Judge the Backrest in Its Existing Position
Without back height adjustment, you cannot move the backrest vertically to change where its contours meet your back. Sit fully into the chair and assess that contact before making visual comparisons. With office chairs, a comfortable first impression is useful, but representative desk tasks reveal more about the relationship between seat, backrest and working reach. Notice if you keep contact naturally or repeatedly move away from the backrest. A black base does not indicate how the upper chair is shaped. Treat the fixed backrest position as a fit question that needs an individual answer.
Relate Black Bases to the Floor and Desk Frame
A black base can be visually distinct on a light floor or less prominent among dark desk supports. Neither effect follows from color alone; lighting, surrounding finishes and the visible shape of the base all contribute. Position office chairs where they will actually be used and inspect the view beneath the desk. A black base with fixed backrest height can provide the desired lower-level color while the seat and backrest remain visually separate. Check those surfaces individually. If several chairs face different directions, consider how much of each base is visible from the main circulation route.

