I get your point, but it's not about the physical size of the cogs. And btw, the reverse of your "logical explanation" is true for the rings.

It's about gear ratios. Think up-shifting or down-shifting in a stick shift car. In a car, you can't actually see the gears, but down-shifting should be apparent to the driver that one is shifting to a lower gear ratio.

Even if twodownzero had gotten the up/down shifting thing right he's still wrong. Shimano can't shift up more than one gear at a time either.

Yeah my 105 5700 can only shift up once per click of the paddle. With the brake lever I can shift down multiple gears depending on how far I push. Same as Sram as far as function. Just does it a different way with the brake level and paddle vs all in a single paddle.

The 10 4, I love the SRAM Rival components on mine. Shifts flawlessly.

I've used both and prefer the SRAM Rival over 105. Personal preference. Hoods feel better and it's easier to shift in the drops with one finger.

I have larger hands so with the compact bars on the CAAD10-5 I can shift with one finger (up or down) with 105 too while in the drops. Honestly though I was new so either system I had no preference for. I picked my CAAD10 based on the frame color and went with the team version. Knowing I would be upgrading the wheels and groupset eventually.

I have ordered the caad 10 4 silver I wanted the gulf color first but I cant see myself riding the bike for more then a season hahah

in a couple of weeks I well get the bike Cant' wait dammit! picture of the bike upon arrival