Bicycle Mechanics - ok to use the same tubes in 25c and 35c tires?

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Aussomeman
12-07-03, 08:22 PM
hi there-

i just purchased a set of 35c cyclocross tires to use on my fixie/beater bike in the lovely winter weather we've just begun to have here in new england, and i had a question about the tube size. i'm running normal 700x25c tires on the bike now, and the tubes are sized at 700x19-26c, i believe. now, i'm assuming that i could install the 35c tires with the same tubes and they'd just expand, but i'm just wondering, is that going to present a problem when i switch back to the 25c tires? are the tubes going to stretch out to the point where they'll be too big for the 25c's? i know i could just go out and get different tubes, too, but i'm just wondering if i could avoid doing that if i need to.

thanks!

-steve

Rev.Chuck
12-07-03, 09:14 PM
Putting them in the larger tires will stretch them some(more prone to puncture) and you might have a little trouble getting them back in the skinny tires as they will hold memory once stretched for a while. On the other hand this is the best way to get a "cheap" lite weight tube.
tommasini
12-08-03, 09:37 AM
undersized tubes also sometimes deflate much quicker when punctured because of the stretching, so it would be best to get the correct tubes

slider
12-08-03, 03:15 PM
I run 700 x 20-28C tubes in all my tires up to 35C just because I only like to keep one size lying around. Haven't noticed any increase in punctures or deflation rate. YMMV

-s
Dave Stohler
12-08-03, 03:28 PM
Undersized tubes tend to 'blow-off' patches while being inflated. If you're going to do this, bring a spare (new) tube along.
DieselDan
12-08-03, 08:04 PM
One point, don't try that with latax tubes.
sch
12-08-03, 09:37 PM
Rubber fails catastrophically, without any warning, like a balloon pops. If
the tube has any small defect, overinflation will tend to exacerbate that
defect, cause it to propagate and thus fail when the defect opens into a
hole. If you are lucky there will be no defects and you will get away with
overinflation. If not you will find out rapidly. Worst case will be a series of
pinholes that leak down over 1-2hrs. Save money and time by getting the
right size tube for the tire. The valve area will be a definite stress site.
Steve