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The article reports on the frequency shift of Raman spectra taken at different locations along the same single-walled nanotube (SWNT) showing different results when the SWNT is freely suspended or when interacting with the substrate. It reports that the substrates used in the study were silicon wafers with thermal oxide on the surface, which contain trenches (300 nm deep, 1-80 μm wide) fabricated by photolithography and dry etching. It argues that the dramatic Raman frequency variation for the same SWNT may be due to its radial deformation when lying on the substrate. It suggests that the effect is more obvious with larger diameter nanotubes and appears to be chirality dependent.