Frame failure (with pictures)

are you saying the downtube snapped because the front wheel locked up, or because the wheel jammed so hard that it hit the downtube; or because the piece of car tyre hit the downtube?

when you say he fell victum to a low spoke count, are you suggesting that the piece of tyre wouldn't have got stuck in a 32 spoke wheel?

I'm a little unclear on this 🙂

531Aussie said:

are you saying the downtube snapped because the front wheel jammed, or
because the wheel jammed so hard that it hit the downtube?

The latter. We've all seen intact alu/steel frames that can/will impact the
front wheel.
--
Phil

Phil said:

We were on our fast club ride this past Thursday. The trailing rider fell
victim to low-spoke-count wheels and a separated tire tread on the side of
the road.

Quoted message said:

The piece of tire tread (about 2 feet long, and roughly 8 inches wide) may
have been kicked up by riders just ahead of him. The separated tread caught
up in the wheel and traveled up to the fork, where it stopped suddenly,
leaving a rubber streak on the back side of the fork well below where the
bicycle tire could have been.

Quoted message said:

Rider sustained some broken facial bones, a concussion, and minor cuts. He
is doing well currently.

This is one of the scary things about pace line riding. A friend had the
same thing this year with a stick (kicked into his front wheel by the
preceding bike). I'm amazed by how few riders seem to be unaware of this
hazard and blithely run over debris when pace lining.

In article <kZtgg.83147$IZ2.3403@dukeread07>,
"Phil, Squid-in-Training" <[email hidden]>

Quoted message said:

531Aussie said:

are you saying the downtube snapped because the front wheel jammed,
or because the wheel jammed so hard that it hit the downtube?

The latter. We've all seen intact alu/steel frames that can/will
impact the front wheel.

Well, that's the thing. Metal bends. Carbon fiber breaks. I hope the
rider heals up well. Broken facial bones can make eating a painful deal
for a long time.

Phil said:

Note: linked pictures are rather large

We were on our fast club ride this past Thursday. The trailing rider fell
victim to low-spoke-count wheels and a separated tire tread on the side of
the road.

The same thing happened on a ride I was on. It is basically a freak
accident, the debris in question then was a piece of alu siding, that
just looked like paper on the road.

The fork and front wheel were relatively undamaged, but when the rider
was pitched up the alu frame sheared at the top tube and buckled at the
down tube.

The rider was using low spoke count wheels, so you could argue that
having more spokes may prevent debris from entering your wheel, but
otherwise you can't fault the bike's design or materials.

Tim McNamara said:

Well, that's the thing. Metal bends. Carbon fiber breaks.

Mostly true, but the lightest metal frames would break too -- or bend to
the point of complete collapse, with the same result.

The problem is not the material, but shaving weight to the point where
there's no margin for error.

Matt O.

"Matt O'Toole" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Tim McNamara said:

Well, that's the thing. Metal bends. Carbon fiber breaks.

Mostly true, but the lightest metal frames would break too -- or bend to
the point of complete collapse, with the same result.

The problem is not the material, but shaving weight to the point where
there's no margin for error.

Matt O.

I'm not sure how a lightweight frame snapping is less good than a heavy
frame buckling. A stick through the spokes (however many) still sends you
flying over the bars and likely writes-off the frame. It is thankfully rare
for things to go through the spokes, but when it does it's typically rider
launch time.

I've seen 'chunky' steel frames with bent forks and strangely steep head
angles.

Skippy
E&OE

On 4 Jun 2006 08:52:04 -0700, [email hidden] wrote:

[snip]

Quoted message said:

The same thing happened on a ride I was on. It is basically a freak
accident, the debris in question then was a piece of alu siding, that
just looked like paper on the road.

The fork and front wheel were relatively undamaged, but when the rider
was pitched up the alu frame sheared at the top tube and buckled at the
down tube.

The rider was using low spoke count wheels, so you could argue that
having more spokes may prevent debris from entering your wheel, but
otherwise you can't fault the bike's design or materials.

There have been a number of times recently that I've had something (a
branch, usually) slap against the side of a wheel and get knocked away
without damage. On the other hand, the number of times that I've had
something get jammed in the spokes is very small; just twice, in 40+
years of riding 36-spoke wheels. The only spokejams I've seen in
person in the past several years were both on low-count wheels. (Not
mine, naturally.) For some time, and for multiple reasons, I have
been of the opinion that low-count wheels are not a good idea for
ordinary riding, and this merely bolsters that impression.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Forks are now much stronger relative to frames than they used to be. If that
had been a steel frame and fork then you would probably have a considerably
bent fork and a few small ripples on the underside of the top and down
tubes. Here you seem to have an undamaged fork and a completely destroyed
frame.

Nick

Werehatrack said:

On 4 Jun 2006 08:52:04 -0700, [email hidden] wrote:

[snip]

Quoted message said:

The same thing happened on a ride I was on. It is basically a freak
accident, the debris in question then was a piece of alu siding, that
just looked like paper on the road.

The fork and front wheel were relatively undamaged, but when the
rider was pitched up the alu frame sheared at the top tube and
buckled at the down tube.

The rider was using low spoke count wheels, so you could argue that
having more spokes may prevent debris from entering your wheel, but
otherwise you can't fault the bike's design or materials.

There have been a number of times recently that I've had something (a
branch, usually) slap against the side of a wheel and get knocked away
without damage. On the other hand, the number of times that I've had
something get jammed in the spokes is very small; just twice, in 40+
years of riding 36-spoke wheels. The only spokejams I've seen in
person in the past several years were both on low-count wheels. (Not
mine, naturally.) For some time, and for multiple reasons, I have
been of the opinion that low-count wheels are not a good idea for
ordinary riding, and this merely bolsters that impression.

Yeah, me too. My road bike came with those same wheels and I chucked 'em.
My 32h do nicely.

Another data point: we were riding at about 27mph at the time, so the energy
dissipated is about 2.5 times more than a typical rider riding at 17mph.

--
Phil

Nick Payne said:

Forks are now much stronger relative to frames than they used to be.
If that had been a steel frame and fork then you would probably have
a considerably bent fork and a few small ripples on the underside of
the top and down tubes. Here you seem to have an undamaged fork and a
completely destroyed frame.

Nick

Yes - as far as I can see, the fork appears untouched, save for the rubber
streak.

One might say, however, that the carbon frame is weaker than a steel frame.
What would happen if the carbon fork were on a steel frame? Would the steel
frame fail similarly? Either way, I don't know.

--
Phil

Phil, Squid-in-Training wrote:

-snip-

Quoted message said:

All downtube portions of the bike were still connected via fibers
immediately after the crash. The top tube was not. The EMTs broke off the
part of the downtube that is separated in the pictures.

-snip-

Phil

Why did the EMTs touch the bike? Was the rider entangled w/ the bike,
or did he launch right over, leaving it behind?

Curious, John

john said:

Phil, Squid-in-Training wrote:

-snip-

Quoted message said:

All downtube portions of the bike were still connected via fibers
immediately after the crash. The top tube was not. The EMTs broke
off the part of the downtube that is separated in the pictures.

-snip-

Phil

Why did the EMTs touch the bike? Was the rider entangled w/ the bike,
or did he launch right over, leaving it behind?

Curious, John

The EMTs were going to take it to the ER with him. They were trying to
store it in the ambulance's side-panel storage, folding the frame over so
the wheels were parallel to each other, thus breaking the downtube fully.
They said, "there's no security for this bike... it will be left outside the
ER where he'll be." I said, "nuh-uh" and called a friend to drive me and
his and my bike back to the bike shop.
--
Phil

Phil said:

Note: linked pictures are rather large

Quoted message said:

We were on our fast club ride this past Thursday. The trailing rider
fell victim to low-spoke-count wheels and a separated tire tread on
the side of the road. .. The piece of tire tread (about 2 feet long,
and roughly 8 inches wide) may have been kicked up by riders just
ahead of him. The separated tread caught up in the wheel and
traveled up to the fork, where it stopped suddenly, leaving a rubber
streak on the back side of the fork well below where the bicycle tire
could have been.

This happens all the time with my steel bike. Sometimes, even
multiple riders get giant chunks of rubber stuck in their wheels.
It's gotten so bad that we even take turns reaching down to grab
chunks of tire rubber and chuck them into each others' 36-count spoke
wheels to see what happens, all the time laughing our heads off at
those silly low-spoke count carbon fiber babies .... as the tire
bounces harmlessly off our 36-spoke wheels ... *grin* ...

- Don Gillies
San Diego, CA

Phil said:

Nick Payne said:

Forks are now much stronger relative to frames than they used to be.
If that had been a steel frame and fork then you would probably have
a considerably bent fork and a few small ripples on the underside of
the top and down tubes. Here you seem to have an undamaged fork and a
completely destroyed frame.

Nick

Yes - as far as I can see, the fork appears untouched, save for the rubber
streak.

One might say, however, that the carbon frame is weaker than a steel frame.
What would happen if the carbon fork were on a steel frame? Would the steel
frame fail similarly? Either way, I don't know.

I believe the steel frame WOULD fail similarly. Personal experience
suggests so:
http://home.comcast.net/~lines_tim/poor_schwinn.JPG

Tim Lines said:

Phil said:

Nick Payne wrote:

Quoted message said:

Quoted message said:

One might say, however, that the carbon frame is weaker than a steel frame.
What would happen if the carbon fork were on a steel frame? Would the steel
frame fail similarly? Either way, I don't know.

I believe the steel frame WOULD fail similarly. Personal experience
suggests so:
http://home.comcast.net/~lines_tim/poor_schwinn.JPG

On the contrary, your photo shows precisely not that: bending but not
breaking apart. That's what you want in a bicycle frame failure, not
what happened with the carbon fiber reinforced resin frame.

Matt O'Toole said:

Mostly true, but the lightest metal frames would break too -- or bend to
the point of complete collapse, with the same result.

The problem is not the material, but shaving weight to the point where
there's no margin for error.

Similar but not quite... many years ago I was riding a Klein in a crit
and a rider ahead of me clipped a plastic cone which marked the course.
It lazily spun around and ended up getting stuck between my front wheel
and frame. I did a quick headplant, and the bike soared into the air
(20-30ft according to witnesses)... but the bike, the fork, and the
front wheel were all straight and true. Of course having the cone stuck
in there would have kept the fork from bending back.

Still think that Klein was amazingly tough... since it experienced at
least a dozen hard crashes without structural damage... and weighed
only 3.5lbs with bottom bracket.

41 said:

Tim Lines said:

Phil said:

Nick Payne wrote:

Quoted message said:

Quoted message said:

One might say, however, that the carbon frame is weaker than a steel frame.
What would happen if the carbon fork were on a steel frame? Would the steel
frame fail similarly? Either way, I don't know.

I believe the steel frame WOULD fail similarly. Personal experience
suggests so:
http://home.comcast.net/~lines_tim/poor_schwinn.JPG

On the contrary, your photo shows precisely not that: bending but not
breaking apart. That's what you want in a bicycle frame failure, not
what happened with the carbon fiber reinforced resin frame.

Well in that case I am pretty sure that the owner of that Schwinn made
a comparable crash ^^

But indeed, CF breakage is scary. I have seen CF go in ways I never
have seen with Steel and Alu. I'm prepared to believe CF has the same
risk of failure as Steel and Alu, but when it goes... it tends to go
all the way.

41 said:

bending but not breaking apart. That's what
you want in a bicycle frame failure,

Why?

JT

****************************
Remove "remove" to reply
Visit http://www.jt10000.com
****************************