Front blowout

"Bob Shanteau" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Last week a friend was following me at about 30 mph down a gentle hill on our road bikes, when I
heard the sounds of a blowout and a crashing bike behind me. When I went back to check, I found
him on the ground, out cold, breathing heavily and bleeding from the mouth. It was evident that he
had hit the asphalt pavement hard with the left rear of his head. His helmet appears to have taken
much of the blow, as there were pieces of foam

broken

Quoted message said:

off. He was taken to the hospital and is still there a week later. The doctors say he will
recover, but it will take a while.

I did not see him fall, and there was nobody else around. When I inspected his front wheel, I
found that his clincher tire was completely separated from the rim and his tube was wrapped around
the hub at one end and caught on a brake pad at the other. There was a spot on the tire where the
tread had worn almost completely off, otherwise the tire was in good shape. The rim was scraped
all the way around, but there was no spot that was much worse than the rest. The tube was split
where the bead had been and the

tire

Quoted message said:

had no holes in it, so it was evident that the bead had come loose from

the

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rim, allowing the tube to blow out. I think my friend had fixed a flat on his front tire a few
months ago. He must not have seated the tire

correctly.

Quoted message said:

My question is about the mechanics of the fall. It seems to me that he

must

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have taken a header over the handlebars. That would only happen if his

front

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wheel had stopped. His knuckles are scraped, especially on his left hand,

as

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though his hands were still on the hoods when he hit the ground. I don't

see

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that the wheel could have stopped with the tire off the rim, as there

would

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be insufficient friction between a bare rim and the pavement to stop the wheel. So the tire
must have been on the rim when the wheel stopped and it somehow came loose from the rim during
the fall.

When I first started riding some 30 years ago, I had an improperly glued tubular tire come loose
on my front wheel while in a practice sprint. The wheel stopped when the tire became lodged
between the fork blade and the rim. I took a header and landed on the right side of my head. I was

wearing

Quoted message said:

a hairnet helment and suffered a slight concussion, but nothing as serious as my friend has. Until
his fall, I didn't realize it was possible to

suffer

Quoted message said:

severe injuries to the head from taking a header on pavement.

I have two questions:

If a stopped tire caused my friend's fall, what might have caused the tire come loose from the rim
during the fall?

Also, has anyone else seen such a severe head injury from taking a header onto pavement?

His tube/tire may have gotten stuck in the brakes. That'll stop a wheel quickly.

I don't have any front teeth from a bicycle crash when I was 15. That count?

Mike

"Bob Shanteau" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Also, has anyone else seen such a severe head injury from taking a header onto pavement?

Sounds like an invitation to another helmet thread - the helmet probably saved his life, no, it
probably caused his injury either through risk compensation or cranial rotation... etc. etc. Why
should it be surprising that hitting your head on the pavement can cause severe head injury?

Rich

A special feature of front blowouts, at least with wide tires, is that balance corrections reverse;
if you steer right, it steers the loose tire casing left, and you go over faster than if you hadn't
corrected at all. So if you have a front blowout, at least on wide tires, stop very fast. I don't
recall any similar difficult on narrow tires. The fall though is to the side, not over the
handlebars, at least not a first. I suppose you could wind up in front of the bike though.
--
Ron Hardin [email hidden]

On the internet, nobody knows you're a jerk.

"Bob Shanteau" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Also, has anyone else seen such a severe head injury from taking a header onto pavement?

Last year a local (MA) rider (helmeted) died in a similar fall. The theory was that he threw a
chain, causing the rear wheel to skid and eventually crash. As in your case, there was another
cyclist riding with, but not closely, and the deceased rider was going downhill pretty fast at the
time of the crash.

In article <vSxtb.3838$6G3.2069@fed1read06>,

Mike S.' mikeshaw2@coxDOTnet said:

"Bob Shanteau" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Last week a friend was following me at about 30 mph down a gentle hill on our road bikes, when I
heard the sounds of a blowout and a crashing bike behind me. When I went back to check, I found
him on the ground, out cold, breathing heavily and bleeding from the mouth. It was evident that
he had hit the asphalt pavement hard with the left rear of his head. His helmet appears to have
taken much of the blow, as there were pieces of foam

broken

Quoted message said:

off. He was taken to the hospital and is still there a week later. The doctors say he will
recover, but it will take a while.

I did not see him fall, and there was nobody else around. When I inspected his front wheel, I
found that his clincher tire was completely separated from the rim and his tube was wrapped
around the hub at one end and caught on a brake pad at the other. There was a spot on the tire
where the tread had worn almost completely off, otherwise the tire was in good shape. The rim
was scraped all the way around, but there was no spot that was much worse than the rest. The
tube was split where the bead had been and the

tire

Quoted message said:

had no holes in it, so it was evident that the bead had come loose from

the

Quoted message said:

rim, allowing the tube to blow out. I think my friend had fixed a flat on his front tire a few
months ago. He must not have seated the tire

correctly.

Quoted message said:

My question is about the mechanics of the fall. It seems to me that he

must

Quoted message said:

have taken a header over the handlebars. That would only happen if his

front

Quoted message said:

wheel had stopped. His knuckles are scraped, especially on his left hand,

as

Quoted message said:

though his hands were still on the hoods when he hit the ground. I don't

see

Quoted message said:

that the wheel could have stopped with the tire off the rim, as there

would

Quoted message said:

be insufficient friction between a bare rim and the pavement to stop the wheel. So the tire
must have been on the rim when the wheel stopped and it somehow came loose from the rim during
the fall.

When I first started riding some 30 years ago, I had an improperly glued tubular tire come
loose on my front wheel while in a practice sprint. The wheel stopped when the tire became
lodged between the fork blade and the rim. I took a header and landed on the right side of my
head. I was

wearing

Quoted message said:

a hairnet helment and suffered a slight concussion, but nothing as serious as my friend has.
Until his fall, I didn't realize it was possible to

suffer

Quoted message said:

severe injuries to the head from taking a header on pavement.

I have two questions:

If a stopped tire caused my friend's fall, what might have caused the tire come loose from the
rim during the fall?

Well, it sounds like you nailed the fact that the blowout was caused by a bead separation (Jobst
would approve, having previously claimed that explosive blowouts are almost always caused by bead
failures). Once that happens, the tire is de facto loose from the rim, and can do any number of
things, all bad.

A few guesses, though I am not an accident reconstructionist (Jobst has done this very job, so he
probably knows with fair certainty what did happen):

the worn spot on the tire means the wheel spent a short time locked in place, sliding on that part
of the tire. I guess at one of two causes:

1) your friend reacted to the blowout by grabbing the front brake. Tire locked up, and over he went.

Quoted message said:

His tube/tire may have gotten stuck in the brakes. That'll stop a wheel quickly.

2) Yeah, your friend's tube separated from the wheel, got caught on the hub and brake just as you
found it, and stopped the bike dead. Er, near-dead. Tire, already semi-loose, locked up and
over he went.

He could well have been on the hoods the whole time, as the accident probably happened so fast he
had no time to react. You just end up on your face practically before you know there's a problem.
Note that in this kind of accident, you can actually hit the ground with more speed than mere
acceleration due to dropping from the height of your head (maybe 5 feet or so) to the ground would
indicate, because as the wheel locks up, you effectively get most or all of your forward speed
translated into rotation of the bike around the now-locked wheel, slamming you into the ground at
something very close to the bike's former speed.

Quoted message said:

Quoted message said:

Also, has anyone else seen such a severe head injury from taking a header onto pavement?

Close. My father got knocked off his bike many years ago, and ended up landing helmet-first on the
pavement. He got away with a broken finger, shock, and persistent numbness in part of his face,
evidence of nerve damage from the accident. I gather he was fairly weird for the rest of the day,
though my mother sometimes suggest he's been fairly weird for the whole time she's known him.

Bathtub falls have been known to cause fatal head injuries, and many drops to pavement are in the
same range of forces. Accidents like this are interesting in their effects on the body and whatnot
because you just don't experience the violent forces of a bike accident or road accident (especially
a car accident) in ordinary life. Weird stuff happens, and the forces you get can be very
unpredictable. I've taken some headers nearly that violent, though usually at lower speeds than 30
mph, and mostly walked away with minimal trauma (took a mountain-bike handlebar in the gut one time,
which made the rest of the bike race fairly slow; won "most blood" at another race). OTOH, catch
things just the wrong way and you can break your neck. Racing cyclists can and have died even with
helmets on, just thanks to the bad fortune to crash the wrong way in the wrong place.

Since this is already close to being a helmets thread, how about a bent-vs-DF thread instead?
Richard Ballantine of "Richard's Bicycle Book" has gone so far as to claim that recumbents are a bit
safer than upright bikes because you tend to arrive at accidents feet first, low, and with a bike
structure ahead of your head and torso, rather than head first, high, and with very little in front
of you. (I'm paraphrasing and interpolating his argument, which was framed around an anecdote about
a friend having a very bad crash in a recumbent crit while riding a faired trike)

--
Ryan Cousineau, [email hidden] sfu.ca~rcousineOpen ↗ President, Fabrizio Mazzoleni Fan Club

RE/

Quoted message said:

Also, has anyone else seen such a severe head injury from taking a header onto pavement?

A drunk sideswiped me on my Yamaha YDS-6. The bike went endo and I did a sort of swan dive onto the
blacktop. I was doing about 45 when he hit me.

Cracked a perfectly-good Bell helmet, and I saw flashes of light intermittantly for several days.

Also, I suspect I put my dentist's kid through college....
--
PeteCresswell

Sweeping right turn, gradual descent, going about 25 mph... front tire blew throught a 4-5 cm gash
on its right sidewall cut by a curved piece of razor-sharp Budweiser bottle I hadn't seen.

I slowed and stopped safely, but with a scare. What surprised me most, and what I still remember,
was the bike's tendency to straighten out when the tire blew. I actually let it cross the yellow
line into the oncoming lane rather than wrestle with it (luckily no traffic).

This was on a road bike with 23 mm tires on MA-2 rims. The bead stayed on.

Mike Yankee

(Address is munged to thwart spammers. To reply, delete everything after "com".)

shantes-<< Last week a friend was following me at about 30 mph down a gentle hill on our road bikes,
when I heard the sounds of a blowout and a crashing bike behind me. When I went back to check, I
found him on the ground, out cold, breathing heavily and bleeding from the mouth. It was evident
that he had hit the asphalt pavement hard with the left rear of his head. His helmet appears to have
taken much of the blow, as there were pieces of foam broken off. He was taken to the hospital and is
still there a week later. The doctors say he will recover, but it will take a while.

I did not see him fall, and there was nobody else around. When I inspected his front wheel, I found
that his clincher tire was completely separated from the rim and his tube was wrapped around the hub
at one end and caught on a brake pad at the other. There was a spot on the tire where the tread had
worn almost completely off, otherwise the tire was in good shape.

Quoted message said:

Quoted message said:

<BR><BR>

another reason to use tubulars...

C'mon, don't get excited, it's nearly winter and it's tiime for this type of discussion..

BTW-hope your friend finds a good Neuro and a good Clinical Psych if he needs eval and brain trama
retraining, like I did/do..hope he recovers well.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali costruite eccezionalmente bene"

Mike S. said:

His tube/tire may have gotten stuck in the brakes. That'll stop a wheel quickly.

Seconded. Incidentally, on a clincher tyre, where it's almost impossible to make the tyre slip
around the rim, the mode of failure is often that the wheel locks and bends the fork backwards so
the wheel hits the downtube. The net effect on the rider is the same :-(

Ryan Cousineau said:

... Note that in this kind of accident, you can actually hit the ground with more speed than mere
acceleration due to dropping from the height of your head (maybe 5 feet or so) to the ground would
indicate, because as the wheel locks up, you effectively get most or all of your forward speed
translated into rotation of the bike around the now-locked wheel, slamming you into the ground at
something very close to the bike's former speed.

I don't think this is true. The vertical component of speed is the same as in a stationary 5
foot drop.

For your effect to work, the front wheel would have to somehow be tied to the ground, and the rider
tied to the bike. That is, the wheel and bike frame would have to exert tension on the rider's body,
to pull him into a vertical circular arc.

The horizontal component of your original speed (minus a bit for whatever braking took place) has to
be added vectorially to the "5 foot drop" speed, but that's not the same thing as what you're
describing.

Quoted message said:

Since this is already close to being a helmets thread, how about a bent-vs-DF thread instead?
Richard Ballantine of "Richard's Bicycle Book" has gone so far as to claim that recumbents are a
bit safer than upright bikes because you tend to arrive at accidents feet first, low, and with a
bike structure ahead of your head and torso, rather than head first, high, and with very little in
front of you.

Not to mention that the recumbent rider is likely to be going much slower.

There, that should do it! ;-)

--
Frank Krygowski

"frkrygowHALTSPAM" <"frkrygowHALTSPAM"@cc.ysu.edu> wrote in message "]news:[email hidden]...

Quoted message said:

Ryan Cousineau said:

... Note that in this kind of accident, you can actually hit the ground with more speed than
mere acceleration due to dropping from the height of your head (maybe 5 feet or so) to the
ground would indicate, because as the wheel locks up, you effectively get most or all of your
forward speed translated into rotation of the bike around the now-locked wheel, slamming you
into the ground at something very close to the bike's former speed.

I don't think this is true. The vertical component of speed is the same as in a stationary 5
foot drop.

For your effect to work, the front wheel would have to somehow be tied to the ground,

The tire has possibly frozen up due to the tire getting stuck in the break and had skidded causing a
bald spot on the tire. That's approximately "tied to the ground."

Quoted message said:

and the rider tied to the bike.

You mean, like gripping the handlebars?

Shayne Wissler

In article said:

Ryan Cousineau said:

... Note that in this kind of accident, you can actually hit the ground with more speed than
mere acceleration due to dropping from the height of your head (maybe 5 feet or so) to the
ground would indicate, because as the wheel locks up, you effectively get most or all of your
forward speed translated into rotation of the bike around the now-locked wheel, slamming you
into the ground at something very close to the bike's former speed.

I don't think this is true. The vertical component of speed is the same as in a stationary 5
foot drop.

For your effect to work, the front wheel would have to somehow be tied to the ground, and the
rider tied to the bike. That is, the wheel and bike frame would have to exert tension on the
rider's body, to pull him into a vertical circular arc.

You're right. I started a long rebuttal, but as far as I can tell, it proved you correct.

Quoted message said:

The horizontal component of your original speed (minus a bit for whatever braking took place) has
to be added vectorially to the "5 foot drop" speed, but that's not the same thing as what you're
describing.

Yes. It should be said that taking this angled vector into the pavement just isn't going to be good
for you 🙂.

Quoted message said:

Quoted message said:

Since this is already close to being a helmets thread, how about a bent-vs-DF thread instead?
Richard Ballantine of "Richard's Bicycle Book" has gone so far as to claim that recumbents are a
bit safer than upright bikes because you tend to arrive at accidents feet first, low, and with a
bike structure ahead of your head and torso, rather than head first, high, and with very little
in front of you.

Not to mention that the recumbent rider is likely to be going much slower.

There, that should do it! ;-)

--
Ryan Cousineau, [email hidden] sfu.ca~rcousineOpen ↗ President, Fabrizio Mazzoleni Fan Club

Shayne Wissler said:

"frkrygowHALTSPAM" <"frkrygowHALTSPAM"@cc.ysu.edu> wrote in message "]news:[email hidden]...

Quoted message said:

Ryan Cousineau said:

... Note that in this kind of accident, you can actually hit the ground with more speed than
mere acceleration due to dropping from the height of your head (maybe 5 feet or so) to the
ground would indicate, because as the wheel locks up, you effectively get most or all of your
forward speed translated into rotation of the bike around the now-locked wheel, slamming you
into the ground at something very close to the bike's former speed.

I don't think this is true. The vertical component of speed is the same as in a stationary 5
foot drop.

For your effect to work, the front wheel would have to somehow be tied to the ground,

The tire has possibly frozen up due to the tire getting stuck in the break and had skidded causing
a bald spot on the tire. That's approximately "tied to the ground."

Not in the vertical direction.

--
Benjamin Lewis

Clothes make the man. Naked people have little or no influence on society.
- Mark Twain

Shayne Wissler said:

The tire has possibly frozen up due to the tire getting stuck in the break and had skidded causing
a bald spot on the tire. That's approximately "tied to the ground."

No, it isn't. It will exert a very large horizontal force component (reducing forward velocity), but
unless the rubber has melted and formed a glue bond with the pavement it will not exert a signficant
downward force on the bike, which is what would be needed for the pendulum effect to happen.

Chris
--
Chris Colohan Email: [email hidden] PGP: finger [email hidden] Web: www.colohan.com Phone:
(412)268-4751

"Benjamin Lewis" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Shayne Wissler said:

"frkrygowHALTSPAM" <"frkrygowHALTSPAM"@cc.ysu.edu> wrote in message
"]news:[email hidden]...

Quoted message said:

Ryan Cousineau wrote:
> ... Note that in this kind of accident, you can actually hit the ground with more speed than
> mere acceleration due to dropping from the height of your head (maybe 5 feet or so) to the
> ground would indicate, because as the

wheel

Quoted message said:

Quoted message said:

Quoted message said:

> locks up, you effectively get most or all of your forward speed translated into rotation of
> the bike around the now-locked wheel, slamming you into the ground at something very close to
> the bike's former speed.

I don't think this is true. The vertical component of speed is the

same

Quoted message said:

Quoted message said:

Quoted message said:

as in a stationary 5 foot drop.

For your effect to work, the front wheel would have to somehow be tied to the ground,

The tire has possibly frozen up due to the tire getting stuck in the break and had skidded
causing a bald spot on the tire. That's approximately "tied to the ground."

Not in the vertical direction.

The bicycle is in effect, approximately vertically tied due to its inertia and weight. If the rider
held the handlebars while quickly going over, there would be some effect of his forward motion being
translated into a forceful throwing of the rider into the ground--worse than a stationary 5-foot
drop. How much worse would depend on a lot of particulars.

Shayne Wissler

"Christopher Brian Colohan" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Shayne Wissler said:

The tire has possibly frozen up due to the tire getting stuck in the

break

Quoted message said:

Quoted message said:

and had skidded causing a bald spot on the tire. That's approximately

"tied

Quoted message said:

Quoted message said:

to the ground."

No, it isn't. It will exert a very large horizontal force component (reducing forward velocity),

Throwing the rider over the handlebars...

Quoted message said:

but unless the rubber has melted and formed a glue bond with the pavement it will not exert a
signficant downward force on the bike,

The friction of the tire won't directly create more downward force, but the weight and inertia of
the bike will--if the rider keeps holding onto the handlebars.

Shayne Wissler

Thanks to those who have offered their own stories of doing headers onto pavement. I see that fate
plays a large part in the extent of the injury. I do note, however, that most of the stories are of
face plants rather than impact to the right or left rear of the head.

Peter Chisolm noted, "another reason to use tubulars."

When I raced, everybody I competed with used tubular tires. I still ride tubulars and have never
had a blowout, only slow or fast leaks. Even with fast leaks, I have always been able to keep
control of the bicycle. The only tubular tire blowout I have seen was on the banking of a track
where the rider, who was going relatively slowly, simply slid down the banking. I cannot picture a
situation where a front blowout with a tubular would cause a rider to go over the handlebars. With
the tire glued to the rim, there is nothing to jam between the frame and the wheel to cause the
wheel to stop. A rider may lose control and go down, but the fall would be to the side instead of
over the bars.

I am familiar with most of the arguments regarding tubulars vs. clinchers and the fact that the
arguments have been repeated many times in this newsgroup, but the avoidance of a header with a
blown front tubular is a new one on me.

So that brings up a couple of questions:

If my friend had been riding tubulars and had a front blowout, would he still have lost control of
the bicycle?

If so, is there any possibility he would have gone over the handlebars?

Shayne Wissler said:

"Benjamin Lewis" <[email hidden]> wrote in message "]news:[email hidden]...

Quoted message said:

Shayne Wissler said:

"frkrygowHALTSPAM" <"frkrygowHALTSPAM"@cc.ysu.edu> wrote in message
"]news:[email hidden]...
> Ryan Cousineau wrote:
>> ... Note that in this kind of accident, you can actually hit the ground with more speed than
>> mere acceleration due to dropping from the height of your head (maybe 5 feet or so) to the
>> ground would indicate, because as the

wheel

Quoted message said:

Quoted message said:

>> locks up, you effectively get most or all of your forward speed translated into rotation of
>> the bike around the now-locked wheel, slamming you into the ground at something very close to
>> the bike's former speed.
>
> I don't think this is true. The vertical component of speed is the

same

Quoted message said:

Quoted message said:

> as in a stationary 5 foot drop.
>
> For your effect to work, the front wheel would have to somehow be tied to the ground,

The tire has possibly frozen up due to the tire getting stuck in the break and had skidded
causing a bald spot on the tire. That's approximately "tied to the ground."

Not in the vertical direction.

The bicycle is in effect, approximately vertically tied due to its inertia and weight.

Unless the bicycle is physically tied to the ground, the only downward force on the centre of mass
of the bicycle+rider will be due to gravity. I guess there could be an increased downward force on
the rider if the centre of mass of the bicycle moves upward and the rider grips the bicycle tightly,
but I suspect if this effect were significant the rider would tend to let go. In any case, the mass
of the bicycle is often an order of magnitude smaller than the mass of the rider.

--
Benjamin Lewis

Clothes make the man. Naked people have little or no influence on society.
- Mark Twain

Shayne Wissler said:

Quoted message said:

I don't think this is true. The vertical component of speed is the same as in a stationary 5
foot drop.

He's right. Unless the rider is secured to the axle of the wheel somehow, he is not going to fall
downward faster than gravity dictates. Parts of the bike might hit the ground harder, since they are
attached to the wheel, but the rider would lag behind. That much shock and the rider would lose his
grip on the bars, and his pedals would disengage. He then falls to the ground.

Of course, the damage of the impact would also include the forward component of velocity at impact.
That's why you scrape off more skin when you crash from a higher speed. This does not affect the
force of the impact on the head on a flat road, but would make things worse if he hit something
else as well.

--

David L. Johnson

__o | What is objectionable, and what is dangerous about extremists is _`\(,_ | not that they are
extreme, but that they are intolerant. (_)/ (_) | --Robert F. Kennedy