I’ve been using my Hed 3 for the last couple of months (but only a handful of times because it’s winter here). I currently have it on a Giant composite TCR. TCR’s are notoriously twitchy on downhills anyway but I’m finding with the Hed 3 that when I get above 35mph I have to come of the aerobars because the front end feels too unstable. I was running a spinergy deep section before and this was fine. Is it just me needing to spend more time with it or is there something else I need to do ?
Do you have a disc on the rear? That stabilizes any bike I’ve ever ridden with an H3 front…including a Giant TCR I used to have. BTW, I weigh in the low 180’s, if you’re lighter…well, you’re going to be blown around more.
Make sure your headset is nice and tight. I had a problem simular to what you described and it was do to a loose headset. The front end would become very unstable at high speeds.
Do you have the wheel mounted in the correct direction? I believe the design of the spokes (tear drop) creates lift (like an airplane) if mounted in the wrong direction.
From the published windtunnel tests of the old Specialized 3-spokes you can see that the design exhibits a change of the sign of the torque exerted on the fork for increasing yaw angles. Meaning that in a gust of wind, the increasing wind velocity will increase the yaw angle and the torque exerted will be first in one (twisting) direction and then the opposite.
…so depending on the fork and it’s rigidity, will depend on the feel as speed and yaw angle change ?
Fork rigidity won’t affect yaw angle significantly. What might affect more the way you feel the instability is headtube angle and rake.
I have actually heard about this before. Ves Mandaric explained that sometimes people experience a wobbly or twitchy front end with a Hed3 that goes away when you use a wheel with more spokes (like the spinergy). I think it has more to do with the fork and how the fork handles the turbulence created by using a wheel with three large spokes. The twitchy sensation is pretty much always caused by vibrations, and if the turbulance is causing the fork to vibrate, this is going to get passed on to the front end and the frame. You might find that the knee on the top tube trick helps reduce this.
Oh, I am assuming this is on descents, when you are not pedaling against resistance (which also reduces the vibration).
Check out Cobb’s site. He has an article there that explains wheel torque which is what is sounds like you are experiencing (H3s can exhibit both positive and negative torque depending on the yaw angle).
OT
Uh… no, that’s not it at all 
I traded my HED3 front for a HED Alps because I used to get speed wobbles all the time. My LBS tested the rim and determined that there was a heavy spot / dead spot that was throwing the wheel into a tizzy! It was terrible… but I’m much better now.
I’ve had the same problem. Not sure of the cause but have given up trying to ride it as a front wheel because of all the instability it creates while descending. The wheel is fast and stable on flat courses and even windy flat courses but if you try to descend on one it can be scary. It happened to me several times and 31 mph was the magic speed for me. Has nothing to do with Bike handling skills, your weight or your bike, I’m 6’3" and weigh around 205. have been over 50 mph’s countless times on my Cannondale riding some of the descents the Tour de Georgia will use this year without ever having my bike wobble. However with the H3 on the front it’s almost out of control. Never had any problems with the rear.
How about not using aerobars on a road bike like the Giant TCR which is not meant to be used with aero bars?
"How about not using aerobars on a road bike like the Giant TCR which is not meant to be used with aero bars? "
The Giant TCR makes a GREAT TT bike with aero bars, just not with a forwrad saddle position. Ask Laurent Jalabert and the ONCE team.
So should I put off getting a front H3 and get an Alps instead??
Seems strange that everyone raves about the H3 but then multiple people have had problems above 30mph. Or does riding a H3 with a disk make this problem go away?
Mike
I had some scary sensations without a disc on the rear…but not since then. I used to have a deeper dish front wheel, but, I couldn’t keep it trued…the H3 hit a bomb-crater and had no noticeable damage/side effects…and I’m stable on it when on a disc, so, I won’t be changing…even when it’s windy.
"The Giant TCR makes a GREAT TT bike with aero bars, just not with a forwrad saddle position. Ask Laurent Jalabert and the ONCE team. "
Laurent Jalaber good at TT come on. Once Team did not use the TCR but a time trial bike that is not currently being sold.
“Laurent Jalaber good at TT come on.”
Guess who won the 1997 World Time Trial Championship.
“yaw angles”? “torque”? I love it when you guys start talking like that…
Someday I hope to publish a “guy” dictionary for women. Flange. Cam. Fairing…
“Wobble” I can understand.
Leigh
Leigh, Flange, cam, fairing that sounds more like a guys dictionary of women than the other way around 
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