Handlebar Failure

asqui said:

The last club ride I went on was about three months ago. I was worried about wether I'd be on form
to keep up but fortunately I did alright. That is, until on our way back *this* happened:

btinternet.comBarsOpen ↗

The worst part (given that I didn't fall off or get run over) is that I spent £7 and an hour or
two changing the bar tape... *yesterday*

The handlebar tubing sheared off as I went over the bumpy side-line on a main road. I moved back
to the right of it, then through the next couple of seconds had the following train of thought:
"Why am I swerving into the middle of the road?" "Why is my bike handling weirdly?" "Hmmm, my
left hand feels awfully low." "...and the end of my handlebar about to touch my rim." "This can't
be good."

Fortunately it came apart gently, and not completely -- I can't imagine the spectacular crash that
would have taken place if my left hand instantly lost all support (especially if I was sprinting
or something). As I slowed I transferred my left hand to the stem, and tried to brake and
negotiate said bumpy lane marking without crashing (I suck when it comes to one-handed
braking/maneuvering).

My colleagues suggested that it was probably scratched (maybe when being put into the stem --
which I understand can be a fairly forceful procedure with that style of stem) and I think I can
make out a scratch at the top of the tubing where it presumably started shearing off. They also
recommended I go for an open-ended racing-style stem, which is gentler on the bars.

I've had the bike since June and have done just over 2700mi on it. I've dropped it a couple of
times on each side and had one proper crash (the bike came down on the right side though, so that
couldn't have been influential).

Do you think they'll do it as a warranty replacement?

If not, should I change to an open-ended stem?

Alloy bars need to be replaced periodically - 3TTT give recommendations based on mileage and/or
age, whichever comes sooner. However, 2700 miles is well within even the recommendations for
professional racing.

Onto the failure: firstly, longitudinal scratches caused when sliding the bars in wouldn't have
caused this failure. However, when fitting new bars it's a good idea to chamfer the edges of the
clamp on the stem with a file, as sharp edges at the bar/stem interface can notch the bar during
normal riding and lead to this kind of failure. This hasn't been done on your stem.

I also use grease between the bars and the stem, but this is mainly to prevent any creaking.

BTW, what make and model of bars and stem are they?

It's worth trying for a warranty replacement, but don't expect anything if you mention you've
dropped the bike. I doubt this has anything to do with the failure - I think they're just overlight
and substandard bars - but a bad shop will use any excuse.

Zog The Undeniable said:

asqui said:

The last club ride I went on was about three months ago. I was worried about wether I'd be on
form to keep up but fortunately I did alright. That is, until on our way back *this* happened:

Just another thought - when adjusting the bars, it's possible that the mechanic twisted the bars
repeatedly, without prising open the stem first. This would have had a similar effect to a plumber's
tube cutter.

On Sun, 25 Jan 2004 18:05:21 +0000, Zog The Undeniable <[email hidden]>

Quoted message said:

asqui said:

btinternet.comBarsOpen ↗

...when fitting new bars it's a good idea to chamfer the edges of the clamp on the stem with a
file, as sharp edges at the bar/stem interface can notch the bar during normal riding and lead to
this kind of failure. This hasn't been done on your stem.

I'm not sure; I think I can see a fairly smooth radius on this stem edge. This looks like a 3TTT
stem, and 3TTTs I've seen have had a radius, presumably to reduce the effects on the bar's
fatigue life.

"Zog The Undeniable" <[email hidden]> wrote in message
"]news:[email hidden]...

Quoted message said:

Zog The Undeniable wrote: Just another thought - when adjusting the bars, it's possible that the
mechanic twisted the bars repeatedly, without prising open the stem first. This would have had a
similar effect to a plumber's tube cutter.

Yeah, you can kinda see scratches around the circumference near the stem, conincidentally, right
where it broke. I'm surprised it broke so soon though. 2700 miles doesn't seem like that much even
with scratches like that. But I've rarely seen broken handlebars so I can't really say wity any
authority. I think you'll definitely get a warranty job on that if you scream enough. I suspect, if
you're a shop regular, they'll give you a discount on a better set of bars, maybe cost.

Cheers,

Scott..

you've covered it, and personally, i'd say twisting is likely although the camera angles emphasize
the region where the bar has torn, not fatigued - the top where the stem and bar interface appears
to be exactly where there is a smother fatigue crack surface and where such scarring would have
occurred if twisted.

to avoid in the future,

1. make sure the stem clamp is sufficiently open to allow the bar to be inserted without any
twisting & therefore scarring of the bar. /any/ scratch can be a fatigue nucleation point.

2. pay that little extra for a quality bar. ones that have been shot-peened are available. this
creates good fatigue resistance characteristics.

apart from regular changes of bars, using only quality components and god fitting practice, it may
be worth considering alternatives: i'm personally uncommitted at this stage, but if this failure
really worries anyone, and i know it did me when i had one, it may be worth considering a carbon
bar. i am not using a carbon road bar at this point, but a well made carbon bar does have superior
fatigue characteristics to aluminum. i use a carbon mountain bar and having gotten over my initial
random breakage worries, far feel more secure with this bar now than the aluminum bar i was using
previously.

also, the old cinelli bars with the 26.6mm clamp were excellent. they had an external shim at the
mounting point. this is excellent design because any defects or damage at the shim cannot
immediately propagate into cracks of the bar itself. a good condition, low mileage bar of that style
is something in which you can have a lot of confidence, albeit not of the anatomical style.

jb

Zog The Undeniable said:

Zog The Undeniable said:

asqui said:

The last club ride I went on was about three months ago. I was worried about wether I'd be on
form to keep up but fortunately I did alright. That is, until on our way back *this* happened:

Just another thought - when adjusting the bars, it's possible that the mechanic twisted the bars
repeatedly, without prising open the stem first. This would have had a similar effect to a
plumber's tube cutter.

A couple of things-

#1: Always concerned about mysterious failures when there had previously
been a crash. In the prior crash, was the handlebar tape damaged *at all*? You can do a fair amount
of damage to a bar without that much outward evidence.

#2: Looks like a 3TTT stem, but can't tell about the bar. 3TTT stems run a
bit on the small side (25.8mm I think) and if you were using a bar that was slightly out of
tolerance (on the large side) of the conventional 26.0mm diameter, that could be a
contributing factor.

#3: If you're using a 240 (or less)- gram bar, first question is why,
second point is that they're much more susceptible to problems in an imperfect world.

Glad you weren't hurt badly! I've had two nasty stem failures; they're not fun either. I have no
idea how I stayed upright for the second one, which failed during an uphill sprint.

--Mike-- Chain Reaction Bicycles chainreactionbicycles.comchainreactionbicycles.comOpen ↗

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

Quoted message said:

The last club ride I went on was about three months ago. I was worried

about

Quoted message said:

wether I'd be on form to keep up but fortunately I did alright. That is, until on our way back
*this* happened:

btinternet.comBarsOpen ↗

The worst part (given that I didn't fall off or get run over) is that I spent £7 and an hour or
two changing the bar tape... *yesterday*

The handlebar tubing sheared off as I went over the bumpy side-line on a main road. I moved back
to the right of it, then through the next couple

of

Quoted message said:

seconds had the following train of thought: "Why am I swerving into the middle of the road?" "Why
is my bike handling weirdly?" "Hmmm, my left hand feels awfully low." "...and the end of my
handlebar about to touch my rim." "This can't be good."

Fortunately it came apart gently, and not completely -- I can't imagine

the

Quoted message said:

spectacular crash that would have taken place if my left hand instantly

lost

Quoted message said:

all support (especially if I was sprinting or something). As I slowed I transferred my left hand
to the stem, and tried to brake and negotiate

said

Quoted message said:

bumpy lane marking without crashing (I suck when it comes to one-handed braking/maneuvering).

My colleagues suggested that it was probably scratched (maybe when being

put

Quoted message said:

into the stem -- which I understand can be a fairly forceful procedure

with

Quoted message said:

that style of stem) and I think I can make out a scratch at the top of the tubing where it
presumably started shearing off. They also recommended I

go

Quoted message said:

for an open-ended racing-style stem, which is gentler on the bars.

I've had the bike since June and have done just over 2700mi on it. I've dropped it a couple of
times on each side and had one proper crash (the

bike

Quoted message said:

came down on the right side though, so that couldn't have been

influential).

Quoted message said:

Do you think they'll do it as a warranty replacement?

If not, should I change to an open-ended stem?

Thanks in advance, Dani

asqui said:

btinternet.comBarsOpen ↗ Fortunately it came apart gently, and not completely --
I can't imagine the spectacular crash that would have taken place if my left hand instantly lost
all support

Not necessarily. I broke an old set of handlebars about two years ago while cornering, and while
fortunately the side outside the corner came off, it came off basically instantaneously. Although I
veered wildly, I didn't pancake; I stopped, stuffed the loose chunk into the other brake cable loop
by the stem, and limped down to the nearest station clutching the stem with my left hand.

[Where I waited 2 hours in freezing weather for a train which is nominally half-hourly - if I'd
known, I could have walked home - but that's a side issue.]

Those bars were ten years old and cracked my ribs in a crash 2 years before _that_, which may well
explain their failure. Irritatingly, the Nitto Noodle bars I now use are not available in steel.
--
David Damerell <[email hidden]> flcl?

David Damerell said:

Not necessarily. I broke an old set of handlebars about two years ago while cornering,

I am still confidently using the original stems&handlebars on thirty year old bikes. Those Cinelli
and 3ttt items were really well built. Provided they had not crashed, nor were improperly dis- and
re-assembled, they were made to last.

Sergio Pisa

P.s. Knock on wood!

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

David Damerell said:

Not necessarily. I broke an old set of handlebars about two years ago while cornering,

I am still confidently using the original stems&handlebars on thirty year old bikes. Those Cinelli
and 3ttt items were really well built. Provided they had not crashed, nor were improperly dis- and
re-assembled, they were made to last.

More important than age is how many miles are on the bars and how big is the user. Some folks have
so many bikes that each bike they own gets very few miles on it, so age is not a good indicator.
-------------
Alex

Sergio SERVADIO said:

David Damerell said:

Not necessarily. I broke an old set of handlebars about two years ago while cornering,

I am still confidently using the original stems&handlebars on thirty year old bikes.

Er - you may have noticed how the set I broke had cracked my ribs earlier in their life.
--
David Damerell <[email hidden]> flcl?

Alex Rodriguez said:

More important than age is how many miles are on the bars and how big is the user. Some folks have
so many bikes that each bike they own gets very few miles on it, so age is not a good indicator.

Alex, I am totally with you on this one. But, I must add that those two bikes I am referring to have
so many chilometers on them, mostly on rough course and sometimes on rough terrain too. How many,
nobody can tell. Nor am I lightweight; with them both I have taken many bike trips over the Alps
carrying a good backpack.

Any time you are around, I'd be proud to show you.

Sergio Pisa

"Mike Jacoubowsky" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

A couple of things-

#1: Always concerned about mysterious failures when there had previously
been a crash. In the prior crash, was the handlebar tape damaged *at all*? You can do a fair
amount of damage to a bar without that much outward evidence.

Yes, I have had one crash. Chain came off while sprinting at speed, crotch made contact with
crossbar. I might have recovered at this point but lost control and came down on my right knee. Four
stitches. The bike landed on the right side on the pedal, big chainring (don't know how that
happened -- both wheels were intact. Maybe the crown of the road?), and the handlebar/shifter got a
bit of a scrape (in fact, that was the reason for changing the tape). Shifter was slightly out of
line and I had to twist it back. The bar got a small bit of road contact just below the right
shifter, less than 0.5cm of minor scratching.

Note that this was on the right hand side.

More recently I was being an idiot and dropped it on the left side on a hard outdoor surface. Impact
was on the end of the bar and shifter, with slight scrapage on both.

Quoted message said:

[...]
#3: If you're using a 240 (or less)- gram bar, first question is why,
second point is that they're much more susceptible to problems in an imperfect world.

Bars were Modolo T-Poc. Website says 280gm.
(geoplan.it1 road handlebars temp.phpOpen ↗)

Quoted message said:

Glad you weren't hurt badly! I've had two nasty stem failures; they're not fun either. I have no
idea how I stayed upright for the second one, which failed during an uphill sprint.

Stem failure? Ouch. I'm getting images of jagged stem remains meeting a sweaty chest... I'm glad you
managed to control it.

Dani

Zog The Undeniable <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Onto the failure: firstly, longitudinal scratches caused when sliding the bars in wouldn't have
caused this failure. However, when fitting new bars it's a good idea to chamfer the edges of the
clamp on the stem with a file, as sharp edges at the bar/stem interface can notch the bar during
normal riding and lead to this kind of failure. This hasn't been done on your stem.

The stem is 3TTT, but has no other markings indicating model. It's hard to see if the edges have
been chamfered but I'll have a closer look later, and bring it up when visiting the LBS tomorrow.

Quoted message said:

I also use grease between the bars and the stem, but this is mainly to prevent any creaking.

Now that you mention creaking, I had a bit of that when I first got it. I mentioned it at the 6-week
service and they tightened up the stem and it went away (for the most part -- can still hear slight
crackling when *really* putting pressure on). This might have been a contributing factor... as Mike
Jacoubowsky said:

~ 3TTT stems run a ~ bit on the small side (25.8mm I think) and if you were using a bar that was ~
slightly out of tolerance (on the large side) of the conventional
26.0mm ~ diameter, that could be a contributing factor.

Quoted message said:

BTW, what make and model of bars and stem are they?

3TTT stem. No idea of model. The bars are (were?) Modolo T-Poc (Other markings: "5086 H32 Alloy"😉:
geoplan.it1 road handlebars temp.phpOpen ↗

(Offtopic: geoplan.itath image.phpOpen ↗ What would the warning label
on these carbon bars be warning against, just out of interest?)

Dani

"S. Anderson" <[email hidden]> wrote in message
news:<[email hidden]>... [...]

Quoted message said:

I think you'll definitely get a warranty job on that if you scream enough. I suspect, if you're a
shop regular, they'll give you a discount on a better set of bars, maybe cost.

I don't think they actually stock these exact bars (the bike is a Dawes Horizon), so I don't know
what they would replace them with. What would be your recommendations for replacement? Is there any
point in changing to a open-ended race-style stem? (Is it even feasible with that headset?)

Dani

Digging up a post on handlebar failure from 2002:

groups.google.comgroupsOpen ↗
8&safe=off&selm=s4Iw8.2684%24bu.1429%40nwrddc03.gnilink.net

Jay said:

Any irregularity on the surface of a component can accelerate fatigue failure [...] Whether you
should be worried would really depend on an analysis or failure test of the component, both of
which are way more expensive than new bars.

It didn't occur to me sooner that testing/analysis was a possibility, but as it happens a couple of
cycling enthusiasts from my university are studying Mechanical Engineering. Apparently one of them
showed the photos to a lecturer who became quite interested in having a look at the failure and
running some tests to find out what happened!

On another note, "rick fetters" posted my photos to sci.engr.metallurgy, which (so far) has resulted
in a matter-of-fact reply talking about "Stress concentration due to severe cross sectional change":

groups.google.comgroupsOpen ↗
8&safe=off&th=990bf7fd3bf2d2da&seekm=40150890.D4414E4F%40billboeing.com.remove.the.bill&frame=off

Unfortunately I don't understand what all this "cross sectional change", "gooseneck", and "darts"
terminology means...

asqui

"Mike Jacoubowsky" <[email hidden]> wrote in message
news:<[email hidden]>... [...]

Quoted message said:

#2: Looks like a 3TTT stem, but can't tell about the bar. 3TTT stems run a
bit on the small side (25.8mm I think) and if you were using a bar that was slightly out of
tolerance (on the large side) of the conventional 26.0mm diameter, that could be a
contributing factor.

[...]

I just made some measurements with Vernier Calipers.

Bars came in at precisely 26.0mm. I managed to get some diametrically opposed contact on the inside
diameter of the stem clamp in it's current, untouched, position (failed tubing still clamped) and
measured between 25.5 and 25.7mm on several trials.

Since my original post I have remembered that at the free 6 week adjustment service I mentioned
creaking coming from the stem clamp. They explicitly reported that they had tightened it up (No
mention, or signs, of grease were present) and the creaking all but dissappeared (was still minorly
present under much strain).

I don't believe I have ever touched that bolt myself, but I am guessing it was tight to start with
and then became *very* tight after the service. Presumably when the other half is unclamped and
removed it will become apparent if the bar was deformed by excess pressure from the clamp.

The edge of the clamp appears to have a small radius on it. I don't know how big a radius people
are talking about when they speak of smoothing the clamp edges -- it does not feel sharp to the
touch, but is barely detectable by eye (possibly to do with the fact that the bar remains are
still clamped).

Thanks to everyone for your advice so far.

Dani / asqui

asqui said:

(Offtopic: geoplan.itath image.phpOpen ↗ What would the warning
label on these carbon bars be warning against, just out of interest?)

"If you've ever broken a set of handlebars, you'd have to be verrueckt to use carbon bars."

--

David L. Johnson

__o | "What am I on? I'm on my bike, six hours a day, busting my ass. _`\(,_ | What are you on?"
--Lance Armstrong (_)/ (_) |

Quoted message said:

I just made some measurements with Vernier Calipers.

Bars came in at precisely 26.0mm. I managed to get some diametrically opposed contact on the
inside diameter of the stem clamp in it's current, untouched, position (failed tubing still
clamped) and measured between 25.5 and 25.7mm on several trials.

Not enough to be a problem...

Quoted message said:

Since my original post I have remembered that at the free 6 week adjustment service I mentioned
creaking coming from the stem clamp. They explicitly reported that they had tightened it up (No
mention, or signs, of grease were present) and the creaking all but dissappeared (was still
minorly present under much strain).

...except that it's possible your bars were overtightened in order to get rid of the squeaking.
Perhaps *way* overtightened, which could lead to a weakened state that would encourage further
damage in a fall. The slight mis-match of a 25.8 stem vs 26.0 bar could have been partly responsible
for the noise.

Quoted message said:

I don't believe I have ever touched that bolt myself, but I am guessing it was tight to start with
and then became *very* tight after the service. Presumably when the other half is unclamped and
removed it will become apparent if the bar was deformed by excess pressure from the clamp.

Maybe, but could be tough to say for sure. If you see significant indentation on that side, it would
give someone reason to wonder!

Quoted message said:

The edge of the clamp appears to have a small radius on it. I don't know how big a radius people
are talking about when they speak of smoothing the clamp edges -- it does not feel sharp to the
touch, but is barely detectable by eye (possibly to do with the fact that the bar remains are
still clamped).

--Mike-- Chain Reaction Bicycles chainreactionbicycles.comchainreactionbicycles.comOpen ↗

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

Quoted message said:

"Mike Jacoubowsky" <[email hidden]> wrote in message

news:<[email hidden]>...

Quoted message said:

[...]

Quoted message said:

#2: Looks like a 3TTT stem, but can't tell about the bar. 3TTT stems

run a

Quoted message said:

Quoted message said:

bit on the small side (25.8mm I think) and if you were using a bar that

was

Quoted message said:

Quoted message said:

slightly out of tolerance (on the large side) of the conventional 26.0mm diameter, that could be
a contributing factor.

[...]

I just made some measurements with Vernier Calipers.

Bars came in at precisely 26.0mm. I managed to get some diametrically opposed contact on the
inside diameter of the stem clamp in it's current, untouched, position (failed tubing still
clamped) and measured between 25.5 and 25.7mm on several trials.

Since my original post I have remembered that at the free 6 week adjustment service I mentioned
creaking coming from the stem clamp. They explicitly reported that they had tightened it up (No
mention, or signs, of grease were present) and the creaking all but dissappeared (was still
minorly present under much strain).

I don't believe I have ever touched that bolt myself, but I am guessing it was tight to start with
and then became *very* tight after the service. Presumably when the other half is unclamped and
removed it will become apparent if the bar was deformed by excess pressure from the clamp.

The edge of the clamp appears to have a small radius on it. I don't know how big a radius people
are talking about when they speak of smoothing the clamp edges -- it does not feel sharp to the
touch, but is barely detectable by eye (possibly to do with the fact that the bar remains are
still clamped).

Thanks to everyone for your advice so far.

Dani / asqui

Quoted message said:

On another note, "rick fetters" posted my photos to
sci.engr.metallurgy, which (so far) has resulted in a matter-of-fact
reply talking about "Stress concentration due to severe cross
sectional change":

I am a machinist and metalworker (and avid cyclist) and have posted to the metallurgy and materials
usenet groups when in need of technical/engineering experience. I was curious about the failure of
your handlebars, having experienced both a handlebar and frame failure in the past. I posted your
picture to sci.engr.metallurgy to get input from the engineering community. As "Asqui" mentioned
here is a link to the thread in the other group.

groups.google.comgroupsOpen ↗
8&threadm=bv487i%24e1u%241%40titan.btinternet.com&prev=/groups%3Fhl%3Den%26lr%3D%26ie%3DUTF-
8%26oe%3DUTF-8%26group%3Dsci.engr.metallurgy

I alsp recieved an insightful email from Bob in New Zealand.

From Bob Redfern in NZ.... The last handlebar, bike frame and microlight failures I had to
investigate were all the result of a common problem with high strength aluminium alloys - stress
corrosion cracking. The pictures provided are not adequate to show this and you need some
metallography. The sequence of events is that flexing caues cracking of the paint film then
chlorides (there are always enough chlorides available from sweat for example) and stress together
cause stress corrosion cracking. Its pretty insidious as the exceedingly small amount of corrosion
penetrates the tube walls and there is very little to observe right up to the failure time, even the
corrosion products are white and appear as very fine, faint hairlines on polished surfaces. The
manufacturers simply shrug there shoulders and suggest that the bars should be replaced frequently
(ie after their guarantee runs out). Anodising is not much help (and reduces the fatigue strength
anyway) as the flexing serves to crack the brittle film allowing access for the chlorides. However a
guy/gal whose bars break whilst going at high speed downhill is not a pretty sight.

If you can't find a friendly metallurgist then I will look at a small section cut from the vicinity
of the break for you. Ideally you require some fractography on the break as well. Email me for
additional information if you want.

Bob

Regards, Rick