Hi,

I have a mountain bike with stock tire and tube 26X1.95. I recently changed the tire to slick
26X1.95 (90PSI) but still using the old tube.

Is that OK? or I must change the tube also?

Thanks!

On Sun, 18 Jan 2004 01:50:47 -0500, Chen Chen
<cc2fc@node10.unix.Virginia.EDU> wrote:

>Hi,
>
>I have a mountain bike with stock tire and tube 26X1.95. I recently changed the tire to slick
>26X1.95 (90PSI) but still using the old tube.
>
>Is that OK? or I must change the tube also?

If you got it in without twisting or pinching it and it's holding air then all is well. jb

Chen Chen wrote:

> Hi,
>
> I have a mountain bike with stock tire and tube 26X1.95. I recently changed the tire to slick
> 26X1.95 (90PSI) but still using the old tube.
>
> Is that OK? or I must change the tube also?
>
> Thanks!
>

I assume the header of your e-mail is correct (26" x 1.25"). If the tube fitted it is OK.

Useful tip: 24" x 1 3/8" tubes fit narrow MTB tyres perfectly well and are often easier to find than
narrow 26" tubes. There is a small difference in diameter, but all tubes increase a lot in diameter
when inflated.

On Sun, 18 Jan 2004 01:50:47 -0500, Chen Chen
<cc2fc@node10.unix.Virginia.EDU> may have said:

>
>Hi,
>
>I have a mountain bike with stock tire and tube 26X1.95. I recently changed the tire to slick
>26X1.95 (90PSI) but still using the old tube.
>
>Is that OK? or I must change the tube also?

Same size tire? The old tube should have no problem at all. The tube doesn't know whether there are
knobs on the outside of the carcass.

(Now, if you had swapped down to a 26x1.25, as I'll be doing on one of the bikes next weekend, you
would probably have needed different tubes.)

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.

On Sun, 18 Jan 2004 01:50:47 -0500, Chen Chen
<cc2fc@node10.unix.Virginia.EDU> may have said:

>
>Hi,
>
>I have a mountain bike with stock tire and tube 26X1.95. I recently changed the tire to slick
>26X1.95 (90PSI) but still using the old tube.
>
>Is that OK? or I must change the tube also?

Oh, wait; the *header* shows a significant size decrease.

Okay, here's the deal:

If the tube was one of the very stretchy varieties which shrinks back down to a very small diameter
when deflated, and if that diameter is below the equivalent enclosed volume of the installed tire on
the rim, then it should work without any trouble. If the tube's size when just barely inflated is
larger than the enclosed volume, it will almost certainly end up with wrinkles. Wrinkles may not
cause a problem for hours, days, or weeks, but most likely will result in a failure at some
point...and it's likely to be a failure that will resist patching.

Most tubes that I've used have had a size range marked on them to tell the user what sizes of tire
they are appropriate for. It's wise to pay attention to those markings, although for my own bikes
I'll admit to having successfully gone beyond them in both directions when the only tube on the
shelf was not the right size for what I needed at that moment.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.

I too have used a 1.95 tube in a 1.25 tire without problems. The only worry I had was the tube
expanding too much and pushing the tire out of shape of off but it never happened.

"jeffbonny" <jeffbonny@REMCAPSshaw.ca> wrote in message
news:t8ck00dp0mbqj45ho6hf7jmmbetedjncr0@4ax.com...
> On Sun, 18 Jan 2004 01:50:47 -0500, Chen Chen <cc2fc@node10.unix.Virginia.EDU> wrote:
>
> >Hi,
> >
> >I have a mountain bike with stock tire and tube 26X1.95. I recently changed the tire to slick
> >26X1.95 (90PSI) but still using the old tube.
> >
> >Is that OK? or I must change the tube also?
>
> If you got it in without twisting or pinching it and it's holding air then all is well. jb

On Sun, 18 Jan 2004 06:23:43 -0500, "Raymo853" <raymo853@hotmail.com>
wrote:

Haven't tried this with my 27 X 1.25 road bike yet, but I will next tire. The existing tube has worn
out 4 nylon tires in about 6000 miles.

I sometimes partially inflate the tube to get the kinks out before deflating and rolling the final
bead over the rim anyways. I bet a 24 inch tube would be perfect for a road bike as well.

>I too have used a 1.95 tube in a 1.25 tire without problems. The only worry I had was the tube
>expanding too much and pushing the tire out of shape of off but it never happened.
>
>
>"jeffbonny" <jeffbonny@REMCAPSshaw.ca> wrote in message
>news:t8ck00dp0mbqj45ho6hf7jmmbetedjncr0@4ax.com...
>> On Sun, 18 Jan 2004 01:50:47 -0500, Chen Chen <cc2fc@node10.unix.Virginia.EDU> wrote:
>>
>> >Hi,
>> >
>> >I have a mountain bike with stock tire and tube 26X1.95. I recently changed the tire to slick
>> >26X1.95 (90PSI) but still using the old tube.
>> >
>> >Is that OK? or I must change the tube also?
>>
>> If you got it in without twisting or pinching it and it's holding air then all is well. jb

On Sun, 18 Jan 2004 06:23:43 -0500, "Raymo853" <raymo853@hotmail.com>
may have said:

>I too have used a 1.95 tube in a 1.25 tire without problems. The only worry I had was the tube
>expanding too much and pushing the tire out of shape of off but it never happened.

The tube is just a conformant bladder; the air pressure exerts the force, not the tube. If the
bladder's at-rest size is too large, it will wrinkle when inflated. This can cause a failure in the
tube. A tube that's "too big" can't blow the tire off the rim at the rated inflation pressure as
long as the *tire* is properly installed.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Words processed in a facility that contains nuts.

Thanks for all the replies. I have mount the tire on the tube with little
hassale. And inflated them to 90PSI. After 24 hrs they are still 90PSI.
I did not find a tube for 26X1.25 when I install the tire. Now I found
one, but I am planning to see how long those 26X1.95 tubes can last.
Chen
On Sun, 18 Jan 2004, Werehatrack wrote:

> On Sun, 18 Jan 2004 06:23:43 -0500, "Raymo853" <raymo853@hotmail.com> may have said:
>
> >I too have used a 1.95 tube in a 1.25 tire without problems. The only worry I had was the tube
> >expanding too much and pushing the tire out of shape of off but it never happened.
>
> The tube is just a conformant bladder; the air pressure exerts the force, not the tube. If the
> bladder's at-rest size is too large, it will wrinkle when inflated. This can cause a failure in
> the tube. A tube that's "too big" can't blow the tire off the rim at the rated inflation pressure
> as long as the *tire* is properly installed.
>
> --
> My email address is antispammed; pull WEEDS if replying via e-mail. Yes, I have a killfile. If I
> don't respond to something, it's also possible that I'm busy. Words processed in a facility that
> contains nuts.

On Sun, 18 Jan 2004 12:51:21 -0500, Chen Chen
<cc2fc@node13.unix.Virginia.EDU> wrote:

>
>Thanks for all the replies. I have mount the tire on the tube with little hassale. And inflated
>them to 90PSI. After 24 hrs they are still 90PSI. I did not find a tube for 26X1.25 when I install
>the tire. Now I found one, but I am planning to see how long those 26X1.95 tubes can last. Chen

After getting a tube that will actually fit on installation, the basic issues on tube sizing are-

A 'larger' tube will have more rubber, hence weight more.

A larger tube will not be stretched as much under inflation. This could potentially make the tube
more resistant to punctures- thicker material for any object to have to penetrate. I have known bike
messengers who swear by this, but I do not know if there is any validity to it.

You may have to reinflate less often- the 'pores' of the tube are not as stretched and open, leading
to less air pressure loss over time.

Conversely, a small tube will-

weight less be stretched thinner, potentially puncturing easier loss air pressure faster

Hi, another report: I bought a pair of 26X1.1-1.4 tubes and installed them on the 26X1.25 slick
tires. After inflating them to 90PSI, one tube blew immediately and the other blew hours later.
Tire--Performance fast city 90PSI max kevlar belt. Tube--Performance ATB 26X1.1-1.4 Now I changed
the tubes back to 26X1.95--2.125. They are bigger and after 10miles they ride and hold
pressure(90PSI) OK.

Chen "Dan Daniel" <ddandan.remove@pacbell.net> wrote in message
news:qall0019ln0h2dhk2lo5qim0du1tf1o7tm@4ax.com...
> On Sun, 18 Jan 2004 12:51:21 -0500, Chen Chen <cc2fc@node13.unix.Virginia.EDU> wrote:
>
> >
> >Thanks for all the replies. I have mount the tire on the tube with little hassale. And inflated
> >them to 90PSI. After 24 hrs they are still 90PSI. I did not find a tube for 26X1.25 when I
> >install the tire. Now I found one, but I am planning to see how long those 26X1.95 tubes can
> >last. Chen
>
> After getting a tube that will actually fit on installation, the basic issues on tube sizing are-
>
> A 'larger' tube will have more rubber, hence weight more.
>
> A larger tube will not be stretched as much under inflation. This could potentially make the tube
> more resistant to punctures- thicker material for any object to have to penetrate. I have known
> bike messengers who swear by this, but I do not know if there is any validity to it.
>
> You may have to reinflate less often- the 'pores' of the tube are not as stretched and open,
> leading to less air pressure loss over time.
>
> Conversely, a small tube will-
>
> weight less be stretched thinner, potentially puncturing easier loss air pressure faster

"Chen Chen" <cc2fc@virginia.edu> wrote in message
news:buk4u4$t3b$1@murdoch.acc.Virginia.EDU...
> Hi, another report: I bought a pair of 26X1.1-1.4 tubes and installed them on the 26X1.25
slick
> tires. After inflating them to 90PSI, one tube blew immediately and the other blew hours later.

Sounds like you got the tube between the tire and rim. For more on how to mount a tire, read the
Bicycle FAQ:

Blown tube: http://www.faqs.org/faqs/bicycles-fa...section-3.html

Blowout and Sudden Flats: http://www.faqs.org/faqs/bicycles-fa...section-2.html

Mounting tires: http://www.faqs.org/faqs/bicycles-fa...faqs/bicycles-
faq/part3/section-2.html

Chen Chen wrote:
> Hi, another report: I bought a pair of 26X1.1-1.4 tubes and installed them on
the 26X1.25 slick
> tires. After inflating them to 90PSI, one tube blew
immediately and the
> other blew hours later. Tire--Performance fast city 90PSI max kevlar belt.
Tube--Performance ATB
> 26X1.1-1.4 Now I changed the tubes back to 26X1.95--2.125. They are
bigger and after
> 10miles they ride and hold pressure(90PSI) OK.

I agree that what you say happened happened but it wasn't _because_ of the size of the tube.

It's more likely you either caught a bit of tube under a tire bead or pulled the valve base below
the edge of the tire. At any rate it failed _because_ the tire was not seated evenly. If it were,
pneumatic pressure acting evenly on the whole tire, it would not have come off the rim within the
normal pressure range.

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971

Zog The Undeniable <ggg@hhh.net> wrote in message news:<budht2$pf0$1@newsg3.svr.pol.co.uk>...
>
> Useful tip: 24" x 1 3/8" tubes fit narrow MTB tyres perfectly well and are often easier to find
> than narrow 26" tubes. There is a small difference in diameter, but all tubes increase a lot in
> diameter when inflated.

FWIW, I did this recently, putting 1.25" tires on some wheels that previously had 1.95"s. I bought
some 1.25" tubes to go with the new skinnier tires.

Interesingly, the 1.25" tubes had "26x1.25" stamped on the tube. But *molded* into the tube was
"24" x 1 3/8"!

So I guess this is indeed a useful tip!

papercut wrote:

> FWIW, I did this recently, putting 1.25" tires on some wheels that previously had 1.95"s. I bought
> some 1.25" tubes to go with the new skinnier tires.
>
> Interesingly, the 1.25" tubes had "26x1.25" stamped on the tube. But *molded* into the tube was
> "24" x 1 3/8"!
>
> So I guess this is indeed a useful tip!

And you thought bicycle engineering was a precise discipline ;-)