As I said before - adjustable geometry yes; adjustable at the head tube - no (with a couple of exceptions like Mongoose and VP Varial headset). Most adjustable geometry bikes (I've owned a few) change the geometry via the rear suspension linkage/shock mount. The end result is slackening the bike results in shorter reach. If you instead change angle of the head tube itself you lengthen reach (which is what I'd prefer). I go on road trips where I'll ride in very different places using one bike; so this would be useful to me - it may not matter to you.hat you are saying in 4. is already available. Parking lot adjustable geo was featured on some dh bikes and it is available on the new canyon among others.