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RE: [ST] Found the discussion on Cupping



Where did you get this?  It's interesting.  Reading w/o the pics they're referencing isn't as good.  Can you provide a link?

-----Original Message-----
From: st-triumphnet.com-bounces@xxxxxxxxxxxxxxxxxxxx
[mailto:st-triumphnet.com-bounces@xxxxxxxxxxxxxxxxxxxx]On Behalf Of
Thfwsf@xxxxxxx
Sent: Friday, August 05, 2005 11:35 AM
To: st-triumphnet.com@xxxxxxxxxxxxxxxxxxxx
Subject: [ST] Found the discussion on Cupping


Here is what Matt H posted awhile ago regarding cupping:
*******
OK - I'll chime in here.  An excerpt:

"Cupping, which is more  accurately described as scalloping, is a natural
wear pattern on motorcycle  tires and it will always follow the tread
pattern. It is not a sign that you  have bad suspension parts. It merely
shows that your tire is indeed gripping  the road when you make turns
(thank you for that Mr. Tire!). This scalloping  takes place within the
side wear bands of a leaned motorcycle as discussed  earlier. The extreme
forces that come in to play when the bike is leaned in a  turn are what
produce the effect and when the wear becomes sufficient, one  will
experience vibration and noise when one banks into a turn on a  scalloped
tire. Upon examination of the pictures at left of our sample rear  Avon,
our dusted front VTX Dunlop D256, and the picture of our chalked  Dunlop
D206 one can see how the scalloping follows the tread pattern.  The
leading edge of the tread grips the road and the rubber is scuffed  off
the tire in that area causing a depression. As the tire rotates,  the
pressure moves to the trailing edge of the tread pattern and the  tire
flexes there which causes less scuffing so less material is ground  off
the tire. The more complex the tread pattern, the more complex  the
scalloping pattern will be. The softer the compound of the tire,  the
sooner this scalloping will become evident. Radial tires are more  prone
to cupping than are bias ply because the compound of radials is  more
often softer. As one can see, the simple tread pattern of the  Avon
pictured produces a simpler scalloped pattern while the more complex  VTX
D256 Dunlop is somewhat more involved, though still fairly easily  seen
in our photo. Scalloping on the Valkyrie Dunlop D206 is very hard  to
photograph because of the complex tread pattern. Improper balance  has
nothing to do with "cupping" on a motorcycle tire. Improper balance  will
merely cause your bike to vibrate within certain and specific  speed
ranges. Low tire pressure will exacerbate this wear pattern and you  will
lose many serviceable miles by running low."

*******
 
Tom


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