I think there may be some misunderstanding here. I could be wrong, but replacing a tubular's tube only involves opening up a small section of stitching, then inserting and re-glueing together the ends of a new cut-open tube. The original stitching and even the thread holes shuld be preserved as much as possible. Still more work than I've yet accomplished wrt repairing tubulars.
I have to add that I've had pretty terrible luck with cheap tubulars, whether Giros, Vittorias or Michelin cotton-variety tires. Too many tread bubble failures and too many flats. I run pressures of only about 95-100psi. The construction of the cheap tires folds 2-ply cotton over the "beads" (edges), leaving 4 plies here but only two under the tread! Contrast this to the better tubulars that achieve 4 or 5 thin, hi-tpi plies overlapped under the tread with a single ply folded over the edges, putting the extra thicknesses of hi-density casing where it's needed to prevent puncture at minimal weight.
Why are cheap tubular fabrics so prone to allowing the tube to escape and form the dreaded tread bubble? I've never had cheapo clinchers do this. Maybe the relatively (slightly) higher pressure? I have at least run the cheapest of 23mm gumwalls up around 90psi without problems, but have to admit I didn't suffer through too many a set of those.
David Snyder
Auburn, CA
i tried repairing tubulars a couple of times - that was enough for a
lifetime. this guy opens them up completely, replaces the inner tube, and
then re-stitches them with an industrial sewing machine. at $16 each for
two or more tires (including return shipping), it aint cheap but it is worth
it for nice/expensive tubulars with otherwise plenty of life in them.