Regarding the compatibility of Shimano electronic derailleur front mechs and the SM-AD67, or rather
whether the support bolt makes contact
I received a comment saying
「With the SM-AD67, the 9000, 9070, and 6870 all equally don't contact the support bolt, right?」
so I quoted it as-is, but then I received a different comment from someone else saying
「I don't have the 6800, 9000, and 9070 on hand,
but the support bolts on the 6870 and 6770 do contact the SM-AD67.」
The latter person provided this with definitive photo evidence from their own bike,
and when I looked at it,
the support bolt was indeed making contact (meaning it's doing its job).
I wanted to get a clear resolution on this,
so I got an SM-AD67 in stock.
Unlike the SM-AD79/90, the hole for the front mech fixing bolt
is positioned slightly lower, not at the height of the band and coaxial area.
This blog has a policy of「using self-taken photos as much as possible」
and「not casually linking to other people's blogs」
so I won't repost the photos I received as-is.
（But they were a huge help. Thank you so much!）
↑This is a locally-sourced photo
This is the FD-6770.
Looking at it again now, it's pretty big.
Here's the support bolt.
I've installed the SM-AD67.
The support bolt is faintly visible,
but it's making proper contact with the band.
Next I'll also install it on the FD-9070 and 6870.
Starting with the 6870.
Here's where the support bolt is positioned.
I've installed the AD-SM67.
The bolt is more visible than with the 6770,
but the support bolt is still making contact.
From the side, the bolt isn't visible.
Next is the 9070.
It's almost identical to the 6770 and 6870.
The support bolt is faintly visible,
but it's definitely doing its job.
To begin with, the band shape itself is
definitely designed with the support bolt in mind.
Also, the radius on the front mech band mounting area
is quite deep.
This is another point that recommends going with the dedicated part.
The FD-6870 manual says
「Please use bands SM-AD79/90/67」,
and I've now confirmed that whether it's 79/90 or 67, the support bolt makes contact.
Next I'll do a similar verification with the mechanical FD-6800 direct-mount type.
The support bolt is positioned slightly below the front mech fixing bolt axis —
which is about the same as the electronic type —
but the fore-aft position is further back on this one.
When I installed the SM-AD67, the support bolt didn't make contact.
The person who left the initial comment probably
tested it on an FD-9000.
Based on my verification results,
both mechanical and electronic types have support bolts at roughly the same height, but differ in fore-aft position.
Because of this difference in fore-aft position, with the SM-AD67 and mechanical direct-mount front mechs,
the support bolt doesn't make contact.
My reason for using the SM-AD90 with the FD-6770 the other day
was another reason entirely, and since it's confidential workshop info I can't write about it,
but I believe Shimano is doing this "knowingly"
because of a certain structural design detail that I'm into.
This is separate from the support bolt issue, so
of course there's nothing wrong with the FD-6770 and SM-AD67 combination.
To put it briefly, it has to do with the gear disengagement of the derailleur cage.
whether the support bolt makes contact
I received a comment saying
「With the SM-AD67, the 9000, 9070, and 6870 all equally don't contact the support bolt, right?」
so I quoted it as-is, but then I received a different comment from someone else saying
「I don't have the 6800, 9000, and 9070 on hand,
but the support bolts on the 6870 and 6770 do contact the SM-AD67.」
The latter person provided this with definitive photo evidence from their own bike,
and when I looked at it,
the support bolt was indeed making contact (meaning it's doing its job).
I wanted to get a clear resolution on this,
so I got an SM-AD67 in stock.
Unlike the SM-AD79/90, the hole for the front mech fixing bolt
is positioned slightly lower, not at the height of the band and coaxial area.
This blog has a policy of「using self-taken photos as much as possible」
and「not casually linking to other people's blogs」
so I won't repost the photos I received as-is.
（But they were a huge help. Thank you so much!）
↑This is a locally-sourced photo
This is the FD-6770.
Looking at it again now, it's pretty big.
Here's the support bolt.
I've installed the SM-AD67.
The support bolt is faintly visible,
but it's making proper contact with the band.
Next I'll also install it on the FD-9070 and 6870.
Starting with the 6870.
Here's where the support bolt is positioned.
I've installed the AD-SM67.
The bolt is more visible than with the 6770,
but the support bolt is still making contact.
From the side, the bolt isn't visible.
Next is the 9070.
It's almost identical to the 6770 and 6870.
The support bolt is faintly visible,
but it's definitely doing its job.
To begin with, the band shape itself is
definitely designed with the support bolt in mind.
Also, the radius on the front mech band mounting area
is quite deep.
This is another point that recommends going with the dedicated part.
The FD-6870 manual says
「Please use bands SM-AD79/90/67」,
and I've now confirmed that whether it's 79/90 or 67, the support bolt makes contact.
Next I'll do a similar verification with the mechanical FD-6800 direct-mount type.
The support bolt is positioned slightly below the front mech fixing bolt axis —
which is about the same as the electronic type —
but the fore-aft position is further back on this one.
When I installed the SM-AD67, the support bolt didn't make contact.
The person who left the initial comment probably
tested it on an FD-9000.
Based on my verification results,
both mechanical and electronic types have support bolts at roughly the same height, but differ in fore-aft position.
Because of this difference in fore-aft position, with the SM-AD67 and mechanical direct-mount front mechs,
the support bolt doesn't make contact.
My reason for using the SM-AD90 with the FD-6770 the other day
was another reason entirely, and since it's confidential workshop info I can't write about it,
but I believe Shimano is doing this "knowingly"
because of a certain structural design detail that I'm into.
This is separate from the support bolt issue, so
of course there's nothing wrong with the FD-6770 and SM-AD67 combination.
To put it briefly, it has to do with the gear disengagement of the derailleur cage.