Hed H3 Carbons and speed wobbles

Triathlon Forum
1

Hey all,

Requesting a bit of advice / feedback.

I ride a 2005 , 53cm LitespeedBlade , full Dura-Ace , Cane Creek C-2 Headset with Hed H3 Carbon wheels.

I use a Vision Tech base bar , with R-Bend clip-ons.

Forks are Real Design Aero HP Carbon.

Yes , I also use a Profile aerobottle upfront.

My wheels are stored ( hanging ) in wheel bags until one week before races , where I take them out and ride a couple of hours to make sure they are ok.

I use the prescribed ceramic carbon brakes.

I continually get high speed wobbles in slight crosswinds. The wobbles get so violent that I have had my gel bottle on the top tube , thrown off.

I actually pulled out of my last race 6 days ago due to this problem , and a blown front tubular.

I am aware that these wheels do present a larger side profile ( with the aerobottle as well ) adding to increased instability in cross winds , but it really does seem excessive.

I am 5.9’ ,155 lbs and ride 115-120PSI on tubulars that never have more than 3-400km’s.

Temperatures ( in 2 separate races ) were 33C and 27C.

My LBS, states the wheel is true and both front and back wheels, are aligned as straight as my eyes can tell anyway , the night prior to the races.

I will be racing in 9 days time , but will be using my Hed Alp on the front ,until I can get a confirmation of the problem.

I will include a couple of pics of the set-up, as taken in a race pic in February.

I appreciate any constructive criticism that is given.

Thanks very much in advance.

Terry :slight_smile:

http://im1.shutterfly.com/procserv/47b7dd07b3127cce83407fb8188000000015100AatWLRy2atWKg http://im1.shutterfly.com/procserv/47b7dd07b3127cce83407c9f583e00000016100AatWLRy2atWKg

2

Hi, I have raced HED 3c in both Ironman CDA and IMUK and they were very windy and rough roads! I think you should pump your Tubs up the the recommened pressure of 140-160 as that will help with any wobbles! Also if it starts to happen clamp your knees on the top tube this will stop the wobble.

They are definatly the fastest wheels in all conditions you need to be agressive with them and your lighter wieght may be a little bit of the problem!’
Cheers!

3

Hey mate,

That is a good point about my weight though , but like you say the tire pressure may be too low. Normally the conditions are stifling hot and you will get increased pressure from resistance on the hot road. But I am unsure as to just how much extra.

I used to weigh 180lbs so I guess this is one disadvantage :slight_smile:

Thank you for your reply and advice.

4

No idea what is specifically wrong but something in that setup is sending you into a crazy harmonic wobble in your range of speed so you basically need to do something to change things up.

Read slowman’s article on the main page but generally you can fix pretty much any speed wobble that’s not a mechanical problem by changing your body position and/or riding technique.

I doubt it’s a mechanical problem but things that I’m thinking might worsen the wobbles could be:
-really imbalanced wheel, maybe too long of a valve stem, really messed up tire, placing a heavy valve cap on the valve
-old, notched up headset
-maybe too short of a stem as this makes the steering a bit more sensitive

anyways, good luck

5

Thank you Tai , I will check into all of these points with my LBS.

  • The tire valve stem ( gap ) was taped over with black mechanical tapetight and perfectly flat. Only over the gap though with care not to be close to the braking surface. No valve cap is on the valve. It was perfectly undisturbed until I ripped it off after my tire blew.

  • Headset was replaced in January with a brand new one , 6 weeks prior to IM Malaysia where I encountered the first speed wobble at 55-60km/hr.

  • Length of stem …hmmmmm. I am pretty far forward , that is for sure.

Thanks again Tai.

Terry

6

no problem, anyways, it’s probably body position or you’re tensing up or something at speed. practice the knees to top tube trick or shifting your body weight around, staying loose in the arms and stuff like that

7

Here is some advice which might help you …
http://yarchive.net/bike/shimmy.html

Frank

8

Probably the only way to sort this out is to get a friend, find a hill that will constantly start a wobble and switch front wheels. If your friend also wobbles on his bike, you’ve found the problem.

If it is the wheel, try remounting your tires or a new one, if it still wobbles; call Hed.

9

I sustained a speed wobble last year at Timberman while riding with an H3 on the front; frightened the hell out of me. I’ve tried other “aero” wheels at the front and they’ve all been sketchy. I’ve finally come to the conclusion that the only way to go downhill fast is to use a much less aero wheel; no unstability so my confidence goes way up and I go faster. Is this solution perfect? No, but it works for me.

10

Here is some advice which might help you …
http://yarchive.net/bike/shimmy.html

Frank
Thanks very much Frank, lots of points in there !

11

Probably the only way to sort this out is to get a friend, find a hill that will constantly start a wobble and switch front wheels. If your friend also wobbles on his bike, you’ve found the problem.

If it is the wheel, try remounting your tires or a new one, if it still wobbles; call Hed.

The problem wheel is a Hed H3 Carbon.
Tomorrow I will ride a windy straight road with the HED H3 Carbon on the back and my Hed Alp on the front. I will also include the aerobottle.

I will be unable to ride the actual identical route ( of the speed wobble in the race ) in the near future, as it is actually in another country. In 2 weeks time I will test the Hed H3 Carbon front wheel as well with the identical race set-up that the wobble occured. I have managed to get up to 55km/hr on this nearby windy straight road with my training wheels so " hopefully" I will be able to identify the determing factor once the local Hed agent takes a look at the wheel and I get a new tire on it.

I train on Mavic Ksyrium’s and have NEVER encountered a speed wobble on the same hills as I raced on this past weekend. Additionally I probably even went faster on the training wheels because as soon as It started wobbling I stopeed peddling and moved from aero to upright.

I should have mentioned ,that when the speed wobble occured ,I conciously disregarded the brakes ,as the road was one lane each way , I was descending and 300m later would have started to ascend. It happened as I returned on the same road going the opposite direction descending again. The descent is not steep. I would think about 7 degrees.

Thanks for your advice , I appreciate it.

12

I sustained a speed wobble last year at Timberman while riding with an H3 on the front; frightened the hell out of me. I’ve tried other “aero” wheels at the front and they’ve all been sketchy. I’ve finally come to the conclusion that the only way to go downhill fast is to use a much less aero wheel; no unstability so my confidence goes way up and I go faster. Is this solution perfect? No, but it works for me.

Norton…Thanks for your reply and glad to hear you came out unscathed as well.

After having this happen during IM Malaysia in February this year 5km’s into the bike , whilst descending in the 50-early 60’s , I’ve had 6 months to reflect on how lucky I was. I also realize that I lost probably 20-30 mins from descending cautiously as opposed to descending as I would normally.

When this happened at the 15km point and then about 5km’s later it really pissed me off. We all train hard and when you have something out of your control, limit your speed ,per se , the day just depreciates from a race day to a training day. 45 mins later the front tire blew and I officially chalked up my first DNF.

As I wrote earlier , my training wheels would have been…just fine :slight_smile:

13

I’ve had HED3’s up to 50mph while descending without a problem. I’d bet that its your position on the bike. Appears that you ride well forward. Next time it starts try a few different positions, ie. moving slightly back taking weight off that front wheel, and/or really loosening your grip. If you have a death grip on the bars it makes things much worse. Barely hold the bars and allow the front end to make the neccessary minute adjustments it needs to make on its own.

I see myself “wandering” a good 3-5 feet side to side as I descend at high speeds with cross winds. Best thing to do is “let it happen”. Don’t fight it, allow the bike to track as it sees fit under the conditions.

Hope this helps, at least a little.

14

We’ve decided that it is the H3 mounted to your bike causing the wobble, but before calling Hed; it’d be best to determine whether it is your setup/positioning used in conjunction with the Hed 3c or specifically that Hed 3c. Many people use this wheel without problems. I use a Hed 3 tubular and have not experienced this. I’d like to think that this could be fixed by getting a replacement wheel through Hed, but without eliminating all variables; I doubt they’d just send a wheel out.

15

I’ve been doing some reading on the H3. I read in some other threads that these wheels have shims that must be adjusted in order to “true” the wheel/ensure that it follows a straight path. Try putting your bike on a repair stand, crank it up and see if you get a lot of wobble (a little wobble in the right place is great, but not on a bike ;P). A wobble bad enough to eject a bottle or make you drop you dentures sounds mechanical to me and not due to position. Check for wobble in the cassette as well, that could indicate that the freehub body is bent. That last one is just a wild guess.

16

Paul

I do ride well forward and often right on the end. My coach highlighted something to me in training in January this year and something you are stating as well. Relax the grip and just lightly grasp the bars. It was not told to me because I was guilty of death grip , but more as an additional point of relaxation and energy conservation.
I do relax most of the time ,although I may subconciuosly "tighten up "with crosswinds. I know I do, occasionally increase my grip when mashing up inclines.

Regarding the “wandering” side to side. The road that this took place on is one lane each way and dirt on the sides. I am probably more concerned about drifting than I should be. Swimming is my weakest discipline and in most races I usually play catch up on the bike. Good advice on the “let it happen” , I will follow that thanks.

Well as I type this I just see the clock has added another year to my resume 41…damn where do the years go ?

Goodnight all and thanks for the responses , my wife will sleep better now :slight_smile:

17

Mudflaps

Excellent points , thanks. I will ensure my LBS folows that to a “T”.

Thanks a lot :slight_smile:

18

Something I’ve noticed while reading this post. Tires have blown 2 times after the wobble. Those who have experienced this wobble (i have yet to) what kind of tires do you use? Tubular Or Clincher? If tubular who glued them on, and what kind of glue? How light are the wheels? I don’t think it is limited to h3s either

I used to be a mechanic in my prior life, and any vibration at high speeds was caused 90% of the time by imbalance of a tire, followed by a defective tire. On a Bike, if the front rim is light weight, almost any unbalanced weight will cause a vibration. i bet if you put suspect wheel on a Wheel balancer (automotive kind) it would show an imbalance.

I think any extra glue, a tire patch, or even a low spot on the tire (caused by improper balance) could cause a wobble.

19

The tire never blew in the first incident in February.

The second and third incidents happened on similiar , but not exact roads , under cooler conditions , last Saturday.

Hed H3 Carbons only come in Tubular ( there is no clincher model available ).

Continental sprinter 27" 22mm Tubular.
Glue is Continental Special Rim Cement

The tires were glued on by my LBS who I have utmost confidence in. Without going into details I would not blame them at all. They are fanatically meticulous with their work , but of course …it is possible that they were slightly out of line.

I just returned from testing the Hed Alp on the front now, with the Hed H3 Carbon on the back.
I only managed to get up to 49km/hr, butthe wheel bike was as solid as rock with no vibrations whatsoever.
I forgot to attach my aerobottle and there was no crosswinds.

I will re-test again tomorrow with aerobottle and I will bring along the HED H3 Carbon front wheel ( with a new tire on ) as well as my training wheel. I will play around with all 3.

Is it possible to bring it and request to have it put on an automotive wheel balancer machine ? Would those types of machines accomodate such wheels.

I am sure the Continental automotive tire distributor here would have the machine. Great idea , thanks very much !

20

I’m going to suggest another approach and that is to try a disc on the rear with the H3. This will move the center of pressure more to the rear and make the bike more stable in high winds. Yes, I said more stable, try it, it works. I’ve never ridden the H3 but I ride a Zipp808 with a disc and find it much more stable in the wind than I was with two 404’s.