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Thread: Bike ‘weaving’ under heavy braking on track

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    Standard Member cropsprayer's Avatar
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    Bike ‘weaving’ under heavy braking on track

    My bike seems to have developed a weave from side to side under heavy braking on track. I know a certain amount is expected as the rear wheel lifts and I’m used to that but mine seems to have got noticeably worse all of a sudden to the point I am not braking as hard as I could and would like to.

    ive tried adding a bit more preload to the front forks but doesn’t make a difference. Any ideas?

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    Forum Moderator alex's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    Increase rear rebound to slow the weight transfer forwards.

    - Alex

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    Standard Member Zxcv12's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    Quote Originally Posted by cropsprayer View Post
    My bike seems to have developed a weave from side to side under heavy braking on track. I know a certain amount is expected as the rear wheel lifts and I’m used to that but mine seems to have got noticeably worse all of a sudden to the point I am not braking as hard as I could and would like to.

    ive tried adding a bit more preload to the front forks but doesn’t make a difference. Any ideas?
    What tyre pressure are you using on the front? And what tyres/condition?

  4. #4
    Standard Member cropsprayer's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    I’ve used both supercorsas and the 2018 compk slicks for the last couple
    of events I’ve done and had the issue with both. I run 30/31 hot for supercorsas and about 28/29 hot for the slicks.

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    2 YEAR PREMIER MEMBER r25sti's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    have you checked the headstock bearings and steering damper.

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    Forum Moderator alex's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    You're weaving cause you're braking harder with increased confidence.

    Try to remove weight from the bars (grip the tank) and aim to reduce weight transfer speed.

    Compression front, rebound rear. Its a seesaw. Just note what you change under braking can change corner exit behaviour too...

    Try braking with only one hand on the bars, the harder you can do it in a straight line the better you're supporting your weight elsewhere.

    - Alex
    Last edited by alex; 15th July 2018 at 08:23 PM.

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    1 YEAR PREMIER MEMBER bmwbadboy's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    I think what Alex saying is what you should do.

    I would also put a zip tie on a front leg at 25mm from bottom and check if you bottom out on front (meaning zip tie goes down to below 10mm)

    All in all it sounds like suspension issue.

    Sent from my Pixel 2 XL using Tapatalk

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    Standard Member cropsprayer's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    I use the stock steering damper and just have it wound fully on but not checked it or the headstock bearing so I’ll take a look. Is there an easy way to test the headstock bearing?

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    Standard Member cropsprayer's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    I did try that before increasing preload on the front as they were getting to within about 5mm of bottoming out. Now about 10mm after adjusting.

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    1 YEAR PREMIER MEMBER bmwbadboy's Avatar
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    Re: Bike ‘weaving’ under heavy braking on track

    What's the wear pattern on rear tire after sessions where you push hard ?

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