Granted, it is an older “flat” version, but it is 1/2" of carbon weave, which appears to be solid carbon. I have two cracks on either side of the stem bulge. My bike has less the 6k miles and it hasn’t really been ridden that hard. I have seen 1/2 carbon take 30k lbs of pressure and flex sailing around the world and so find it hard to believe that this bar is what it appears to be (solid carbon).
Any one know about the lay-up? It can’t be solid carbon, even a thick should weave would hold up better than that.
Any one know if the stem bulge is hollow? I think I will route out a channel across the bulge, running out the “wings” and fill it in with uni-directional carbon. I would appreciate any insight into the make up (as HED has never answered my emails.)
*What could cause it to break or crack? Overtightening of the stem clamps. Add in a lot of force on the brake-pods, a crack could develop.
A lot of force on the brake-pods? 1/2 solid carbon lay-up? An F1 car has about this much carbon for its brakes “brake-pods”!
It doesn’t seem that “overtightening” a solid piece of carbon/epoxy weave can really cause this problem. Besides, I can’t imagine how you could compress a 1.5" (solid?) carbon tube with a bike stem anyway! These are typical stress fracture/flexion-type cracks, running fore and aft right next to the bulge, which is about 1" away from the clamp’s bearing surface. This is a 1/2" of carbon lay-up at that point. You should be able to literally run it over with a truck. The bike has never been crashed very hard (one rolled tire at a turnaround.)
I have called and left messages at HED and never gotten a returned call.
It doesn’t seem that “overtightening” a solid piece of carbon/epoxy weave can really cause this problem. Besides, I can’t imagine how you could compress a 1.5" (solid?) carbon tube with a bike stem anyway!
**
**
It isn’t solid.
Very few (if any) carbon bike parts are solid. The vast majority are hollow. This is why it is always a good idea to use a torque wrench, so you don’t over-tighten bolts and damage any carbon parts.
Yeah, on closer inspection, this looks like it is 2 piece (top and bottom mated, not even a clearcoat weave around the whole this). But the “overtightening” (blame the user) doesn’t seem right. While convenient in that no can prove it didn’t happen; the longitudinal cracks are at the point of highest leverage on the bar and so are at the point of likeliest failure.
Actually carbon can and does break pretty easily and a torque wrench is a mist unless you liking paying for parts you break. Even if it wasn’t over torqued everything including our bodies eventually fails. With bike components the best you can hope is your buying from a manufacturer that experiences low failure rate percentages.
Can you tell me: What the break looked like Where it was in relation to the stem clamp If the carbon was deformed at the clamp If the clamp area showed any delam or damage How you know he overtightened the bolts?
clean snap right at the stem clamp. slighly jagged on the lower end where the snap ended, kind of tore off the bottom half but the top half was pretty clean. No deformation. No delamination. He said it was feeling loose so he tightened it with a multi-tool on a ride and didn’t want it to slip so he tightened it goog and hard.
ugh. But that is the difference between my cracks/break and his; mine are >1" away from the stem clamp, which shows no prbolem and the shape of the bars changes dramatically between the stem clamp “bulge” and the flat portion of the base bar. The area where mine is broken is clearly the area of highest stress, so would be the area to break first in any circumstance.
It is hard to imagine that these HED bars are actually hollow, as they are only 1/2" deep and they are pretty heavy! The cracks don’t show into a void. So I am really curious to know how they are made. Again, this seems like a very beefy area of carbon fiber! I will let you know. Thanks for the info.
Trust us–it’s hollow, or foam cored at most. Might I suggest doing 2 things? Take a photo of the spot (use flash) and send it to both ST and Hed. We might actually be able to discern something from it. A picture this time around is worth more than a 1000 words.