Joined: Jan 2010
Posts: 9,835
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From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
I've seen cheap tubulars do that many times, but on a smaller scale, as also cited by verktyg.
What has happened is that the tube has slipped past the pressure-containing casing of the tire, do to some discontinuity/irregularity in the tire casing. Very fast production rates using coarser grades of casing fabric tend to cause this, though I myself have had only good luck with these seemingly-exact (C-740?) model of Cheng Shin tires. It is almost unbelieveable that the tread rubber is containing the pressure by itself, so I am assuming a low pressure was used(?).