What is the new teminology for 27" x 1 1/4" sew ups? There are so many new sizes. It seem like 32-630 would be right, but I can't find any that arn't clinchers. I need new sew ups for my 1960 Paramount. And where can I get them?
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1I think you've found the term "tubular" already; this question suggests you're probably looking for a 622 or 630 size.– DavidWDec 1, 2022 at 4:51
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2 Answers
Disclaimer that I haven't dealt with this exact issue firsthand, but this is what Sheldon Brown, who is usually reliable and was a working mechanic in the time period when it came up more often, has to say about it:
Standard size tubular tires use a rim that corresponds in diameter to a 622 mm (700C) clincher rim.
Back in the 1970s, 622 mm clinchers were very rare in the U.S., and most sporty bikes used either 630 mm (27 inch) clinchers, or standard (622 mm) tubulars.
The fact that these sizes are so close led to an in-accurate habit of referring to "27 inch" tubulars. This careless nomenclature still causes confusion, and people often imagine that there is a different "27 inch" size in tubulars as there is in clinchers.
This is not true. THERE IS ACTUALLY NO SUCH THING AS A "27 INCH" TUBULAR.
All full-size tubulars fit all full-size tubular rims.
The answer is thus to get whatever normal 700C tubulars you want. If the ones you have now are wide like a 27x1-1/4" is and if the rims are also wide like that (say 22mm or wider), you should probably be looking at the wider size tubulars.
Alternatively, since clinchers are vastly improved compared to the ones of your bike's era, you could look at doing new rims and tires. Options do exist that would look the part, i.e. high polish box-section eyeletted with tan sidewalls.
answered Dec 1, 2022 at 20:57
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+1 to this. Unless this is a show bike that needs to be period-correct, converting to clinchers is the smart move. Dec 2, 2022 at 15:24
The word you need is "tubular" tyre, which is a combination of tyre and inner tube.
A tubular tyre ONLY suits a tubular rim, and vise versa. You'll need tubular glue or tape as well. Depending how the old one was attached, you may need a hot air heat gun to soften the glue and some kind of soft scraper, I found wooden iceblock sticks to be okay.
As for sizing, well its a mess generally with bike tyres. Yours is old enough to predate ETRTO standards, but 27" is a diameter and 1 1/4" is a width. I'd suggest sticking with a 30 or 32mm width because your tube has to fit your rim's curve.
However tubular tyres have a bizarre amount of "stretch" so I suspect a 622mm tubular will also fit a 630mm rim, and probably a 635mm rim with sufficient cussing/patience. Note I've not done this personally.
Also check the valve type before starting - 95% likely its a Presta aka F/V.
Allow 3 days on-and-off for the whole clean,glue,fit,cure process. Tubulars are not quick.
