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Old 02-14-10, 09:56 PM   #1
MrTuner1970
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Damaged Steerer?

What would you do if this was your steerer, knowing it was your life on the line?

Alpha Q carbon fork (GS-10). Flipped the stem and removed all the spacers. Tightening up the stem bolts, trying to be very careful not to over-tighten them (I don't yet have a torque wrench). Going fairly easy (so I thought) and hear not a crack, but more like a crick. Take stem and headset off to look, and see this: no crack, but there is a compression mark on the steerer tube. It looks as if it is only on the outer layer of carbon, as the attached pictures indicate.

Not having experience with this, my initial thought is that it's something that absolutely needs to be monitored, and possibly replaced just to be on the safe side. (I rode it around the neighborhood streets a few times, but haven't taken it out on a normal ride yet. The mark didn't change after the very short rides around the hood.) The compression mark looks to be 0.2 mm or so deep at most. I can afford a new fork, so that's not the issue. Would much rather replace it if there is any possibility of the steerer tube being significantly weakened by this over-tightening. Just imagining what results from a fork failure makes me ultra-queasy.

Replace or not? What say you all?
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Old 02-15-10, 03:14 PM   #2
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FWIW ... made contact with Alpha Q with the same email and pix. They recommended replacing the fork.

I don't know how much of that recommendation is legal CYA. But I'd rather be safe than broken up somewhere because of an accident. Ordered an Edge 2.0 fork today.

Dang, learning is expensive sometimes. But I'll never make this mistake again either. (Also ordering torque wrench today.)
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Old 02-15-10, 03:35 PM   #3
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yeah, you don't wanna mess with a damaged steerer. but yours isn't NEARLY as bad as the steerer-tube that I ran across last night. And that's taking into account that yours is carbon, vs. the one I saw last night being steel.
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Old 02-15-10, 03:39 PM   #4
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I cracked the steer tube on my Colnago Carbon Star for because I used the torque spec shown on the stem, it was the only spec I could find. The replacement cost me $800 including a discount.
A carbon fiber steer tube does not need more than 5 nm and less is probably good enough.

Al
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Old 02-15-10, 04:36 PM   #5
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I cracked the steer tube on my Colnago Carbon Star for because I used the torque spec shown on the stem, it was the only spec I could find. The replacement cost me $800 including a discount.
A carbon fiber steer tube does not need more than 5 nm and less is probably good enough.

Al
$800 ... Ouch!

The tech from Alpha Q said this: "Most stems including ours list a max torque spec on them. It lists the torque at which the hardware will be fatigued to the point of stripping or damage. Most specs are around 5-6Nm but most assemblies only need around half of that."

I'm thinking about maybe listing the damaged Alpha Q on eBay. Maybe some lightweight could use it. Heck, I really think it would be rideable, but at my current weight of 190 lbs., I don't want to be worrying about it on every ride. No fun if you're wondering if this is your last ride ....
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Old 02-15-10, 04:50 PM   #6
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The only thing I can say is why wouldn't you buy a $30 torque wrench before doing this? That just doesn't make sense at all.
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Old 02-15-10, 05:00 PM   #7
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The only thing I can say is why wouldn't you buy a $30 torque wrench before doing this? That just doesn't make sense at all.
I agree with you but in my case the reason I broke the steer tube was because I was using a torque wrench and the torque spec on the stem. Without the torque wrench I would not have broken the tube, in this particular case. I still use the Park 1/4" drive torque wrench on stems and other small parts but with better information and lots of intuition.
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Old 02-15-10, 07:34 PM   #8
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The only thing I can say is why wouldn't you buy a $30 torque wrench before doing this? That just doesn't make sense at all.
In my case, I had seen my bike mechanic adjust the headset (and retighten the stem bolts without a torque wrench). And I'd done it once before also without over-tightening (on the same steerer, last week, when I had moved two spacers). In my line of work as a piano technician, I have developed a pretty good feel for things as they tighten. Just missed it this time.
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Old 02-16-10, 01:46 AM   #9
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In my case, I had seen my bike mechanic adjust the headset (and retighten the stem bolts without a torque wrench). And I'd done it once before also without over-tightening (on the same steerer, last week, when I had moved two spacers). In my line of work as a piano technician, I have developed a pretty good feel for things as they tighten. Just missed it this time.
ah, makes sense. I never owned a torque wrench until I started buying light weight parts and started seeing torque specs printed on them. Even then, I bought them partially to try to be more exact w/ tightening, partially because I like tools 8-)
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Old 02-16-10, 01:55 AM   #10
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Originally Posted by Al1943 View Post
I agree with you but in my case the reason I broke the steer tube was because I was using a torque wrench and the torque spec on the stem. Without the torque wrench I would not have broken the tube, in this particular case. I still use the Park 1/4" drive torque wrench on stems and other small parts but with better information and lots of intuition.
Pretty expensive lesson. Numbers printed on the stem doesn't mean jack ****. It can't, if you just think about it for 30 seconds.
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