dreaded speed wobbles

[ahmedbadat]

hi everyone does anyone else suffer from speed wobbles while cycling? every time I hit a bump at speed or descend quickly or if the wind is gusts or changes direction the bike starts wobbling badly and its really scary, whilst this is happening to me the guys around me don't seem to be suffering the same problem, its becoming a issue as I now don't have any confidence descending at all.

[DirtyFrank]

Have your steering head bearings checked out, could be loose or worn.

[ahmedbadat]

doubt the problem is the bike as it happens on my road and tri bike, I do use the same wheelset though

[David Marshall]

If you google "shimmy" or "high speed shimmy" you will find a lot written about it.  A number of things can cause it to happen, basically anything that sets the wave motion off so you will get any number of cures suggested.  Assuming nothing obviously wrong with the bike you can try anything likely to delay the onset of the motion - like changing the fork, wheels etc but I finally solved the problem on my bike by replacing the frame! Drastic but some bodies and frames just do not mesh together.  While riding you can brake the wave by doing something like gripping the top tube with your knees or lifting your bum off the saddle.

[Cheese]

Hi, You seem to be speaking out of my mouth twelve months ago. I have been struggling with this for a while and has actually lost bunches going downhill due to being afraid of sticking with high speed descends.

 

Had a couple of bad wobbles(Hospital bend (Argus), Down to Montagu(Double Century) some of the downhill section on 94.7)and as you mention the confidence goes.Luckily so far has never come down due to this.

 

There is a few things you can do. Squeese your top tube with your knees.(Most common advice)

Pedalling also assist but as this normally happens at 70km/h I sometimes feel I am making the bike unstable by doing this.

 

I did adjust my set up slightly to get a bit more weight on the front wheel, as from reading on the net the bike actually start to swivel around the steering tube. So try fiddling a bit.

You must also relax, which I know is not that easy to do when confidence is down to absorb the bumps etc.

I read that the human shiver frequency is the same of that of a bike going into speedwobble.

 

Then you have to practice going down hill, I have found I am a bit better already partly as I am staying on top of a 1 km hill @ 13% gives me practice going downhill everytime I go cycling.

But as you say confidence is a big thing as I went down this hill without any issues, but in my first race for few months last week I had a slight wobble at around 55km/hour during the start of the race when I was still nerbous. Did 70km/h later without any issues but at that stage the nervousness was gone.

 

Good Luck anyway,

[LOOK695]

doubt the problem is the bike as it happens on my road and tri bike, I do use the same wheelset though

Which wheels are you using?

[ahmedbadat]

Thanks for all the advice everyone, 30mm profile hed wheels, and i weigh 62kg

[Cheese]

I was thinking about maybe you are to heavy for wheels, but at 62 kg I can not see that that is the problem.

 

I would try to move my weight forward, and relax. Try to find more info on google etc and see what you can use.

[Capricorn]

what's your tyre width and pressure?

[ahmedbadat]

Thanks guys, ja i found not being tense or rigid does help, but pedaling seems to do more bad than good most times, will give the top tube squeeze a try first and see what happens

[ahmedbadat]

what's your tyre width and pressure?

23mm gatorskins, at 8bar

[Capricorn]

23mm gatorskins, at 8bar

 

Try lowering the tyre pressure in 0.5 bar decrements till you reach about 7bar. See if that helps delay onset of the vibrations. Do you know at which speed the vibrations started? is this consistent?

[ahmedbadat]

Not 100% sure till i check garmin or strava but i think around 60kph

[Supersix EVO]

Check your set-up. My wife had the same issues on a Pinarello Dogma. She wanted to stop cycling which forced me to change her bike to a Giant LIV ladies spesific which she is extremely happy with. When I changed her Pinarello setup to fit me, there was absolutely nothing wrong with it and no speed wobbles at all.

What is different between the Giant and Pinarello is :

1. Handlebar width  The Giant about 2cm narrower

2. The stem is slightly longer on the Giant

3. The angle of the head tube and fork is more relaxed on the Giant and not as straight down as the Pinarello. Pinarello and Bianchi are very similar

 

Hope this helps

[DIPSLICK]

CLEARLY I DONT RIDE FAST ENOUGH NEVAAAAA HAD A SPEED WOBBLE

[CubeD]

When it happens in motocross I shift my weight to the back of the bike and give more gas. To me it sounds like you could be putting too much weight over the front of your bike. I've never heard of this on MTB, and feel it could just be input into the bars from the rider. Shift your weight back, put your chest on your seat and hang your gat over the back wheel! In sandy conditions you want a light front end, and want to stay above the sand and ride in it, if you get me?

With MX bikes and suspension set-up (sorry for relating to MX but its still two wheels and the science is the same) if you set you bike up to corner like a beast, you lose high speed stability, so the steeper your head angle the better you will turn but the stability at high speeds is compromised. This is why DH bikes have slack head angles and long wheel bases for that stability.

One more thing is to not look at the ground in front of your wheel, look ahead, by looking down you will become unstable, by looking ahead you chose a line and have anticipated whats to come.

Hope this helps.