The physics of a puncture

Sooty09 · Jun 4, 2017

Anybody who has tried to push a reamer through a nail hole in a tyre wil know how difficult it is yet screw and nails somehow jump up and stand at just the right angle to punch streight through. We have just had the third rear puncture this year on my wife's F700 (always managed to get home due to the tubeless wheels) I have had one in my F800GS and needed RAC recovery.
Dose anybody know if the wheelbase and speed a bike travels has any bearing on the chances of a puncture.

flatdog · Jun 4, 2017

..... is she fat?

Micky · Jun 4, 2017

Sooty09 said:
Anybody who has tried to push a reamer through a nail hole in a tyre wil know how difficult it is yet screw and nails somehow jump up and stand at just the right angle to punch streight through. We have just had the third rear puncture this year on my wife's F700 (always managed to get home due to the tubeless wheels) I have had one in my F800GS and needed RAC recovery.
Dose anybody know if the wheelbase and speed a bike travels has any bearing on the chances of a puncture.

It's all down to luck ... good or bad ...

... as with everything else

Chicken · Jun 4, 2017

flatdog said:
..... is she fat?

Or just HEAVY

steve hughes · Jun 4, 2017

I remember an IAM person advising you get more punctures in the rain as the water lubricates the nail tyre interface.

Silly question but what is her positioning on the road? Does she hug the kerb. Another factor is where she parks, our neighbor is a builder and when he was doing up his house we and our neighbors suffered with punctures.

Rushy · Jun 4, 2017

Chicken said:
Or just HEAVY

The correct term is "big boned "

Only one puncture in 32 yrs of biking and that was a very slow puncture on a big trip, I just pumped it up once every couple of days for the next week and a half. I reckon I've covered around 175k miles in the past 15 yrs so very lucky really.

Santa-2512 · Jun 4, 2017

What i cant understand is,

if you drop a screw or nail it lies flat to the floor.. yet they can punch vertically through a tyre?

Chalky723 · Jun 4, 2017

I went through a phase of getting punctures a few years back, I try to keep away from kerbs & central "crap collections" if possible & (touch wood) have been OK for the past couple of years...

D

Chalky723 · Jun 4, 2017

Santa-2512 said:
What i cant understand is,

if you drop a screw or nail it lies flat to the floor.. yet they can punch vertically through a tyre?

I wonder if the front wheel flicks them up so they're not flat when the rear goes over, or maybe the edge of the tyre tread flicks it up into the gap between treads? The tip of a nail at 30mph would probably punch through things a lot tougher than a tyre....

D

DC · Jun 4, 2017

Chalky723 said:
I wonder if the front wheel flicks them up so they're not flat when the rear goes over, or maybe the edge of the tyre tread flicks it up into the gap between treads? The tip of a nail at 30mph would probably punch through things a lot tougher than a tyre....

D

you have hit the nail on the head .......see what I did there ? coat.... door ...gone

Ogmios · Jun 4, 2017

steve hughes said:
I remember an IAM person advising you get more punctures in the rain as the water lubricates the nail tyre interface.

Silly question but what is her positioning on the road? Does she hug the kerb. Another factor is where she parks, our neighbor is a builder and when he was doing up his house we and our neighbors suffered with punctures.

Not silly at all.
I heard "ghost islands" (all paint / no kerbs) once described as
'a large area of tarmac dedicated to the gathering of punctures!'
seems about right!

Sooty09 · Jun 4, 2017

Ogmios said:
Not silly at all.
I heard "ghost islands" (all paint / no kerbs) once described as
'a large area of tarmac dedicated to the gathering of punctures!'
seems about right!

Very true statement, when walking at lunch time we cross over several traffic islands and roundabouts near a motorway, the hatched zones are full of grit, nails and screws (and a set of disk pads). We try to avoid them but occasionally have to run into these zones when filtering through heavy traffic. Three punctures on one bike in a year is a record for us, between my wife and I we have covered over 859000 miles and only had a few stoppers (Bloody inner tubes).

Chalky723 · Jun 4, 2017

DC said:
you have hit the nail on the head .......see what I did there ? coat.... door ...gone

Arf!

D

Ogmios · Jun 4, 2017

While marshalling a charity run i was overtaking a participant - he was on a ghost island / i was just to his right and behind.
His rear wheel threw up something small and dense. It hit my headlight :blast

/ i ducked just in case :eek

.
For the rest of that weekend my Guzzi had medical tape holding the glass together.

... wasn't worth getting a genuine replacement glass.
So now, i've probably the only Guzzi Cali 3 FF with a Toyota Hiace headlamp

instead of the standard copy of a Fiat Bambino one

.

~~

SuperTed · Jun 5, 2017

Chalky723 said:
I wonder if the front wheel flicks them up so they're not flat when the rear goes over, or maybe the edge of the tyre tread flicks it up into the gap between treads? The tip of a nail at 30mph would probably punch through things a lot tougher than a tyre....

D

Yep, that's exactly what happens. Particularly with a bike like the GS with a comparatively short wheel base the front makes the offending screw/nail/rivet/whatever stand-up ready to punch through the rear tyre. I've had a few over the years and it has never been the front tyre that suffers. With a tubeless tyre if you find something like a screw in it Rule One is: Don't Take It Out. It's doing a really good job of bunging up the hole, so leave it where it is. Ride to your preferred dealer or tyre fitter, make sure they can fix the puncture / replace the tyre, then take it out. This doesn't work with a tubed tyre.

The physics of a puncture

Sooty09

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flatdog

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Micky

Never knowingly understood

Chicken

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steve hughes

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Rushy

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Santa-2512

Omnipotent one

Chalky723

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Chalky723

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DC

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Ogmios

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Sooty09

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Chalky723

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Ogmios

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SuperTed

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