Headset cup and steerer tube wear on rear side
I have a Cervelo Prodigy with an Aheadset threadless headset (unsure of model--it's the one that came stock on the white and silver Prodigy).
When I went to overhaul the headset, I noticed that there were worn spots/rub marks on the "back" of the steerer tube and top and bottom headset cups (if 12" oclock is pointing forward, then the marks are from about 5-7 o clock).
They're deep enough to be perceptible by running my fingers down them with my eyes closed, but probably not deeper than a piece of paper.
What would have caused this? Worn bearings/races? Misadjusted headset?
Marks on the steerer tube might have been from the install of the fork race or loose headset. The loose headset if ridden long enough would show uneven wear of the bearings to the headset cups and the front end would rattle, brakes would grab. If the headset were to tight then the steering would have felt tight but the headset cups usually look dimpled from the bearings imprinting into the cups(long term). Make sure cups are in the frame flush to the steerer tube.