Snapped bars

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horizon
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Re: Snapped bars

Postby horizon » 13 Mar 2017, 11:27am

So It was caused by either/or/all of:

1. Use of an inadequate material (aluminium) for the bars
2. Extreme (or top end) use in terms of mileage
3. Top end use in terms of configuration (bar ends etc)
4. Top end use in terms of pulling, braking, steering etc
5. General fatigue limit exceeded over time, not usage
6. Cracks created by sharp stem edges
7. Use of too thin a gauge of aluminum
8. Failure to test for potential cracks
9. Bars made from sub-standard/cheap aluminium
10. Failure of tests to identify potential cracks
11. Lack of strengthening or safety device in the bars
12. Fauit in the manufacturing process
13. Lack of post production quality checking
14. Failure by OP (and the rest of us) to make routine change of bars
15. Lack of indicated life of bars in purchase documentation and safety warning
16. Combination of age of bars (fatigue over time) and heavy usage
17. Over-tightening of stem bolts
18. Completely unlucky, rare, unexpected, remote chance, one-off event
19. And Brucey's point about incorrect design (centre (typically 1" dia) part is formed by upsetting a 7/8" dia tube)

I can think that only point #14 is an adequate response (i.e. change bars regularly) from a personal point of view. Are we otherwise all at sea on this?
Last edited by horizon on 13 Mar 2017, 12:16pm, edited 1 time in total.
When the pestilence strikes from the East, go far and breathe the cold air deeply. Ignore the sage, stay not indoors. Ho Ri Zon 12th Century Chinese philosopher

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meic
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Re: Snapped bars

Postby meic » 13 Mar 2017, 11:43am

Rose say in the handlebar section of their catalogue.

ATTENTION
Replace aluminium stems and handlebars at least every two years or 10,000km.
All safety-relevant components should be replaced immediately after a fall!


Quite a bit of other safety stuff like not mixing sizes or using aluminium bars with steel stems.

That is their posterior well and truly covered then.
Yma o Hyd

Bowedw
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Re: Snapped bars

Postby Bowedw » 13 Mar 2017, 11:52am

Probably wrong but I think the centre section on kalloy bars have an external, sleeve to increase the diameter at the stem. The sort of bars fitted to Dawes Raleigh etc in the 1990's. I found they always creaked and used to change them for quality bars in 7075. Come to think of it, these bars are now 20 years plus old. Now wondering should I renew??
Last edited by Bowedw on 13 Mar 2017, 2:00pm, edited 1 time in total.

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horizon
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Re: Snapped bars

Postby horizon » 13 Mar 2017, 1:19pm

meic wrote:Rose say in the handlebar section of their catalogue.

ATTENTION
Replace aluminium stems and handlebars at least every two years or 10,000km.
All safety-relevant components should be replaced immediately after a fall!


Quite a bit of other safety stuff like not mixing sizes or using aluminium bars with steel stems.

That is their posterior well and truly covered then.


As that stands, it's a game changer. Very few people are buying bikes and bars on that basis - it's almost unthinkable. It may also mean that Rose are saying that their products are unfit for purpose. However, even worse, by trivialising an important issue, Rose are simply encouraging people to ignore it and carry on.
When the pestilence strikes from the East, go far and breathe the cold air deeply. Ignore the sage, stay not indoors. Ho Ri Zon 12th Century Chinese philosopher

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foxyrider
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Re: Snapped bars

Postby foxyrider » 13 Mar 2017, 5:02pm

horizon wrote:
meic wrote:Rose say in the handlebar section of their catalogue.

ATTENTION
Replace aluminium stems and handlebars at least every two years or 10,000km.
All safety-relevant components should be replaced immediately after a fall!


Quite a bit of other safety stuff like not mixing sizes or using aluminium bars with steel stems.

That is their posterior well and truly covered then.


As that stands, it's a game changer. Very few people are buying bikes and bars on that basis - it's almost unthinkable. It may also mean that Rose are saying that their products are unfit for purpose. However, even worse, by trivialising an important issue, Rose are simply encouraging people to ignore it and carry on.


Not sure how that's trivialising the issue.

Sounds like reasonable advice, more interested in why the those particular time/distance figures are proposed. 2 years of daily riding German cobbles would kill anything, 10k km would be a lifetimes riding for some, a year for others.

Bear in mind that a large proportion of Rose customers are not dyed in the wool cycling beardies but ordinary man/woman in the street.

I've never suffered broken bars, bent a couple of pairs in falls which were replaced. My sleeved 64's date from the mid seventies and when re fitted last were free from external signs of fatigue. I'm probably more concerned about my Zipp carbons - now all of two years old!

IME wider stem clamp contact areas reduce the liklihood of breakage.
Convention? what's that then?
Airnimal Chameleon touring, Orbit Pro hack, Orbit Photon audax, Focus Mares AX tour, Peugeot Carbon sportive, Owen Blower vintage race - all running Tulio's finest!

cycle tramp
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Re: Snapped bars

Postby cycle tramp » 13 Mar 2017, 9:21pm

RJS wrote:Cycle tramp, as I expect you know steel bars aren't unsnapable, I had a friend who's (straight steel bars) broke braking down hill, admittedly they were probably quite old, had a broken collar bone as well :(
Cheers, Rob.


Y'know given the right set of circumstances I don't know of anything at can't be broken. It would have been interesting to see the bars... I would have suspected some internal corrosion perhaps, but then again, if he was a big strong guy then perhaps give the right situation...

Of course, such risks are compounded by speed and for that reason alone I'm loathed to ride at any speed faster than 12 mph... ;-)

RJS
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Re: Snapped bars

Postby RJS » 13 Mar 2017, 9:31pm

You're right of course cycle tramp, a fairly heavy chap, breaking for a roundabout at the bottom of a very steep hill, and I suspect the bars were old and consequently corroded internally.
Cheers, Rob.

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CREPELLO
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Re: Snapped bars

Postby CREPELLO » 13 Mar 2017, 11:43pm

I remember my straight bars snapping on a Carlton Conti that I'd rebuilt when I was about 13. It was quite a shock riding into school one morning (a year or so later) when the RH bar suddenly gave way (fortunately there no other kids around to see my shock!). IIRC, the centre section was internally reinforced. I seem to recall seeing rust around the internal sleeve (it was an alu bar) - could that be right?

Anyway, my most recent build (Dawes Audax - rebuild) has a straight bar which with an external, loose, sleeve (shim). I wonder which is best? I suspect the old school bars had a rough edged internal sleeve which gave rise to the crack - though I'm not at all sure how an internal sleeve is inserted?? I feel happier somehow with the external sleeve.

PH
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Re: Snapped bars

Postby PH » 14 Mar 2017, 10:39am

CREPELLO wrote:I'm not at all sure how an internal sleeve is inserted?? I feel happier somehow with the external sleeve.

I have no idea how bars are manufactured, none of mine seem to have any sleeve, none that I've been looking at as replacements have a viable one and none mention sleeves in the description. I wonder if this is what Brucey meant by:
if they are the kind of bars that I am thinking of, where the centre ( typically 1" dia) part is formed by upsetting a 7/8" dia tube

If that's the case I also wonder if oversize bars are a bad idea, as the transition from grip to clamp is greater.

PH
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Re: Snapped bars

Postby PH » 14 Mar 2017, 6:00pm

Well, got round to removing the bars from the bike. I was wrong about the make, they're M-wave rather than Kalloy.
A little shocked at the state of them, there's a few marks that look like they could develop cracks and a fair bit of corrosion under the Rohloff shifter, as well as pretty scored by the Handlebar bracket. Maybe an accident waiting to happen.
Moving on, new kit ordered, Nitto bars and Zenith stem.
ImageP1000331 by Paul, on Flickr

rualexander
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Re: Snapped bars

Postby rualexander » 14 Mar 2017, 9:05pm

It seems that there should be some kind of rubbery/plasticy structural foam or something that should be injected into handlebars that would result in bars slowly bending when the alloy fails, given the consequences of rapid bar snapping.
Does such a material exist?

RJS
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Re: Snapped bars

Postby RJS » 14 Mar 2017, 10:04pm

I've heard of people injecting silicone, (bath sealer etc.), in one end of 'bars and out of the other, but that was to dampen vibration. It would add to the weight somewhat as well.
Cheers, Rob.

MikeDee
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Re: Snapped bars

Postby MikeDee » 2 Apr 2017, 7:34pm

PH wrote:Well, got round to removing the bars from the bike. I was wrong about the make, they're M-wave rather than Kalloy.
A little shocked at the state of them, there's a few marks that look like they could develop cracks and a fair bit of corrosion under the Rohloff shifter, as well as pretty scored by the Handlebar bracket. Maybe an accident waiting to happen.
Moving on, new kit ordered, Nitto bars and Zenith stem.
ImageP1000331 by Paul, on Flickr


Good move changing the stem too, as it may have contributed to the failure since it occurred at the edge of the stem clamp.

aljohn
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Re: Snapped bars

Postby aljohn » 2 Apr 2017, 8:47pm

About 1960 I bought a Carlton Flyer track frame - new. It was a steel frame , so chuffed was I that I bought - new - Cinelli steel track bars and stem. After a years use I decided that I'd been a little ambitious in my (personal) bike fit and thought the handlebars could be raised a little for comfort - most of my riding was on the road. As I pulled the stem up there was a semi circular crack around the stem, fractionally below the lock nut, and invisible until then. The crack was rusty, so I assume that rain water had sat in that tiny space and slowly rusted my stem. I think I was lucky to have found it, but surprised that the crack just went half way around the stem. When I think of the force when hauling on the bars in a sprint then I was lucky that there was still some steel supporting me. I didn't buy a Cinelli stem to replace it.... mind you I possibly bought an alloy one, which perhaps wasn't the cleverest idea with steel bars...?

mercalia
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Re: Snapped bars

Postby mercalia » 2 Apr 2017, 9:04pm

so the morale is dont put too much strain on alloy bars? then they wont break?