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  1. #1
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    Tube confusion - 27" AND 700c?

    OK, so I wanted to replace a tube on my new-to-me old touring bike. The bike has 27 x 1 1/4 inch wheels. I went to the LBS, and bought tubes in a box clearly labeled as 27 x 1 1/4". I pulled the tube out of the box, and it was stamped 700c. Hmm. I looked at the other, different style box and that label read "27 inch and 700c". Are the tubes for these tires really interchangable?

    Both of the new tubes I tried to put on the rim were WAY too big. Which also confuses me, because I was under the impression that 700c were smaller diameter rims?

    What am I missing here? And where should I look for "true" 27" tubes?

  2. #2
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    Tubes are stretchy , and the size difference between 700c and 27" is only 8mm, a little more than 1/4" so they work for both. You want some that are for 700c x 25-32 and not the 23mm (for skinny tires). When inflated and not inside a tire they tend to expand larger than the tire. Put in just enough air to give them shape.


    Quote Originally Posted by HoustonGal
    OK, so I wanted to replace a tube on my new-to-me old touring bike. The bike has 27 x 1 1/4 inch wheels. I went to the LBS, and bought tubes in a box clearly labeled as 27 x 1 1/4". I pulled the tube out of the box, and it was stamped 700c. Hmm. I looked at the other, different style box and that label read "27 inch and 700c". Are the tubes for these tires really interchangable?

    Both of the new tubes I tried to put on the rim were WAY too big. Which also confuses me, because I was under the impression that 700c were smaller diameter rims?

    What am I missing here? And where should I look for "true" 27" tubes?

  3. #3
    Senior Member
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    I think that tube is suppose to be compatible with your 700 but I also think it's less than ideal.
    I ride 700 X 23 tires and prefer ultralite tubes that are marked 700 X 18 - 23, or 18 - 25.

    Al

  4. #4
    biked well well biked's Avatar
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    dcullen is correct, the tubes are interchangeable. The bead diameter of a 27" rim is 630mm, 700c is 622mm, not enough to matter. You say the wheels are 27 x 1 1/4, what is the size of the tire you're using? More than likely 27 x 1 1/4 I would think, and if so that would be roughly equivalent to a 700 x 32c tire. I don't know why the tubes would be too big, are you saying they seem too fat or too large for the rim diameter?

  5. #5
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    Too large for the rim diameter. I tried lightly inflating them and putting them in the tire, and there was no way all the tube could fit on the rim in the tire.

  6. #6
    biked well well biked's Avatar
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    Quote Originally Posted by HoustonGal
    Too large for the rim diameter. I tried lightly inflating them and putting them in the tire, and there was no way all the tube could fit on the rim in the tire.
    As long as you've got a good match to the width of tire you're using (1 1/4", 32mm, etc.), and your wheels are indeed 27" and the tubes are 27" (or 700c), it should work. Try deflating the tube all the way, put the valve stem through the rim hole, and then carefully work your way around the tire slipping the tube inside the tire's casing. Make sure there are no twists in the tube and that the tube is tucked completely inside, put the bead of the tire back on the rim and inflate enough to seat the bead, then check that there are no bulges, etc. If everything looks good, inflate some more and check again. If it's still good, bring it up to pressure and you should be good to go-
    Last edited by well biked; 03-29-07 at 02:52 PM.

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