Pinch flat...is this normal?

[Brett Jaffee]

I havent been riding too long, and got what I assume was my first pinch flat today. Odd thing (I
think) is that the tear/slit was on the inner part of the tube...ie, the part that is contacting the
rim, not the tire. Is that unusual?

I have been trying lower tire pressures, but I thought pinch flats usually occured on the side
of the rim.

 

[Bomba]

On Wed, 11 Feb 2004 07:17:15 +0000, Brett Jaffee wrote:

> I havent been riding too long, and got what I assume was my first pinch flat today. Odd thing (I
> think) is that the tear/slit was on the inner part of the tube...ie, the part that is contacting
> the rim, not the tire. Is that unusual?

No, perfectly normal.

> I have been trying lower tire pressures, but I thought pinch flats usually occured on the side of
> the rim.

Pinch flats occur when the tube is crushed between the object and rim - it is usually the rim
that causes the holes / slits. If you pinch flat, it is a sure sign that you're running your
pressures too low.

--
a.m-b FAQ: http://www.j-harris.net/bike/ambfaq.htm

b.bmx FAQ: http://www.t-online.de/~jharris/bmx_faq.htm

 

[Brett Jaffee]

D'oh, and after a closer look, the rim (Mavic 223) has a small dent...just my luck (or lack of
skill), as it was a new rim.

Oh, after re-reading my post...what I should have said was that I thought pinch flats usally occured
on the sides of the tube. My impression was that the slits usually came in "snake bite" pairs. This
one was a single, right on the centerline of the inside of the tube.

Not that it matters...obviously I hit something.

bomba <[email protected]> wrote in news[email protected]:

> On Wed, 11 Feb 2004 07:17:15 +0000, Brett Jaffee wrote:
>
>> I havent been riding too long, and got what I assume was my first pinch flat today. Odd thing (I
>> think) is that the tear/slit was on the inner part of the tube...ie, the part that is contacting
>> the rim, not the tire. Is that unusual?
>
> No, perfectly normal.
>
>> I have been trying lower tire pressures, but I thought pinch flats usually occured on the side of
>> the rim.
>
> Pinch flats occur when the tube is crushed between the object and rim
> - it is usually the rim that causes the holes / slits. If you pinch flat, it is a sure sign that
> you're running your pressures too low.

 

[Westie]

bomba wrote: <snip>
> If you pinch flat, it is a sure sign that you're running your pressures too low.

...or that your pressures are in a reasonable range, but you ride in such a way that you smash those
tyres hard against objects that wouldn't normally pinch flat for the majority of people. Learn to
ride more 'smoothly' and avoid smashing wheels against things. In the meantime, as bomba more or
less said, increase the pressures to counter-act the problem.
--
Westie (been there, done that, bent and broken those...) (Replace 'invalid' with 'yahoo' when
replying.)

 

[Bomba]

On Wed, 11 Feb 2004 11:16:59 +0000, Brett Jaffee wrote:

> D'oh, and after a closer look, the rim (Mavic 223) has a small dent...just my luck (or lack of
> skill), as it was a new rim.

Oh dear, someone's learning the hard way...

> Oh, after re-reading my post...what I should have said was that I thought pinch flats usally
> occured on the sides of the tube. My impression was that the slits usually came in "snake bite"
> pairs. This one was a single, right on the centerline of the inside of the tube.

You must have squished it on just one side of the rim. That's less common for sure.

PS - http://www.j-harris.net/bike/ambfaq.htm#1.2.1

--
a.m-b FAQ: http://www.j-harris.net/bike/ambfaq.htm

b.bmx FAQ: http://www.t-online.de/~jharris/bmx_faq.htm