Originally Posted by
Duragrouch
(above) Yeah I was equally confused about info online.
And I still cannot grok why the Enlighten-Mount seems to have elongated holes top and bottom; I could see if there was a sliding plate behind those holes, but that would only be to make the mount (also) accept Brompton mounts, and it doesn't, right?
My best guess is to allow for some ability to change fractionally the placement of the rack or bag adapter to account for variance in and around the head tube (e.g. variance in the location where the mount was installed; difference in types of headset cups). The metal insert that goes behind that bracket has some ability to move up or down.
My second best guess is to account for variance in the "angles" of the holes in racks or bag adapters themselves, along the lines of what Schwinnsta was talking about with 3rd party adapters he's encountered.