My 1927/8 Flyer frame has a strengthening tube between the rear two upper tubes. Is this a standard feature on these frames? I don’t recall seeing any others but perhaps I haven’t been very observant.
Only the 1927 and 1928 long wheelbase Flyer frames have it. They also have two little vertical struts to take the saddle springs, to avoid having to have springs that are long and more prone to flexing sideways. A good detail that that they should have been kept on the later models.