RE: [ST] for Matt and Richard - tire width & cornering

["Masiak, Richard" <Richard_Masiak@xxxxxxxxxxxxxxxx>]

Don,

Ahhh, I'm beginning to better understand.  That also explains the risk of high siding.  If the rear tire begins to slide further out the arc, the arc is now putting the rear outside the front.  So when the rear grabs traction again it will still want to bring the front in the rear's direction or pull it (I think) in the direction the rear was going hence snapping the bike up and throwing me, er the rider over the other side.

Seems like there's no way to totally prevent it, just reduce the risk of it happening by trying to keep the arc differential between the front and rear as close as possible without making the rear go outside the front arc..

Now that we've opened pandora's box, let me ask another question.

How is that done?  To keep the rear arc as close as I can to the front arc, do I slide the rear or reduce the lean angle by hanging off more? or alittle of both?

Rich

- -----Original Message-----
From: owner-st@xxxxxxxxxx [mailto:owner-st@xxxxxxxxxx]On Behalf Of don
draper
Sent: Monday, November 15, 2004 11:21 PM
To: ST@xxxxxxxxxxxxxx
Subject: [ST] for Matt and Richard - tire width & cornering

<SNIP>
 Because the rear tire is on an arc inside that of the front, it's
vector of force is at an angle tangential to the arc and it tries to
push the front wheel straight ahead towards the outside of the
corner; this is UNDERSTEER, which is commonly known as PUSH.  This
causes the bike to drift wide in the corner and limits the amount of
power you can use.  Obviously the greater the difference in radius
between the two arcs, the harder the front will be pushed.  Because
the contact patch in a turn is on the inside edge of your tires, the
wider you go on the rear with the same front, the greater will be the
difference in radius and the worse understeer you'll get.  Watching
racers powering out of corners, you'll see the front tires leaving
black streaks on the pavement,... they're being pushed sideways while
being laid over.  You may not want to try this at home,... or with
your own bike!    =8o) 
<SNIP>

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