pinch flats

Someone please help me out in understanding the term. I have always
thought of pinch flats as what happens when a tube is improperly seated
in the tire ans gets "pinched" between the tire and rim wall.

In this group lots of folks seem to refer to pinch flats as what
happens with "too small" tires for the load being carried. Is the idea
that the load essentially flattens the tire and thus "pinches" the tube
between the tire and rim body?

If this is so I have never seen that happen. Is it really a matter of
load or insufficient inflation?

Thanks!

"gds" wrote in message
ups.com...
Someone please help me out in understanding the term. I have always
thought of pinch flats as what happens when a tube is improperly seated
in the tire ans gets "pinched" between the tire and rim wall.

This usually results in a blowout. I've never thought of this as a "pinch
flat."

In this group lots of folks seem to refer to pinch flats as what
happens with "too small" tires for the load being carried. Is the idea
that the load essentially flattens the tire and thus "pinches" the tube
between the tire and rim body?

Yes. aka a "snakebite" since it frequently causes two holes, one on each
side.

If this is so I have never seen that happen. Is it really a matter of
load or insufficient inflation?

Yes, either. The impact (such as bouncing up over a curb or hitting a big
enough rock) can also dent your rim if it's sufficiently violent.

RichC

thanks!

"Rich Clark" clip) I've never thought of this as a "pinch flat." (clip)
^^^^^^^^^^^^^^^^
There is a little bit of overlap of teminology. The type of flat caused by
trapping the tube in mounting is commonly called "pinching the tube." This
can be between the bead and the rim, or between the tire iron and the rim or
bead.

Leo Lichtman writes:

I've never thought of this as a "pinch flat."

There is a little bit of overlap of terminology. The type of flat
caused by trapping the tube in mounting is commonly called "pinching
the tube." This can be between the bead and the rim, or between the
tire iron and the rim or bead.

The difference is that this is not a flat but rather a tire patching
error that doesn't occur while riding. Flat tires are those events
that occur from riding the bicycle (or malicious activity). If you
damage the inner tube while remounting the tire then you discover it
immediately when you try to inflate the tire.

The pinch flat and the snake bite (double pinch) are caused by
compression failures the same as when bumping one's head on a flat
solid object, like a low concrete ceiling, to causes bleeding.

Jobst Brandt

gds wrote:
Someone please help me out in understanding the term. I have always
thought of pinch flats as what happens when a tube is improperly seated
in the tire ans gets "pinched" between the tire and rim wall.

In this group lots of folks seem to refer to pinch flats as what
happens with "too small" tires for the load being carried. Is the idea
that the load essentially flattens the tire and thus "pinches" the tube
between the tire and rim body?

If this is so I have never seen that happen. Is it really a matter of
load or insufficient inflation?

Thanks!

I think it is something like that when you hit a rock or a decent
pothole the tire can't hold its shape and the tube gets pinched between
the rim and the obstacle.
Bill

The couple of pinch flats I had were from a rookie mistake: not checking
my air pressure. Walking home 3 miles taught me the wisdom of topping
off the tires before I roll out the door. It is pinching the tire and
tube between the street surface and the rim.

I got a couple of really bad pinch flats in Holland, where the mortar
was missing between the pavers on the bike trail, and I rode into the
gap.

Bill Baka writes:

Someone please help me out in understanding the term. I have always
thought of pinch flats as what happens when a tube is improperly
seated in the tire and gets "pinched" between the tire and rim
wall.

In this group lots of folks seem to refer to pinch flats as what
happens with "too small" tires for the load being carried. Is the
idea that the load essentially flattens the tire and thus "pinches"
the tube between the tire and rim body?

If this is so I have never seen that happen. Is it really a matter
of load or insufficient inflation?

I think it is something like that when you hit a rock or a decent
pothole the tire can't hold its shape and the tube gets pinched
between the rim and the obstacle.

You may have the picture right but the description may be misleading.
The tube does not actually get pinched between rim and obstacle. It is
pinched between the side walls of the tire, the rim being outside of
the tire bead. Its shape is like pinching your cheek.

Jobst Brandt

wrote:
I got a couple of really bad pinch flats in Holland, where the mortar
was missing between the pavers on the bike trail, and I rode into the
gap.

This reminds me... i just remembered. I dreamed last night, or this
morning, that I was fixing a flat tire! I was about to take out my bike
when I noticed the tire was flat. I thought, oh S***....so I set about
fixing the flat. At first I wasn't sure I'd done a very good job, so i
asked a friend (another cyclist who is very tech savvy) if he could take
a look at it. He said I did it fine, but I just needed to inflate it a
bit more. I said fine, I'd do that, and I was surprised I'd done a good job!