Have you ever had a puncture in the front tire?

I have a friend who just got a nail in his rear tire, and he wondered aloud how, after 30 years of riding, he has never gotten a nail in the front tire. He has had lots of punctures in the rear tire, but never the front.

Naturally, with a PhD in Mechanical Engineering, his mind is going nuts right now trying to figure out why this would be, but in the meantime I thought I would post a quick poll and see what your experiences are.

Have you ever had a puncture in the front tire? How often do you get a puncture in the front relative to the rear?

Also, post a tally of total punctures and where they were and I'll crunch the data.

Never in the front, but I've gotten 2 in the rear in the last year.

I'm declining to say on the grounds of not wanting to tempt fate.

I think usually the front makes the nail/screw/evil tire puncturing device stand up and then it sinks into the rear tire. I had one small leak in the front of an old tire that I never figured out what it was, and two screws in the rear.

so mostly rear tire.

I can't really remember any pucctures in my tires, but the rear is wider, so odds would be greater of picking up a nail, etc. But then again, the front should pick it up and clear the way for the rear.......who knows

madmanmaigret said:

I think usually the front makes the nail/screw/evil tire puncturing device stand up and then it sinks into the rear tire.

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That's exactly what my friend is thinking.

It makes sense, if I have a nail laying on the ground, it's going to lay flat. If I bounce a basketball on it, it will probably never puncture the ball. But if I bounce a basketball on it, then follow that with another basketball, the first one could pop the nail up off the ground, then some nonzero percentage of the time, the nail will be aimed perfectly upward and puncture the second ball.

I haven't gotten either yet (knock on wood) but in seeing posts on both forums, my unscientific assessment is that it looks to me like the rear falls victim more often than the front.

I suspect as you do that the front tire pops it up, but I'm guessing there's time and directional components as well. With your basketball thought-experiment, you can only drop the second basketball on it so quickly. The first ball would have to stand it up "aimed perfectly upward" so it doesn't fall over before you can drop the second ball. So, it would eventually position itself correctly, but it would take a while.

In contrast, a motorcycle or car tire follows the front tire just a fraction of a second behind. While the nail or screw is in motion, if the business end is pointing anywhere in the vicinity of the rear of the bike (rather than pointing at just the right angle) I suspect it can be caught in the rubber or tread pattern and smashed into place as the tire rolls down on it.

So for your thought-experiment, imagine you could throw basketball #1 with basketball #2 a fraction of a second behind the first, and were able to throw (or preferably, roll) both at highway speeds.

Now it doesn't seem quite so improbable. :Flash:

FizzySix said:

I haven't gotten either yet (knock on wood) but in seeing posts on both forums, my unscientific assessment is that it looks to me like the rear falls victim more often than the front.

I suspect as you do that the front tire pops it up, but I'm guessing there's time and directional components as well. With your basketball thought-experiment, you can only drop the second basketball on it so quickly. The first ball would have to stand it up "aimed perfectly upward" so it doesn't fall over before you can drop the second ball. So, it would eventually position itself correctly, but it would take a while.

In contrast, a motorcycle or car tire follows the front tire just a fraction of a second behind. While the nail or screw is in motion, if the business end is pointing anywhere in the vicinity of the rear of the bike (rather than pointing at just the right angle) I suspect it can be caught in the rubber or tread pattern and smashed into place as the tire rolls down on it.

So for your thought-experiment, imagine you could throw basketball #1 with basketball #2 a fraction of a second behind the first, and were able to throw (or preferably, roll) both at highway speeds.

Now it doesn't seem quite so improbable. :Flash:

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Thanks for the analysis. I agree that it doesn't seem improbable. My point wasn't that the chances were diminishingly low, but the other way around.

Laying on its side, a nail is almost certain to not puncture a front tire. Once it is disturbed by the front, it can be put into any position, and the possibility of piercing the rear is much higher. I just didn't state it as eloquently as you

How can this not already be analyzed by some geek with too much time on his/her hands? I'm going to search around on the intertubes to see if someone has done a real analysis or experiment to check this out. Maybe, if it hasn't been done yet, I'll submit the experiment idea to those guys who have a whole show dedicated to slow-motion cameras...

CHEMIKER said:

Maybe, if it hasn't been done yet, I'll submit the experiment idea to those guys who have a whole show dedicated to slow-motion cameras...

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I want that job someday...

I keep waiting for someone to say they only get nails in the rear tire because that's the only one they ride on - the front is usually in the air.

I found this on a bicycle message board:

"Many sharp objects, especially those that lie flat on the road like
nails and pieces of metal, more often enter rear tires than the front
tires. That is because the front tire upends them just in time for
the rear tire to be impaled on them.

For example, nails seldom enter front tires. When dropped from a
moving vehicle, nails slide down the road, and align themselves
pointing toward traffic, because they prefer to slide head first as
they would when laid on a slope. The front tire rolling over such a
lengthwise nail, can tilt it up just in time for the rear tire to
encounter it on end. I once got a flat from a one inch diameter steel
washer that the front tire had flipped up so that the rear tire struck
it on edge. When following another wheel closely, the front tire can
get the "rear tire" treatment from the preceding wheel.

The front wheel set-up effect is especially true for "Michelin" wires,
the fine strands of stainless wire that make up steel belts of auto
tires. These wires, left on the road when such tires exposes their
belt, cause hard to find slow leaks almost exclusively in rear tires.

When wet, glass can stick to the tire even in the flat orientation and
thereby get a second chance when it comes around again. To make
things worse, glass cuts far more easily when wet as those who have
cut rubber tubing in chemistry class may remember. A wet razor blade
cuts latex rubber tubing in a single slice while a dry blade only
makes a nick."

This is posted by a man named Jobst Brandt, the author of "The Bicycle Wheel". He's a mechanical engineer out of Stanford, and has been an avid bicyclist for a long time, so I believe his assessment.

I got one in the rear 2 weeks ago,damn tyre only had 4,500k's on it too :spank:

CHEMIKER said:

I found this on a bicycle message board:

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Interesting! I have no idea why this thread fascinates me, other than I'm a nerd... :tard:

I would guess that we get the same effect from hard objects like nails, but given that our rear tires are spinning way faster than a bicycle wheel (and heavier, possibly crushing the glass, with thicker tires to boot), I would have to imagine they have a greater tendency to fling off glass than run over it again.

Thoughts?

fast blue one said:

I'm declining to say on the grounds of not wanting to tempt fate.

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At least for the front.....yes, I got one on the rear not too long ago. So much for squeezing 17k miles on that tire.