Bicycle Mechanics - Will at 700 x 25 tube fit a 26" x 2" tire???

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Scorer75
09-19-06, 07:32 AM
Last night I got about 4 miles from my office and got a flat. Par for the course riding in NY. IT's almost like my tires never touch the ground, but ride on roads of broken glass instead.

Anyways, I pull over, take out my flat kit and realize I packed my road bike tube instead of my mountain bike tube.

Being in a rush to make a dentist appointment, I called a co-worker who was nice enough to pick me up and give me a lift home.

The question is: Could I have used my 700 x 19-25 presta tube on my 26" x 2" tire and schrader valve rim to get home which would have been another 15 miles or so???


Before the lessons start, I now double check the tube before I leave, AND carry a ptach kit. I've never had ery good luck with patches but I've saved some tubes with holes and am working on it.

well biked
09-19-06, 07:49 AM
I've never tried that combination but I think it would have been likely to pinch flat with the too-large diameter tube, but I would have probably given it a try as a temporary fix, and ridden slowly. The presta valve would have been a non-issue. The fact that the road tube was not designed for as much volume as the mtb tire would have been much less than ideal also, but still might have worked to get you home..............In a sort of oppposite situation, I was mountain biking about a year ago with a guy who was riding a 29" (700c rim with fat knobbies) mtb; he had a flat, no tube, and he successfully stretched one of my 26" x 2" tubes over his rim and we rode on-
Rowan
09-19-06, 09:27 AM
Yes you could for a short-distance emergency. I have done so on the bike of another person who had not brought an MTB tube with her. I used a 700x25. The problem is that the tube will keep the tyre reasonably inflated, but move inside the casing as the bike moves along (at least, that was what was demonstrated in this example). The other factor would be valve-hole size -- if the MTB ran presta tubes and you tried replacement with schraeder valves (of any size), it wouldn't work because of the differences in valve thickness.