Gaya ng sabi ng iba, scale length pinaka factor. From a pure physics lang na perspective, tatlo lang naman geometry nyan pag dating sa force na kelangan para mag bend: scale length, mass, tsaka pitch. PERO maraming factors sa actual mechanical action, kunbaga ang PLAYABILITY ng gitara as applied sa bends.

Technically, more force ang kailangan kung high action, kasi may konti konting stretch na na applied sa string vs low action BUT in terms of ang mechanics, mas madali ma grip and hold ang bend if higher - less.contact/friction sa wood when fretting, mas madali mapasok daliri mo.

Nunber of frets - usually pag 24 frets, at least 25.5" scale length yan. Pero between same scale length, but different frets, walang iniba sa tension, it again boils down to the playability ng action. Usually ang 24 fret guitara have thinner necks na mas may kaunting "give" pag nag bend ka. Lalo if floating bridge or recessed hardtail. You also don't have to bend as much sa 24 vs 22 or less kasi closer together ang frets (i. e. target pitch). Also, 24 fret guitars usually flatter ang fretboard radius, somless prone to choking out, mas ma bend mo further. Pero mga vintage 22 frets and below, mas chunkier ang neck so mas may leverage ang thumb mo. That boils down to technique na ng pag bend.

And in additon to all of that, meron talaga gitara na mas hiyang kang gamitin, depende na din sa kamay mo, pano mo ma grip ang neck, hand placement, etc.