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Sickening Sound when tightening stem on Easton Carbon Bars(12 posts)

Sickening Sound when tightening stem on Easton Carbon Barscdlynx
Apr 3, 2002 8:45 AM
During my weekly tightening ceremony, I heard one of the sounds you don't ever want to hear carbon make, kind of a cracking crunching sound. I have a Thomson stem (with four tightening bolts) and the Easton EC-90 bars. I gently snugged each bolt using a cross 4 pattern and then I heard what sounded to me like a cracking sound. I see no damage on either side of the stem and can feel no flex in the bars and there is no other stress (cracking)noise when I put pressure on the bars. Now the question: I'm afraid to loosen the stem and find a mess of carbon fibers under the stem plate. Has anyone had this experience, and is there a risk of stress failure down the road with these bars? Thanks, cdL
"Weekly tightening ceremonies"TJeanloz
Apr 3, 2002 9:04 AM
Interestingly, Deda did a survey of mechanics last year and found that most were torquing their stems far beyond the requirements, and into dangerous territory. Bolts shouldn't be tightened by ritual- only when they need to be. And a small torque wrench is the only way to really know.
"Weekly tightening ceremonies"cdlynx
Apr 3, 2002 9:43 AM
Just a little clarification: I don't actually check and tighten my stem weekly (perhaps should have been weakly), but just happened to be the pre-ride check this time. Did not use a torque wrench, but just snugged a little 'looseness out'!
Is it really worth it?ColnagoFE
Apr 3, 2002 9:53 AM
With all that fiddling do you really notice so much of a diff in weight reduction that a 260 gram stem wouldn't do the trick just as well--without all that fiddling around with torque wrenches? I looked at one of those easton bars the other weekend. Not much there and light as a feather. I'm sure they did the R&D to make sure they are strong enough but after holding one I'd never bolt one onto my bike and trust it in a out of the saddle sprint.
Retorquing,TJeanloz
Apr 3, 2002 10:56 AM
Most mechanics who habitually re-torque things learned this habit long before handlebars and stems were stupid light.

I have an Easton bar, and I sleep o.k. at night, dreaming of sprint finishes.
Not really about weight advantage..........cdlynx
Apr 3, 2002 11:04 AM
I installed this bar late last summer for the vibration (or lack there-of) adavantage...I have diabetes, and my hands go numb very easily despite many different glove and bar wrap experiments. This bar is very comfortable, and readily available on the ( 5th letter)-bay site for under $90 new if you really shop. If necessary, I would buy another for the comfort factor alone. I will take post suggestions seriously though, and check to see the status under the plate to save my teeth, nose, collar bone, etc. thanks
"Weekly tightening ceremonies"grzy
Apr 3, 2002 6:08 PM
Just "snugging a little looseness out" means different things to different people. Recently pick up a used frame and the previous owner had over tightened the water bottle screws to the point of partially stripped. And then there is my wife of good solid stock....

Get thee a torque wrench and stop guessing.

BTW - the crunching noise wasw the sound to fibers coming loose from the epoxy matrix and some failing. Still, I don't think you have too much to worry about - there's a "factor of safety" built into the design. You'll probably be fine with normal use, but something very unusual or a wreck and you may see a premature failure. The Easton bars are pretty solid - my MTB gets tossed down trails and ghost riden all the time.
I'd rather find a pile of loose carbon fiber than loose teeth...IAmtnbikr
Apr 3, 2002 9:54 AM
pull it and check it! Carbon fiber will have a catastrophic failure with no warning! The sound was a clue for you to check, before you test your medical insurance.
a thought...g-money
Apr 3, 2002 11:24 AM
Are you SURE it was the carbon fiber? Usually, if you crack CF you know it. Plus it's rather unlikly unless the bar had a problem in the first place OR you mega over-torqued your stem. My quess is you need to regrease your stem bolts. It sounds as though you heard the tell-tale creak of a steel screw in an aluminum hole that is under-lubed. It can sound very disturbing and it's the precursor to striping, and or siezure of the bolt in the hole... Take out your bolts and regrease (I use anti-sieze, it seems to last longer and won't allow your bolt to sieze into the aluminum)... Then you'll know if you chanked your bar... (prolly not)

Just a thought...
re: Sickening Sound when tightening stem on Easton Carbon BarsJimP
Apr 3, 2002 12:15 PM
I had a conversation with an Easton tech last year about indications of potential failures with carbon bars and seatposts. His response was that you would see white stress risers ( little light colored lines parallel to the bar or stem ) before you should be worried. You might look closely at the bar where it meets the stem for these indications.
Easton bar failure...pulled from velonews forum.PsyDad
Apr 3, 2002 1:52 PM
Did your noise sound like velcro ripping? Check out this reply from velonews.

Date: 04-03-02 16:24

I have the Easton bars. I really like them, but I've only used 2 other bars, both of them being cheap AL and possibly too small. I never had a problem with flex or road buzz with them. I am also a novice rider, so take that into account.

That said, I feel I should add my experience to the above statement. Last year, mid-season, I had some problems with my handlebars rotating up and down. After talking to people, I found a fix for the issue and tightened them a little and put locktite on the bolts. Problem fixed. I then had problems later in the season. Apparantly the bolts were coming loose. So I retightened them. *Pause for collective groan, gasp, and other noises of general pain* It would seem my stem bolts really preferred to be out of the stem rather than in it.

Right about this point, it would be smart to say one thing : Buy a torque wrench. At my next race, I was happily riding along (a crit on bad pavement), and I heard a "nice" sound that one can never forget. It was the sound of velcro ripping. You might think "Why would Velcro be ripping on his bike?". I quickly discovered that carbon and velco sound very similar. Yes, my bars broke. But it was not just a small break : they broke completely in two pieces.

Now for the good part : Easton replaced them for free. I'm not saying they will always do this, but they felt that they should, since the break was so intense. The stem I was using is a TTT Forgie. I have since switched to the Easton EM90 stem, as they recommend it. Other than the breaking, the bars were great. I feel that carbon bars would have broke under those conditions regardless of the maker. Everyone else I know that has tried the bars loves them (about 5 people). The flat sections on the bars are wonderful.

Hope it helps,
Nick
I've heard that terrible sound before....parkmeister
Apr 8, 2002 11:03 PM
...when trying to cut a carbon fiber steerer tube down to size. The installation instructions that came with the fork warned not to use a hacksaw to cut the steerer; only a cutter made specifically for cf should be used. Well I didn't have that cutter so I stupidly improvised using a pipe cutter. While the pipe cutter cut through the outer layers of the steerer, it acted like a vise and squeezed the tube to the point where the inside of the tube was overstressed causing the carbon fiber to split and crack. I think your overtightened stem stressed and cracked your cf bars in a similar fashion.

For safety's sake, I would definitely check your bars thoroughly before using them. Even the slightest amount of damage could render the bars unsafe.

Good luck,

Gary