Bike shaking / oscillating under hard braking

[agilwolf]

Good day All

 

This past week-end, on two separate road bike rides, I had instances where under hard braking from high speed, on downhill sections, where the bike shook / oscillated violently.  This is the first time that I've experienced this and it is  a scary experience, especially with traffic around you.  Releasing the brakes resulted in the shaking / oscillating ceasing.  The bike has rim brakes.

 

What could be causing this?

 

Thank you in advance

 

Gerhard

[Eddy Gordo]

front or rear wheel or both?

could be loose hubs, calipers, or headset.

Edited December 21, 2020 by Eddy Gordo

[Lance Stephenson]

Good day All

 

This past week-end, on two separate road bike rides, I had instances where under hard braking from high speed, on downhill sections, where the bike shook / oscillated violently.  This is the first time that I've experienced this and it is  a scary experience, especially with traffic around you.  Releasing the brakes resulted in the shaking / oscillating ceasing.  The bike has rim brakes.

 

What could be causing this?

 

Thank you in advance

 

Gerhard

Your headset may be loose.

[agilwolf]

front or rear wheel or both?

could be loose hubs, calipers, or headset.

 

Both, but more rear, I'll check the headset.

[Jon0]

I had the same experience recently although mine was also on the flats.

 

Sent the bike back to giant twice and they finally replaced the headset and the issue is no more...

 

Check the wheels are on correctly could also be a cause.

[agilwolf]

Your headset may be loose.

 

Checked, headset bolt seemed a bit loose.  Loosened and retightened, I'll monitor on my next ride.

[agilwolf]

I had the same experience recently although mine was also on the flats.

 

Sent the bike back to giant twice and they finally replaced the headset and the issue is no more...

 

Check the wheels are on correctly could also be a cause.

 

I'll monitor the issue after I now retightened the headset bolt.  If it persists, I'll get the LBS and Distributor involved in the solution.

[Long Wheel Base]

Just for info, I personally can't confirm this but many others have said before, if you get that shake/oscillating then squeeze your knees against the top tube to stop the shake.

[Bateleur1]

Could many things.  In my case a few months ago it was a loosening spoke causing the wheel to be untrue

[agilwolf]

Just for info, I personally can't confirm this but many others have said before, if you get that shake/oscillating then squeeze your knees against the top tube to stop the shake.

 

Will try and remember thank you.

[agilwolf]

Could many things.  In my case a few months ago it was a loosening spoke causing the wheel to be untrue

 

There's a small "wobbly" spot on the rear wheel.  Will have it looked at.  My  trueing skills leaves a lot to be desired...

[King_Crispy]

There's a small "wobbly" spot on the rear wheel.  Will have it looked at.  My  trueing skills leaves a lot to be desired...

Send it in to be looked at before you break spokes or crash.

Prevention is better than cure.

[Kranswurm]

Just for info, I personally can't confirm this but many others have said before, if you get that shake/oscillating then squeeze your knees against the top tube to stop the shake.

That applies to a speed wobble going down hill

Not sure that a loose wheel,headset or even brake set will be remedied by that.

[mecheng89]

Headset on the front, or your brakes aren't set correctly (back and front). 

[Mojoman]

You may be exceeding the Maximum Permissible Frame Speed...
 

[Mook]

There's a small "wobbly" spot on the rear wheel.  Will have it looked at.  My  trueing skills leaves a lot to be desired...

This is your problem. Had a tiny dent on a front rim years ago and exactly the same happened. Lift the rear, spin the wheel and apply rear brake very slowly until the pad makes contact with the rim. You will immediately feel the uneven grip on the rim at the point where the brake surface is deformed.

Good luck