  We present bulge and disk (B/D) decompositions of existing K'-band surface
brightness profiles for 65 Ursa Major cluster spiral galaxies. This improves
upon the disk-only fits of Tully et al. (1996). The 1996 disk fits were used by
Tully & Verheijen (1997) for their discovery of the bimodality of structural
parameters in the UMa cluster galaxies. It is shown that our new 1D B/D
decompositions yield disk structural parameters that differ only slightly from
the basic fits of Tully et al. and evidence for structural bimodality of UMa
galaxies is maintained. Our B/D software for the decomposition of 1D surface
brightness profiles of galaxies uses a non-linear minimization scheme to
recover the best fitting Sersic bulge and exponential disk while accounting for
the possible presence of a compact nucleus and spiral arms and for the effects
of seeing and disk truncations. In agreement with Tully & Verheijen, we find
that the distribution of near-infrared disk central surface brightnesses is
bimodal with an F-test confidence of 80%. There is also strong evidence for a
local minimum in the luminosity function at M_K' ~ -22. A connection between
the brightness bimodality and a dynamical bimodality, based on new HI line
widths, is identified. The B/D parameters are presented in an Appendix.
