -10 or -15% in stiffness in one of the threads here). I've only ridden a 2017 Giant TCR before and I can immediately feel the difference while climbing out of saddle.
You can't compare a TCR to the LCR018-D. Its not a like for like comparison.
Ive ridden my LCR018-D over 2000km now and it has been superb - smooth and faultless, the perfect everyday training bike, out in any weather.
I still think its great fun to ride, its light and fairly responsive - but its an endurance geo frame, so its never going to feel like a TCR or an SL6/7/8 (ive had a TCR and an SL6 in the past for comparison).
Just to note - as a bike thats out in all weather, I gave it a ceramic coating last week (CarPro SiC Quartz) and it has really opened my eyes to ceramic coatings.
First off, the bike looks bonkers good (glass like shine and smooth to touch), but the real benefit is the cleanliness. The application was as easy as a polish - simply rub one, wait and buff.
After being out on wet mucky roads yesterday, I came home and there was a layer of muck on the underside of the down tube.
Instead of the usual scrubbing match to get it off, I ran my finger along it and watched everything fall straight off - it was fantastically satisfying!
The SiC is available in very small bottles (10ml for £14.95), and I was able to coat the bike frame 3 times and still have some left over - can't be bad to that value.
I want a super light aero bike that can climb, and im pinning hopes on Peters new aero frame coming out soon, but the LCR018-D will be my everyday workhorse - a job it is performing beyond my expectations.