just at a curiosity, why is everyone picking the 168 over the 177? the 177 is lighter and they almost look identical. is the 168 marketed as aero while the 177 is lightweight? i mean putting the two together they look ALMOST IDENTICAL so im curious what everyones thought is. the geometry numbers are all within .5 degrees and under 10 degrees. stacks 5mm shorter. both come with an integrated bar and the only noticeable difference is the cutout for the rear wheel.
It is aero vs climb (according to Chris) but just marginally so.
Presumably part of the weight gain comes from aero shaped tubes. The seat tube appears narrower from front, with a elongated profile resulting in the cut-out.
The stack is slightly lower, and reach slightly longer for a more aggressive riding position.
The smaller rear triangle contributes to better aerodynamics from airflow passing over the rear wheel.
In the end, marginal aerodynamics are harder to achieve than than marginal weight losses (unless you are already optimal weight for the sport). And let's face it, most of us (not all) who can afford this hobby could always lose a pound or two. Instant watts!
Reality: I kinda liked the look of the 168 a bit more. I was sold when I found out the geometry is exactly the same as the Tarmac SL7. Also, I could put the $50 saved towards a fancy schmancy chameleon Paint job.