paging the handling-isti

Ok, what causes a high-speed wobble?

Took the SO commuter Bandit (600) out for a quick thrash to get some
fuel today. Over some fast, slightly bumpy, bends, got quite a wobble
going at high speeds. I've also noticed the same on the motorway, but
far less pronounced. The bike's all standard AFAIK - currently wearing a
bridgestone BT45 on the front and a Bridgestone I-dunno-what (Exedra??)
on the back. Can't detect any play or notchiness in the head bearings,
wheel bearings or swinging arm. The rear shock is very hard over bumps
even though it's on it's lowest pre-load setting. Tyre pressures are ok.

Ideas?

 

Ahem. Too much weight on the back can exacerbate a handling problem
TBH though I would not have thought a pillion would be a problem.

Well, I don't kow Bindits specifically but tyres or rear suspension
shagged or wrong tyre pressures are the usual suspects here. You don't
say what mileage the bike/tyres are.

Suspension: lowest pre-load does not mean softer suspension: in fact,
with a rising-rate linkage, it could actually mean harder suspension.

Here's a guess: if you've got it on its lowest setting and carrying a
pillion then the back of the bike could be much lower than it should,
which might upset the geometry and weight distribution but this
depends on the spring fitted (but you say its probably standard).

A Bindit expert will be along shortly.

 

<looks down at feet, shuffles>

Well I could do with losing a few lbs.

Bike's done about 30K miles, dunno about the tires. The rear one's a bit
squared off.

orly? I thought rising rate meant the spring rate got higher the more it
compressed? Therefore with the lowest pre-load on the softer part of the

I thought it may have been me tugging on the bars (no fairing), but some
experimenting would seem to indicate that ain't it.

 

Rear swingarm pivot jammed ?.

 

On a modern-ish bike? Tyres, always tyres. I would guess that the
rear has lost it's profile and is squared off.

 

Interesting. The rear has deffo squared off.

I'd better see if there's anything in the piggy bank.

 

Shot swinging arm bushes, overloaded luggage, duff tyre pressures,
knackered head races, shot rear shocks, shot wheel bearings,
incompatible tyres, mismatched tyre sizes, plus any combination of the
above and more.