American Friend wrote:
ah, I see now. So nothing to do with this frame.
As for your question about mixing tubes, it was not uncommon on custom frames, especially touring frames. Reynolds even had a special tubeset called Designer Select with mixed tubes at one point, but custom framebuilders in the UK had already been mixing tubes from different tubesets for years. Sometimes I suspect this may have been done partly out of expediency, using what was at hand, rather than for pure design reasons, but plenty of good framebuilders in the UK sometimes mixed tubes from different tubesets on custom frames because they felt a better frame could be built that way in certain cases. I should re-word that. Mixing tubes wasn't so uncommon. I think what happened is that after Reynolds started introducing new tubesets, framebuilders started experimenting with mixing them, whereas for decades all that had been available was 531, although even 531 had different varieties that could and were mixed sometimes. I suppose there was also a commercial argument for offering custom frames with mixed tubes as it was a way of making an already custom frame even more unique and special. Apologies to the OP for the digression.
Correct, mixing tubes has for many decades been common practice amongst the top British framebuilders, and there is much confusion among enthusiasts about tubesets - Reynolds in particular. For example; Designer Select is not strictly speaking a tubeset, neither is 653; 653 is a concept tubeset
and is a mix of 753 and 531 tubes - 653 replaced the 531 Professional
tubeset which in turn replaced the 531 Superlight
Reynolds would also produce one-off sets if the builder was sufficiently highly regarded. For example, I have a rare"Allin"that is built from a tubeset akin to 531 Superlight
many years before that set became commercially available.
Apropos the question of tube suitability: that is surely an issue for the builder and the true
use the rider will put the bicycle to? A top builder will want to consult the customer in some detail (notwithstanding the issue of correct sizing), as the SBDU did when I ordered my frame in the 1980s.
P.S Roadking, as in the American motorcycle of that name
Co-founder of a V-CC section, member South Eastern Road Club and owner of - 2005 Bianchi Reparto Corse (modern), 1985 Raleigh SBDU Pro Super, 1984 Raleigh LU Corsa, 1980 Allin Stan Butler Special, 1978 Ron Cooper, 2 x very ealry Roberts (late 60s/early 70s), 1975 Bill Philbrook tourer, 1966 Raleigh Superbe Roadster 1964 Allin Stan Butler Special Belgique, 1951 Hobbs of Barbican S/C, 1950 Hobbs of Barbican S/C, 1947 Hetchins Super Special, 1908 Centaur Featherweight.