a seat post and saddle change alters Setback . that being the distance behind

a Plumb line through the BB axis rearward & is a way to measure that .

different seatposts have different set back capabilities.. as do the rails of different saddles.

so the adjustment is not part of bike size selection,
but changing some of the component parts that were chosen to complete it as a bicycle,

for initial shipping.


parts can be changed