Not necessary, can be simply incorrect saddle position. First, and foremost - saddle should be set at correct height, horizontal offset and angle. E.g. the same saddle that absolutely doesn't work for me can change from "hurts as hell after a single lap in the parking lot" to "can tolerate up to 50 miles" - just by playing with the positioning. And the saddle that works for 20 miles may be actually a perfect saddle for you - just incorrectly positioned.
Last edited by Oso Polar; 12-05-19 at 10:41 AM.