handlebar wobble?

i have just fitted a rear luggage rack and a top box to my yamaha sr125.i have noticed that when i get some speed up that there is a slight vibration on the steering.when i lighten my grip on the handlebars it starts to shake.is it something to do with the rack and box weight or is it something to do with the airodynamics being altered.it didn't do it before the box and rack were fitted

10 Answers

  • 1 decade ago
    Favourite answer

    Since the weight issue was mentioned already, I will speak to the aerodynamics first.

    My friend had a bike with a top case installed after about a year. The rear top case caused the bike to lean, ever so lightly to the right when at high speeds.

    We removed the box and re-tested, the lean was not present. This test however, was at 65MPH. How fast are you going when you feel this?

    Normally, a 'wobble' is due to the rider sitting back, shifting all their weight to the rear. The front will begin to .... shimmy (sp) if you will, and when you drop the weight back to the front/center the wobble will begin. Normally a slow coast (drop in speed) will help reduce the wobble, and regain control.

    I would tell you to remove the case (if possible) to make sure the case is in fact the cause of your wobble. Ride the same route to test it.

    If confirmed, the case on gets the wobble and no case installed does not... add weight in the form of a sand bag to the bars, test again.

    On a personal note, I had a VFR and added a top case to the rear. Had over 40lbs of cargo in it... never an issue with a wobble.

    Source(s): 14 years riding.
  • Anonymous
    1 decade ago

    To give a good baseline, in order to see if the box can be made to work, first adjust your rear preload to compensate for the extra weight. Make sure your tires are in good condition and properly inflated. Check for worn, loose or notchy head stem bearings. Make sure your wheels are aligned.

    If you're still wobbling, try raising the front forks in the triple tree slightly.

  • 1 decade ago

    commonly referred to as highspeed wobbles. Usually reserved for bigger bikes at higher speeds.

    Here's what you did. you put a luggage rack on a bike that weighs almost nothing to begin with. Then you put a box on it.

    Both of these are behind the rear axe.

    Do an experiment at home to better understand. Take a pencil, balance it on your finger going across. Once it is balanced, with your free hand, drop a paperclip on one end of the pencil, what happens to the other end?

    Same with your bike. It is not a bike designed to be carrying weight back there, suspension is not set up for it. if you have adjustable rear shocks, but them on the stiffest setting, this may help, if you don't.........well, you see the problem, you have lightened the front end by making the rear heavier.

    Sometimes you just have to bite the bullet and graduate to that bigger bike to do all the things you want to do.

    Least you know where the wobbles are coming from now.

  • J.
    Lv 5
    1 decade ago

    Its the box and rack that's causing the problems.Other than

    removing them your best bet is to move further forwards on

    you bike nearer the fuel tank to compensate for the added weight at the rear.

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  • 1 decade ago

    Erm could be the box is too far out from the rear end causing the fron th be ligh when the box is fully loaded- or your over loading hthe box.

    But i would check :

    -front tyre isnt worn funny/ got a flat spot

    -Front rim isnt buckled

    -front wheel bearings arnt knotchy or loose

    -front brake isnt dragging/ warped disc/drum

    -Forks are shot- worn springs, leaking oil/ none!

    -steering head bearings arnt loose, knotchy

    - swinging arm bushes

    - rear shocks arnt shot

    - rear tyre and wheel and its bearings

  • 1 decade ago

    Small bikes would get steering wobble due to the tyres ..check the tyre wear and the pressure of both tyres.

    You could also check to see if one of your front folks is leaking at the fork seal.

    Source(s): 35 years as a biker and I dont mean a fair weather rider
  • 1 decade ago

    you have altered the bikes weight ratio by adding the rack and top box, simple fix adjust or add steering damper to front end

  • Ray K
    Lv 5
    1 decade ago

    I would guess that lower weight on the front might be it. However, bigger bikes (and maybe yours) have steering dampeners that prevent wobble up front. Check yours to see if it's bad or ask the dealer if they sell aftermarket ones for your bike.

    Source(s): X test rider
  • 1 decade ago

    Experiment with changing the tire pressure of each tire, a couple of PSI at a time, to see if that will make a difference.

  • 1 decade ago

    weight distribution is bad due to the added wind resistance , maybe hang a midget across your front fender it will balance things.

    Source(s): im a midget
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