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ST-1100 News, Issue #002 -- Steering Wobble


November 15, 2010


ST-1100 News - November 2010


Welcome to the November edition of the ST-1100 News.
In this issue:
Autumn is upon us
The causes of Weave and Wobble


Keep your bike in good repair: motorcycle boots are not comfortable for walking. - Unknown


Autumn

November in the northern Hemisphere means autumn is here. The days are getting shorter, and the countryside changes colour to reds and browns.

Of course this beautiful scene changes again very shortly, when the lovely red and brown leaves fall off the trees. They've got to go somewhere - and especially on the back roads they can accumulate to form a carpet. Be careful when riding through this. Compressed leaves can be very slippery.


Causes of weave and wobble

There's nothing more disconcerting than suddenly experiencing a front-end wobble at highway speeds. You start wondering about what could possibly have gone wrong and what you're going to need to do to get it fixed. There are a few possible causes: a problem with the motorcycle, the rider, or the road conditions.

In my previous life as an IT Consultant, a logical approach has certainly assisted me in troubleshooting when things go wrong. The first question to ask is, "What's changed?"

  • Perhaps you've had a new front tyre fitted? (Others have reported problems on fitting the latest Avon Storm Ultra). I contacted Avon about this and received a reply from their Motorcycle Technical Product Manager:
    "The change from Storm ST to Storm 2 Ultra incorporated a lot of technical changes mainly to the rear tyre, this included newer multi-compound treads, carcass and belts. The front tyres changed less in regards to construction (which would affect head shake). I would guess that it may be a tyre uniformity issue rather than the change to Storm 2. Some bikes (the ST1100 in particular) are sensitive to front tyres. We have recently reduced the pass limit for tyres leaving the factory which should resolve any issues."
    So, if you have a new Storm 2 Ultra front tyre and experience any headshake, take it back to the dealer and ask for a replacement. If they refuse, you can always quote the Sale of Goods Act 1979, which states that goods must be "as described", "of satisfactory quality", and "fit for purpose".
  • Perhaps the tyre is not mounted on the rim properly.
  • The wheel could be out of balance.
  • Tyres could be worn or have incorrect pressures
Generally if a headshake occurs within the 30-50 mph range, then check for flaws in front of the steering head i.e. tyres, brake rotor etc.
If your wobbling occurs at speeds over 65 mph, then check for defects behind the steering i.e. steering head bearings. It's advisable to replace them with tapered roller bearings as described here.
  • I've also seen it written that if you've overfilled the crankcase with oil, this will result in vibration as well. This is nonsense. The writer was reporting verbatim something he'd heard without really understanding it. If you overfill one side of the front forks with oil, you can get a shaking effect, because they're unbalanced.
  • "Death grip". This is the phenomenon caused by gripping the handlebars far too tightly especially when throttling out of a corner. Try to loosen up your arms and keep your hands relaxed.

Other causes, although unlikely, could be:

  • Chassis not straight
  • Brake rotor bent/warped
  • Front and rear wheels misaligned
  • Too much flex in the front fork, chassis, or swingarm
  • Front end lower than rear

The motorcycle rider and how they handle road conditions are also major issues with shaky steering of motorcycles. The rider may not know how to keep the bike steady in all conditions and this will cause shaky steering on any motorcycle. The traffic and road conditions provide you with multiple variables to consider while riding your motorcycle. You have to know your bike's strengths and weaknesses as well as your own. You have to know how to properly handle your bike and to adapt to situations beyond your controls. If you know that you or your bike can't handle the vibrations of a sharp turn, then don't take try to take a curve at 80 mph. Riding a motorcycle can be an exercise in itself if you don't know what you're doing. Controlling the motorcycle can be tiring for some riders and they may be too fatigued to control the bike and keep it aligned to stop the shaking.


November Tip:

Just because the weather's getting colder doesn't mean you get to skimp on washing the motorcycle! Keeping your bike clean is the most important maintenance you can do. It prevents corrosion and lets you spot any obvious problems.


Keep the shiny side up.

Rob


In the next issue: Tools and Toolkits - what tools do you really need to carry?



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