Cornering question: heavy or light bike best ?

[GrinningGSer]

In the two years and 13000miles of 1200GS ownership, I have ridden everywhere with 3 boxes, partially because I will feel safer in a slide with the boxes on

These three boxes are very heavy and last Sunday I went for a ride in a very blowy monsoon... without the boxes. The bike felt uncomfortably light and totally at the mercy of violent cross winds. Rear wheel seemed to skip everywhere.

Gosh the 1200 is a different, very light beast unladen and I have to say that I feel safer and more planted with more weight.

So can anyone with more knowledge tell me if a bike has better cornering grip laden or unladen ?

 

[cookie]

the lighter the better as far as i'm concerned.

 

[Mzokk]

The lighter the better. The three boxes will catch the wind like a sail and a top box is even worse as it catches wind at a height which gives a mechanical advantage for rocking the bike about.

 

[terayon]

When you took the boxes off did you adjust the suspension to take into account that you weren't carrying extra weight. Having your suspension preload up too much would cause the tyres to skip on the road

 

[ovenpaa]

When you took the boxes off did you adjust the suspension to take into account that you weren't carrying extra weight. Having your suspension preload up too much would cause the tyres to skip on the road

I always have my rear preload set to max less quarter turn regardless of what is on the back, and tyres set to two up pressures and never really notice any difference (1150 Adv) If anything it would mean the bike would turn in a bit quicker as the back end is jacked up.

As far as weight is concerned a heavy bike does take some lugging through faster sequences of corners and can run a little wide but this is more down to the chassis characteristics and suspension/tyre setup and choice. We are talking about GS's here, they handle quite well.

 

[Shep]

Lots of things come into effect when you take panniers off

Big boxes can act like a dart flight in cross winds, they can have a stabilising effect. Also the weight on the back of the bike will lower the back to give slower steering, remove the weight and the angle of the forks steepen and so the steering can get more choppy IYKWIM. The "windage" on a non encumbered bike is centered more middle to front on the bike, as luggage is fitted the pressure is more even.

Secret is to adjust your suspention accordingly and give yourself time with the new set up.

Light bikes corner faster, change direction quicker, heavy bikes are more stable and slower to turn and if the fatty gets out of shape they take allot of getting back, whereas with the lightweight you may just stand a chance of recovery

Shep JMOOCYU

 

[Lou Can]

Theoretically a heavy bike will have greater grip, in terms of friction, since the frictional coefficient is a ratio of the force down verus the force across. Increase the force down (i.e. the mass) and the frictional coefficient rises giving more grip (all other things being equal).

However, the centripetal acceleration generated through cornering (i.e. the force across) is defined by mass, speed and radius of curve so a heavier bike will generate a proportionally larger force. In reality the mass is likely to have less of an effect on the centripetal acceleration than the friction since in the centripetal form it is bound into an axpression involving the square of the velocity, so plays a minor role.

Therefore, for a given corner, speed, tyre compound etc. a heavy bike has more grip. The other factor - effectively drag from wind or airstreams - is essentially aerodynamics and will depend on the design of the bike i.e. its "slab-sided ness". The force generated by such cross winds will be defined by the area it can push against. The effect will be defined by the inertia of the machine. Again - heavy bike less likely to be affected.

The downside is that a heavy bike will be less keen to change direction so it will be slower to manouever through corners and harder to get back on track if the wind does manage to deflect it.

LC

 

[Timolgra]

Big boxes can act like a dart flight in cross winds, they can have a stabilising effect.

You mean like a pair of 'drone' anchors

 

[Greg Masters]

So can anyone with more knowledge tell me if a bike has better cornering grip laden or unladen ?

Do you mean roadholding or handling?

Some vehicles are highly controllable through bends with no unanticipated behavioural traits, but actually can't corner that quickly.

Others have very high levels of grip but handle abysmally.



Greg

 

[ovenpaa]

Do you mean roadholding or handling?

Some vehicles are highly controllable through bends with no unanticipated behavioural traits, but actually can't corner that quickly.

Others have very high levels of grip but handle abysmally.

My RRT Fireblade springs to mind here, it came with 600 miles on the clock and a revalved front end, Penske shock on the back but used to shake the front end very badly through flat out second and third gear corners, yet always felt very well planted and never let me down, right up to the day I wrote it off....

(White van driver one, David nil)

 

[(RIP) Kaister]

In the two years and 13000miles of 1200GS ownership, I have ridden everywhere with 3 boxes, ......

These three boxes are very heavy and last Sunday I went for a ride in a very blowy monsoon... without the boxes. The bike felt uncomfortably light and totally at the mercy of violent cross winds. Rear wheel seemed to skip everywhere.

So can anyone with more knowledge tell me if a bike has better cornering grip laden or unladen ?

its what you're used to.

take the boxes off and its 'relatively lighter'

still a barge though compared to a zzr600 for instance.

keep riding and you'll get used to it