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Old 04-23-13, 02:01 PM   #1
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700c tube in a 650b tire?


I am repairing an old bike for a friend, and would prefer repairing it with what I have in stock - partly cause I'd like to repair it tonight so she'll have it to ride tomorrow morning. And that I like repairing bikes while sipping a beer and chatting with friends.

This is a 650b tire, should be half ballon, but is slightly narrower, probably 32mm or 35mm.
I have 650b tubes, should be "half balloon", but they are 44-585, which is IMHO too wide.
The original tube was maybe half as wide (strange, but hey, better a small tube in a large tire).

I put that wide 650b tube in the tire, but the tire did not seat very happily. Pumped it, seemed ok, started to repair another bike... And heard a big "Boom" one hour later from the tire unseating and the tube exploding.

I was thinking that I also have 700c tubes in way narrower width. Would they be an ok match? I know 26" tubes can go in 650b, but I don't have anything slimmer than 36*1,75. Yet 26" is 559 mm so it actually is a tad smaller, might do the trick better, but it's schrader, not presta. And while I would drill a modern aluminum rim, I wouldn't do the same on an old steel one...

Any suggestion?

Also: the explosion damaged the tire bead. Some gum was scraped, but that is the gum that goes after the wire bead, of which the metal is not exposed. Do you think I have any chance putting that tire back in?

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Old 04-23-13, 02:24 PM   #2
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There are widths in the 622/630 tubes , thin 23, med 32. wide 50, Aka 29er.

no visual inspections are possible in text only questions.

Last edited by fietsbob; 04-23-13 at 02:28 PM.
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Old 04-23-13, 05:23 PM   #3
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Unless you pinched the tube between the tire bead and rim, it sounds like you used too much pressure for a steel rim. I would use the 584-44 tube and put some air in it before mounting the second bead of the tire.
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
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