The SFI++ consists of \sim 5000 spiral galaxies which have measurements suitable for the application of the I-band Tully-Fisher ( TF ) relation .
This sample builds on the SCI and SFI samples published in the 1990s but includes significant amounts of new data as well as improved methods for parameter determination .
We derive a new I-band TF relation from a subset of this sample which consists of 807 galaxies in the fields of 31 nearby clusters and groups .
This sample constitutes the largest ever available for the calibration of the TF template and extends the range of line-widths over which the template is reliably measured .
Careful accounting is made of observational and sample biases such as incompleteness , finite cluster size , galaxy morphology and environment .
We find evidence for a type-dependent TF slope which is shallower for early type than for late type spirals .
The line-of-sight cluster peculiar velocity dispersion is measured for the sample of 31 clusters .
This value is directly related to the spectrum of initial density fluctuations and thus provides an independent verification of the best fit WMAP cosmology and an estimate of \Omega ^ { 0.6 } \sigma _ { 8 } = 0.52 \pm 0.06 .
We also provide an independent measure of the TF zeropoint using 17 galaxies in the SFI++ sample for which Cepheid distances are available .
In combination with the “ basket of clusters ” template relation these calibrator galaxies provide a measure of H _ { 0 } = 74 \pm 2 ( random ) \pm 6 ( systematic ) km s ^ { -1 } Mpc ^ { -1 } .