Speed Wobble and hand position.

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Speed Wobble and hand position.

Postby Gearoidmuar » Sat Jun 14, 2014 12:38 pm

A couple of years ago I got a horrific speed wobble on a westerly descent to the west of Schull Co.Cork, during a triathlon relay. It was so bad I almost crashed and having stopped the bike I was convinced until I saw otherwise, that the frame was fractured. In 30 years of cycling I'd never experienced its equal.

Last Saturday I took part in the same triathlon relay and again the wobble started (this is the only hill on which this bike has wobbled. It's very fast and irregularly surfaced). I know the tricks to correct the wobble. I shifted forward, reduced but not gone, gripped top tube with knees, not gone. Sat on nose of saddle, nearly gone but not gone. But then, shifted hands to forward area of drops, nearly gone, hands on hoods, completely gone. During the sequence I repeated all these positions. Hands on drops straight down, immediate wobble and even gripping very loosely the same thing. Gripping rounded surfaces of drops, much less, hoods, totally gone.

I've never seen this documented like this but others may have experienced the same but not communicated.

It may be that the grip on the hoods is naturally very loose..

Has anyone an explanantion?
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Re: Speed Wobble and hand position.

Postby NATURAL ANKLING » Sat Jun 14, 2014 4:42 pm

Hi,
Sounds like steering issue as hands far forward on hoods give better damping do to better leverage.
Controversial subject, too little or too much trail, tyres, tall rider..............
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Re: Speed Wobble and hand position.

Postby Gearoidmuar » Sat Jun 14, 2014 4:45 pm

Different tyres on both occasions, same cyclist, same height but 2 stone lighter.
Whatever it was, it's useful to know that among the tricks to master is different hand position...
Last edited by Gearoidmuar on Sun Jun 15, 2014 10:00 am, edited 1 time in total.
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Re: Speed Wobble and hand position.

Postby rjb » Sat Jun 14, 2014 9:12 pm

Hats off to you for trying something different - on the odd occasion i have experienced it i have been scared too witless to try anything apart from gripping the top tube between my legs. I probably grip the bars tighter and tense up but i find it impossible to relax under these circumstances - self preservation comes into play and i pull on the brakes tighter until i come to a standstill or get it under control.
:shock: :shock: :shock: :shock: :shock:
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Re: Speed Wobble and hand position.

Postby Norman H » Wed Jun 18, 2014 12:22 pm

I can't help much with an explanation but I'd be interested to know what hill west of Schull you're talking about. I'll be riding my road bike that way next week and I'll be back later in the year for some loaded touring.
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Re: Speed Wobble and hand position.

Postby Gearoidmuar » Wed Jun 18, 2014 5:26 pm

Norman H wrote:I can't help much with an explanation but I'd be interested to know what hill west of Schull you're talking about. I'll be riding my road bike that way next week and I'll be back later in the year for some loaded touring.


You climb out of Schull on the Goleen road and it's the first long descent. You'll know! It's a bit of a bucking bronco of a ride at speed.
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Re: Speed Wobble and hand position.

Postby Norman H » Wed Jun 18, 2014 8:51 pm

I've cycled that road on several occasions and never had a problem. It probably helps that I ride a smallish frame and I only weigh around 56 Kilos.

It's interesting that the incidents that you experienced were two years apart. From your other long running thread I presume you were somewhat heavier on the first occasion.
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Re: Speed Wobble and hand position.

Postby NATURAL ANKLING » Wed Jun 18, 2014 9:48 pm

Hi,
Interesting............47 years on many junk bikes, I have never had a wobble, on unmotorised two wheels.

I weekly do 46 - 50 mph on my touring bike on some very bumpy roads and can hardly keep my hands on the bars for bumps but no wobbles despite the bike and me weighing in at a shade under 100 kgs.

Its a resonance thing which needs certain speed and frequency of bumps / steering trail with certain section tyres / weight distribution on the wheels.
Bigger section tyres increase the trail, and some will say the drag on steering which dampens out instability :?:
26-04 -14- 76 KGS - 16-12-14 78KGS...(:<((
Breakfast...one toast and jam......rumble...(:<((
......
Roadies are fair game......especially when I am on my MTB. 21 Notches - 10 ? +/- a Hybrid (:<((
If It Seems Easy Then Change Gear.
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Re: Speed Wobble and hand position.

Postby Gearoidmuar » Thu Jun 19, 2014 8:19 am

NATURAL ANKLING wrote:Hi,
Interesting............47 years on many junk bikes, I have never had a wobble, on unmotorised two wheels.

I weekly do 46 - 50 mph on my touring bike on some very bumpy roads and can hardly keep my hands on the bars for bumps but no wobbles despite the bike and me weighing in at a shade under 100 kgs.

Its a resonance thing which needs certain speed and frequency of bumps / steering trail with certain section tyres / weight distribution on the wheels.
Bigger section tyres increase the trail, and some will say the drag on steering which dampens out instability :?:


I can vouch for that! The only other bike I've had mild wobbles on is my current touring bike, a Thorn Raven Tour. I rode it for a couple of years with Specialized Fatboy tyres which are narrow for it. I used to get an occasional wobble. I switched to fatter tyres (Big Apple), not for that purpose at all, but the result is a rock-steady bike even at high speed. Discussing it with another tourist, he told me that narrower tyres had made his Dawes Galaxy unstable..
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Re: Speed Wobble and hand position.

Postby reohn2 » Thu Jun 19, 2014 2:49 pm

FWIW,I used to have a bike that didn't like Schwalbe Marathon H308's if I tried to ride no hands,various TP's didn't make any difference.
I could never feel it through my hands on the 'bars but if left hands off,it would've brought me off.
Slick tyres Gatorskins,solved the problem.
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Re: Speed Wobble and hand position.

Postby Pete Jack » Wed Jun 25, 2014 12:25 pm

I have a Specialized Roubaix that got a fierce wobble at about 40 mph. Scary. The knee gripping thing fixed it. The road surface was quite good. The front wheel has a Gatorskin, the back has a Panaracer Pasela I got cheap. I don't often go at 40 mph but I've felt a tremor at about 35mph since then. IIRC my hands were on the hoods when I got the bad wobble.
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Re: Speed Wobble and hand position.

Postby Gearoidmuar » Thu Jun 26, 2014 9:53 am

Pete Jack wrote:. IIRC my hands were on the hoods when I got the bad wobble.


You would've been lucky then. Had they been on the lower drops you'd have been shaken not stirred!
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