Speed wobble

[Shaunpr]

I seem to catch a speed wobble around the same area on a pretty fast decent, the bike goes into a serious wobble, the first time I used brakes to slow down but it actually made it worse so now I try peddle through it. What would be the cause of this and what can I do to stop it from happening. The bike is sized right for me so I am puzzled and pretty scared too.

[Spinnekop]

9/10 times you can get out of the wobble by just pressing your knees against the top tube.
Weird I know, but it works.

[Butterbean]

Clamp the top tube with your knees, it'll stop...

[Spinnekop]

I have heard MANY theories over the years.  Frame size, headset issue, wheel issue.
Can be any of the above.  But to get out of the wobble......knees against the top tube like you would if you were kicked in the groin.  

[eddy]

Typically it is a matter of harmonics.

 

Dampening it by clamping the toptube with your knees solves the problem. 

[Jewbacca]

A good way to negotiate that is to lower your centre of gravity, so actually take all pressure off the saddle, lean the bike to one side and press down hard on the opposite pedal, like you would cornering, but go straight.

 

The higher up your weight from the contact points to the road, the more wobble.

[Long Wheel Base]

A good way to negotiate that is to lower your centre of gravity, so actually take all pressure off the saddle, lean the bike to one side and press down hard on the opposite pedal, like you would cornering, but go straight.

 

The higher up your weight from the contact points to the road, the more wobble.

While science says this should work, I would be damn scared to try it

[Jewbacca]

While science says this should work, I would be damn scared to try it

I suppose the timing and precision needed to get this right on a tandem would be akin to Synchronized swimming!

 

I lean the bike a lot, it feels super planted. Even if you just get one pedal below the BB and hover over the saddle it should do the trick.

[Shaunpr]

While science says this should work, I would be damn scared to try it

I can say it is freakishly scary. But lets try the options mentioned

[Dirt Tracker]

I had a really bad one one that started when I hit a certain speed going down on suikerbossie and damn near killed me. This was just after I had new tyres put on and they hadn't been seated correctly on the rear and that actually had them out bowing out a tiny bit at one spot. They were tubeless road tyres and the shop had to pull them apart and reinstall them. You could see a tyre / wheel do a little wobble when you held it up and span it fast. I guess at 70km odd going down that little thing turned into mayhem! 

Edited September 7, 2020 by Dirt Tracker

[Pure Savage]

What speed does the speed wobble start? 

[Vetseun]

My tits wobble when I run

[Shaunpr]

What speed does the speed wobble start? 

Around 50km/h plus

[Grey Hubs]

My tits wobble when I run

Do you use your hands or knees to stop the wobble?

[Bateleur1]

My tits wobble when I run

 

A good tight fitting sports bra should sort that out.

[Pure Savage]

Around 50km/h plus

Flip thats not fast at all. Maybe check if wheels are 100% True. thats really scary.