High Speed Death-Wobble
08-04-02, 02:41 PM
#1
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High Speed Death-Wobble
Has anyone had a "high speed death-wobble" happen to them on a new specialized road bike. It happened to me going down a steep hill over 40km/h, the front end started wobbling and I almost went over the front end. It happened on a new specialized road bike. I asked a friend and he has had it happen twice this year. Does anyone have any comments or has this happend to anyone else before?
08-04-02, 02:46 PM
#2
I can remark on one possible solution if it develops: put your knee against the top tube to "damp" the harmonics that are causing the wobble. It's not specific to a brand of bicycle or even two of the same brand & model. Sorry to hear your bike is afflicted! 
08-04-02, 02:48 PM
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Ya the wobble is really in the fork, I almost think thew new Carbon Fiber is too light and not stiff enough, it wasn't the bars or the headset that was wobbling.
08-04-02, 02:53 PM
#4
My old lightweight-steel Fuji Team would do the shimmy if I rode no-hands at certain speeds with an aero bar bolted on. Without the aero bar, it didn't. It had a Kestrel EMS carbon fork, which was a darn stiff fork IMHO.
08-04-02, 05:34 PM
#5
Fool O' crap
The same thing happened to me because of the death grip I had on my bars. I had rode MTN bikes for years, the first ride on a road bike I thought I was going to die (it happened to be a Specalized as well), my front end went crazy, shaking all over. A roadie I ride with told me to lighten my grip on the bars - and it went away.
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08-04-02, 07:27 PM
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Kind of off topic, but I've been meaning to mention it... For God's sake, if you've got aero-bars, don't use them while you're descending!!! I see so many people flying down the local hilly course on the bars. Their hands are so far from the brakes, and the position is so unstable if emergency maneuvering is required that they'll often be unable to avoid trouble (locally that could mean a deer in the middle of the road). Sorry, just a pet peeve - and I've got a pair of Profiles on my bike BTW.
08-04-02, 07:32 PM
#8
LOL, you're not going to like this... I've cracked 55mph/90kph into a sweeping left corner on my aero bar 
sscyco and other Spokane residents probably know this descent, generally called "Big Sandy." Even a 53x11 on 700C wheels isn't enough to put power on at that speed or I could probably have gone faster.
Mind you, I'm not disagreeing that it would have been very bad to have a blowout in that situation.
sscyco and other Spokane residents probably know this descent, generally called "Big Sandy." Even a 53x11 on 700C wheels isn't enough to put power on at that speed or I could probably have gone faster. Mind you, I'm not disagreeing that it would have been very bad to have a blowout in that situation.
08-04-02, 08:06 PM
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What are the factors that create these harmonics and wobbles? I have an old Specialized MTB set up for road touring. I only have a wobble when riding hands free above about 17 mph, and only if I have a load on the rear rack! It goes away when the load is removed. It goes away with the lightest of hand pressure on the bars, or top tube pressure. I can't get rid of the wobble by leaning forward, which would argue against front end load being the issue.
Any thoughts on causes?
john waldron
rice lake wisconsin
Any thoughts on causes?
john waldron
rice lake wisconsin
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08-04-02, 10:20 PM
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08-05-02, 02:20 AM
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I know little about this wobble, but 40 kmh sounds awfully low to start having the wobble. I have usually heard of it happening around 70-80 kmh. After all, even amateur racing runs at speeds around 40 kmh on the flats.
In short, I would definitely have this checked out. My bike (all steel) has kinda twitchy steering, but I have never had it wobble at any speed (I've hit probably just above 80kmh).
Does anyone know if this is a common problem with carbon forks?
Cheers,
Jamie
In short, I would definitely have this checked out. My bike (all steel) has kinda twitchy steering, but I have never had it wobble at any speed (I've hit probably just above 80kmh).
Does anyone know if this is a common problem with carbon forks?
Cheers,
Jamie
08-05-02, 05:38 AM
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Life with a metastable vehicle. All two wheel vehicles will eventually demonstrate "speed wobble", where the combination of harmonics causes an increasing vibration that eventually becomes uncontrollable. It can be tires or even bent spokes. It can have an aerodynamic contributing cause.
My only experience with is was on a motorcyle at about 95 mph, talk about cheap thrills, boy the grass looked soft. In my case it turned out to be tire related.
My only experience with is was on a motorcyle at about 95 mph, talk about cheap thrills, boy the grass looked soft. In my case it turned out to be tire related.
