|Sickening Sound when tightening stem on Easton Carbon Bars||cdlynx|
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.|
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.|
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 Bars||JimP|
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,
|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.