I found that, under cygwin, chmod will not change groups permissions on a file that is stored on NTFS. The group owner needs to be change to User first.
$ chown :Users filename
Then chmod works as expected.
$ chmod 700 filename
Jay Everson has over 20 years experience supporting production infrastructure and software R&D Labs. He has 12+ years experience in management and has also spent time in Software Engineer, Infrastructure Architect and Team Lead roles.