Originally Posted by
prj71
Also a bad idea. Geometry of the bike keeps constantly changing with those things.
The bike's geometry doesn't change; the rider's position relative to the geometry changes. Moving your seatpost up or down or moving your saddle forward or back doesn't affect the bike's geometry at all -- imagine what geo charts would look like if they did.
But regardless, on-board changes to geometry are not necessarily a bad thing; any front- or full-suspension bike actually
does have a constantly-changing geometry, and people seem to ride those without trouble.
Besides, most suspension posts have a maximum of 40mm of travel; in most conditions, only a fraction of that is actually used, and the motion is barely perceptible beyond the reduction of jarring bumps.
Try one sometime. I recommend the PNW Coast, as it doubles as a dropper. (Dropper posts don't change a bike's geometry either, btw.)