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27" X 1-1/4" VS 70 CM (27-1/2")

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borgward

Finally riding a big boys bike
The tire on my Late 80's World Sport shows that it is 27" X 1-1/4". Looking for innertube, I see 700C which is 27-1/2". Is 27" the nominal size which is actually 27-1/2", or are 27" and 700C (27-1/2") tires and tubes different animals? If different, will 700C innertube work on my bike?
 
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27" and 700c take the same tube
Your tires will take a 700c 23-28 width for road bikes
27.5 is actually a crazy mix of a 650b diameter rim (584?) and a large tire so the tube is much bigger round for a much taller tire.
in real world application, a 700cx28 and a 27x1-1/4 are exactly the same in overall height. They take the same tube and most tube boxes will have both tire sizes on them.

I have found that the cheapest "bike world" tubes at Walmart are CST (Chinese) tubes and are of a good quality. I seem to always have issues with Kenda tubes.
 
Walmart has a lot of tubes and tires now. Last year I had to order tires and tubes for my Raleigh 3 Speed. Are the peel and stick patches any good? Decades ago all I ever did was glue on or vulcanize patches.
 
27" and 700c take the same tube
Your tires will take a 700c 23-28 width for road bikes
27.5 is actually a crazy mix of a 650b diameter rim (584?) and a large tire so the tube is much bigger round for a much taller tire.
in real world application, a 700cx28 and a 27x1-1/4 are exactly the same in overall height. They take the same tube and most tube boxes will have both tire sizes on them.

I have found that the cheapest "bike world" tubes at Walmart are CST (Chinese) tubes and are of a good quality. I seem to always have issues with Kenda tubes.
Now I need tires what is the equivalent for 27 X 1-1/4 tire. When I search for 27 X 1-1/4 tire all I get is 700C X ...
 
27 x 1 1/4 is (32-630)
1 1/4 inches is equal to 31.75 millimeters.
Now, different manufacturers' offerings of (32-630) 27 x 1 1/4 tires DO IN FACT VARY, and significantly sometimes as to the actual tread width, even though the sidewall marking says (32-630). Back in the day, the various manufacturers' tire offerings were nearly all close to the actual 32mm as marked (true to size), but not so today. It depends on the tire model and from what particular manufacturer. Some are true to size and there are a few that are as much as 3.5mm undersized in width, though marked as 32-630.

27" has bead seat diameter of 630mm (thus the 27" wheel is LARGER than the 700C which has a BSD of 622mm)

700C has bead seat diameter of 622mm

You generally can swap and interchange the 700C innertubes IF the tube's width size is compareable and wide enough because the rubber stretch properties have no trouble with the 8mm difference in bead seat diameter.
Obviously the tires cannot interchange!


 
So the 700 is not centimeters or millimeters, although 700mm would equate to about ~27.5 something inches.
The 622mm dimension might be used for 700c wheels, which might fit either 28” or 29” tires.
Older 27” rims like on 10-speeds are 630mm.

Some tubes are sold by the range of tires that they might fit (like as marked on the box), but some sellers only state one of those sizes.

Recently, the last 27” x 1+1/4” tubes that I purchased were marked on the box to also fit other sizes (e.g., 700-something). I believe that the markings, molded into the tubes, indicated a metric size.
 
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