Can someone explain tire chatter to me?

What do they change to get rid of it?

 

If there was an easy answer, we wouldn't be talking about it. It's not like changing gearing.

 

You need Neil Spalding's book MotoGP Technology. Best I can describe it is if you ever drag raced and had a vehicle wheel hop. Similar to tire shake in Top Fuel. Except a race bike can do it with the front. Watch a top fuel car in slow motion and imagine a bike doing that at every corner on the brakes.

 

Chatter is when the tire is no longer rolling in constant contact but momentarily loses grip and regains grip repeatedly causing the tire to stutter or "chatter" across the pavement. The cause of the chatter is overworking the tire. Unfortunately the cure isn't all that easy. It could be a variety of issues resulting from geometry, suspension settings, to tire pressure.

 

You've seen the racks of tires at the track? Well when you aren't listening they trash talk each other trying to get that mental edge for the rider.

 

Basicj jist is the suspension loads up, and over loads the tire. Tire loses grip. As suspension and chassis unloads, the tire regains traction again and starts to load up the chasis and suspension, which inevitably repeats the process. Chassis flex als has some to do with it, since when the bike is cranked over that has as much to do with traction as the suspension itself does, or more even, as well as damping and even tire pressures.

Or at least that is how I understand it. I fought it some on the Michelin V front last year, and went to the slick front and it was "better" but not gone, and nothing I did could get rid of it. It would not quit until I opened the throttle and got weight off the front, but it was manageable.

 

winner

 

Too much grip. Tire grabs and releases a hundred times a second... just like when you're sliding something across a floor and it starts to vibrate. Chatter.

 

If you could develop a method to instantly diagnose the problem and fix tire chatter, you would be one popular guy.

 

Some bikes and chassis seem to be a bit more susceptible to it than others.

 

A longtime racer who taught me most of what I know about racing (and motorcycles in general) said the way to ride around the problem is to feed in a little throttle to transfer weight from the front to the rear, just like you said.

It took me years to work up the balls to actually do it, even though I noticed that reducing the throttle mid-turn made it worse.

 

thanks op:up:

 

Since there is too much grip obvious answer is put a dab of armour-all on the tire

 

Silly, that won't work.

What they need to do is to make the wheels lighter.

I know this guy who made his lighter. His name is Shervin. He knows a lot about how to make motorcycles better.

 

Fat kid theory. Too much fat kid on the front or the rear causes problems.

 

The coefficient of friction between asphalt and rubber increases with force being applied down on the tires. Rubber has a unique characteristic, where once too much force is applied, the coefficient of friction actually decreases. This starts as chatter, then can lead to sliding. This is what I remember from reading some of Kevin Cameron's old writings.

 

sometimes adding a pound or three of air will lessen or eliminate the chatter .

this is of course at the expense of the grip that brought the chatter about in the first place .

if your machine only chatters in one or two corners , try changing your line and see if it goes away . try going faster , alot faster , and see if that works .

as stated above , more throttle may help but this requires you to be precise , have a set of nuts that work and follow through after commiting to such silliness but may not be possible in all corners .

i find it harder to run across chatter then apply more steam than to just go in faster and maintain .

side note ,chatter can be really fun when the front chatters so bad that it transfers through the whole bike and the front and rear start chattering violently and the whole machine is running wide , trust me , going faster did not help at all in this case but the corner in the opposite direction coming up did .

it amazing how much most of us have in "reserve" , going faster usually does the trick

also you must be certain of head bearing , wheel bearing , and swingarm bearings being in good condintion and adusted properly . go loosen your headset just 1/2 turn and try that out for fun

 

I have never experienced it on my 600, but my Motard chatters something fierce going into turn one at Jennings. I'm giving it all she can handle and I'm sure more speed in that specific case will be disaster.

 

but may not be possible in all corners