first time i see a disc brake setup inside the frame triangle.

what is the pros and cons of inside vs outside? thanks!

inside...



outside...

my thoughts are that looks like maybe INSIDE might not interfere with a normal rear rack strut.
but looks like OUTSIDE is easier to adjust and service the brakes.

Every disc brake road or gravel bike I've ever seen has the rear brake mounted inside the rear triangle, on the chain stay.

Inside the stays is hardly a new development. If you havent seen that, its becauee you have been actively looking away.

Mounted on the chainstay is tucked out of the way from damage, makes racks easier to mount, and keeps the bike looking cleaner. There are probably other benefits too.

I would say i am shocked you havent seen this, but its right in line with your posts.

Inside, together with mechanical caliper isn’t a great combination. The end of the cable casing will point up, making it prone to collect water and humidity. Can be a considerable nuisance if you ride in freezing conditions.
Otherwise, as already mentioned, it allows for easier fender and rack install. A neater, cleaner look IMO. MIGHT offer more protection, although I can’t say I’ve ever actually benefited from that.

not significantly more than hitting the chainstay itself.

No joke. it's just that english is not his first language.
It took me a moment to figure it out yet what he is referring to is whether the disc CALLIPER is mounted above the chain stay and within the rear triangle or on top of the seat stay and outside the rear triangle.

i updated the first photo above to show the problem of water collection.

it seems like a significant design flaw.

i had once attached a chainstay kickstand, and my heel would scrap the kickstand.

so adding anything attached to the chainstay worries me.

Yep. Well known, been at it for awhile. Not even imaginative.