Question - what causes blowouts and how do I prevent them?

"Arthur Harris" wrote in message
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"WeatherGuy" wrote:
Thanks for the reply Art, and the link. I have not had the tyre off the
rim since before I purchased the bike

Just so we can better understand the problem, approximately when was the
bike made? And what type of bike is it (road, moutain bike, etc.). Has it
been unused for a number of years?

foot pump - never compressed air pumps - and a standard car-type pressure
gauge.

Does the tube have a schaeder valve (like on a car)? Assuming the the
gauge is accurate, and the tire was properly seated on a hook bead rim,
this blowout is indeed puzzling.

But my question is - why would this happen after having ridden the bike
for an hour and then put it away for 30 minutes.

I can't answer that. Consider yourself very lucky!

Are there such things as defective tubes?

This was not the fault of the tube.

Should I reduce pressure to 80 PSI in the future?

I would first remove the tire and tube. Inspect the rim to see if has a
hook shape where it grips the tire bead. If it doesn't, then it's probably
an older type rim and you should reduce pressure. Is this the original
tire and wheel that came with the bike when new?

Also check that the rim hasn't been dented by hitting a pothole or curb.

Art Harris


Thanks Art and every one else who contributed. I will write this incident
off as a fluke for now, since the bike is only one month old and of course
has the original tyre and wheel. My LBS replaced the tube today and
inspected the rim. Thanks to all you fine people, I know probably have
enough information to work with if it happens again.

Mike

I'm surprised I didn't see this anywhere else, but maybe I'm the only
person dumb enough to pull this stunt: was the tube the right size for
the tire? If the tire is 700x28 and the tube is good up to only
700x25, for example, the tube will have to be over-inflated to get the
pressure up. I did this once with a 26x1.25 (max) tube in a 26x1.5
ti BANG! (That's the sound of me learning always to check the $#@!
label.)

I'll bet yours would've popped before you even got on the bike (and not
20K later) if you had really made that kind of mistake; but it's worth
remembering to match your tubes and tires.

-JR

"SlowRider" wrote in message
oups.com...
I'm surprised I didn't see this anywhere else, but maybe I'm the only
person dumb enough to pull this stunt: was the tube the right size for
the tire? If the tire is 700x28 and the tube is good up to only
700x25, for example, the tube will have to be over-inflated to get the
pressure up. I did this once with a 26x1.25 (max) tube in a 26x1.5
ti BANG! (That's the sound of me learning always to check the $#@!
label.)

A 700x25 tube in a 700x28 tire is not a big deal. All that happens when you
put in an undersized tube is that it has to stretch a little more to fill
out the inside of the tire. This means that on a smaller tube, the rubber
is effectively a little thinner than it would be on a larger tube. Thinner
rubber is a little more susceptible to punctures, and will have to be topped
up with air a little more often. It cannot and does not make blowouts any
more likely.

Blowouts are caused by incorrect seating of the tire bead on the rim.