From: Nev.. on 11 May 2010 19:33
On 12/05/2010 7:52 AM, Moike wrote:
> Nev.. wrote:
>> On 11/05/2010 9:51 PM, bikerbetty wrote:
>>> The gravel there did seem to vary in depth - dunno if
>>> that had anything to do with it - and today Lemmiwinks put something
>>> on my
>>> blog to the effect that on corners (on gravel) you need to lean the bike
>>> but keep your body upright - maybe it was something to do with
>>> that??? Not
>> I think leaning the body and keeping the bike upright is a better
>> cornering policy for gravel road.
>> '08 DL1000K8
Probably for the same reason that road racers put their knee down when
cornering, better traction, improved CoG (if you stand up while you do
this - which also makes it easier to shift [more of] your body weight),
and bikes are easier to control/steer when they're vertical, and less
prone to having a nice lie down.
From: CrazyCam on 11 May 2010 19:45
> Marty H wrote:
>> to cut a long story short, you push the the bike to the side you want
>> to turn with you leaning off there other causing the centre of gravity
>> to be still 90 degree from the road, even though the bike/tyres are
>> learning to one side,
> If you could do that, the bike would fall over. Turning a corner on an
> in-line two-wheeled vehicle requires the COG to be moved toward the
> inside of the turn, otherwise turning forces applied at the tyre contact
> patches will cause the bike to topple over.
> For a given turn radius and speed, the angle between the COG and a
> vertical is pretty well fixed. leaning either the body or the bike
> while keeping the other upright can achieve this. Actually leaning the
> body outwards would require a more extreme lean ngle on the bike.
> Leaning both bike and body would seem to be a happy medium.
> I've heard people promote both the more gymnastic techniques, and I
> cannot see why one might be better than the other. The only practical
> difference would be down to the slightly different shape and geometry of
> the contact patches.
> I'd like to hear a credible argument for one case or the other.
OK, to turn a bike you have to have some sideways force acting through
the tyres to to road surface.
For most circumstances, leaning the bike and body more or less at the
same angle works just fine.
However, at times, one may want to have the bike leaning either more or
less than the rider's body.
Ripping round a nice smooth rack track on sticky tyres, one might well
(assuming one is fit enough) hang off to the inside of the turn, to
reduce the angle of the bike for a given corner, so that the tyres are
still maintaining a good contact patch, and one has the potential to go
faster than the rider basically just sitting upright relative to the bike.
OTOH, if you are faced with doing the MOST, to get your P-plates (in
NSW) on a Kwaka GPX or GPZ 250, to do the U-turn, you have to get the
bike leant over a fair degree, but you don't actually want to have much
speed on, so you lean your body away from the turn, pushing the bike
down under you, so the bike turns tightly, but at low speed, and,
hopefully, you don't fall over.
Make sense so far?
So, for example, when I get new tyres fitted, my scrubbing in technique
is to ride round turns, leaning outwards from the turn, thus
using/scrubbing more of the side of the tyres, but at a lower speed than
I'd normally take the turns.
>> there is no sidways force on the bike so the
>> tyres dont slip sideways (lowside)
It's not that there is no sideways force, only that the force is less,
because the turn is being taken slower.
> If there's no sideways force on the bike (and it can only be applied at
> the contact patches) it won't go round the corner. For a given speed
> and turning radius, the required sideways force is a fixed quantity.
Aye, but, if the turn radius is fixed, and you reduce the speed, then
you have less force required.
>> it made BT's road good for 100kmh+ for me
"Reduce the speed" is a relative term! :-)
On the smoother straight bits, I might have seen 70 or 80 on the speedo,
had I had the time to look, but the corners were taken a lot slower than
that, and I was leaning out from the turn.
>> 80% of riding on the dirt is mind over matter... yes, its hard to over
>> come, practise on a bike and body that doesnt mind falling over helps
>> (cause you will)
I agree about the mind over matter bit, but for some of us, whose bodies
are already having troubles with athletic things like walking, and even
standing up, our bodies just aren't interested in the option of falling
off a motorbike.
> That's 90% of the reason why I'm a dirt woose.
From: Peter on 12 May 2010 00:07
> it depends upon the bike.
The SV is not a dirt bike.
From: Les on 12 May 2010 01:10
On Wed, 12 May 2010 04:07:04 GMT, Peter <someone(a)microsoft.com> wrote:
>> it depends upon the bike.
>The SV is not a dirt bike.
Betty's is... it just loves to lay in the dirt / gravel :P
From: Diogenes on 12 May 2010 02:16
On Wed, 12 May 2010 16:11:18 +1000, Diogenes <cynic(a)society.sux.ok>
>As I said, you opinions are those of a lay person.
Oops... I meant to say "_my_ opinions are those of a lay person."