We discuss some aspects of a paper which appeared recently in this jou
rnal [F. F. Lima, V. M. Oliveira, and M.A.F. Gomes, Am. J. Phys. 61, 4
21-422, 1993] in which the fractional dimension of rolling crumpled su
rfaces is measured experimentally. We show that this experiment may no
t actually be measuring fractal dimension kinematically at all. In add
ition, we report a variation of their experiment using. nonfractal gro
oved cylinders. The results indicate that large irregularities on the
surface of ''rolling'' objects may lead to errors in the dynamic measu
rement of the dimension of crumpled surfaces. (C) 1995 American Associ
ation of Physics Teachers.