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Unusual tire wear

B

bigben974

Tricycle
When I removed my front pilot GT that lasted about 20 000 miles, I saw that the tire was not round anymore but more of a shape of a pentadecagon.
Does that indicate something wrong with the front suspension? too much or not enough preload maybe?
It also caused the bike to shake the steering to the point that I could not take the hands of the bars.
 
Yannick said:
When I removed my front pilot GT that lasted about 20 000 miles, I saw that the tire was not round anymore but more of a shape of a pentadecagon.
Does that indicate something wrong with the front suspension? too much or not enough preload maybe?
It also caused the bike to shake the steering to the point that I could not take the hands of the bars.
Click to expand...

Way too much geometry there pal!  15 sides?  No way due to the tire only (arguably) having 180 degrees of cross referenced surface area.  And 20k on a front tire? WOW! Me thinks all is good and you just ran that tire way too long!  However I'd check the wheel and head bearings out just to be sure.
 
Not sure about the 15 sides, but it was to give you an idea of what it looked like.  like a bunch of flat sides. Although while driving, it was smooth until I took the hands off. Now with the new tire, I don't have the shake anymore and the handle bar does not shake with the hands off.
 
Front tires can wear funny, sometimes from to low of air pressure, but as Bob pointed out If you've got 20K out of the front you've done good. Uneven wear can contribute to wobbling but you still might want to check the steering head bearings for looseness
 
Yannick said:
Not sure about the 15 sides, but it was to give you an idea of what it looked like.  like a bunch of flat sides. Although while driving, it was smooth until I took the hands off. Now with the new tire, I don't have the shake anymore and the handle bar does not shake with the hands off.
Click to expand...

Yeah, ain't new shoes great!  :beerchug:
 
Yannick, let me guess - you have curves where you live, and you like to enter those curves kinda fast.  http://forum.cog-online.org/Smileys/FantasticSmileys/wink.gif  You slow before entering, but here comes the clincher - if you are not on the throttle (holding it steady or accelerating, versus still having it closed off, which is in essence "braking", as you are decelerating, and decelerating is braking forces, but just not using the "brakes" for braking, per se), the bike is a heavy beast (sans rider), and that front tire is now absorbing the braking and the cornering forces, versus just (well, mostly just) the cornering forces. 

I used to be what I call a "late transitioner".  I would get about a 3d of the way through the curve before getting on the gas (taking it from closed, when I was using the brakes, to rolling it on), and I saw it in the "sawtooth" pattern on my edge of the tread (and most of the non-center tread).  I lived in Italy and my work was less than a half mile from there the flatlands shot up 6000 feet to become the "Italian Alps", also known as the Dolomites.  I had curve nirvana, and had a time or two I wore out the edges of a tire long before the center.  http://forum.cog-online.org/Smileys/FantasticSmileys/smiley.gif

When I refined my technique - slowed more and then used the throttle sooner, instead of heading in a bit too fast and being hesitant to get on the gas, because I knew I was a bit too "hot", I found my tire wear went away.

Sure, tire pressure (big aspect) and suspension settings (not as big of an aspect) add in there, but for me the deciding straw was "late braking", well, late on the throttle.

It took me some time, but I refined it to where I was on the gas (again, maintaining speed, or accelerating, or accelerating when in the curve) BEFORE I pressed to enter the turn.  In the MSF courses we used to teach "slow, look, roll".  Come to find out the slow didn't necessarily mean braking, it could mean decelerating.  Anything causing loss of speed is slowing.  Notice they didn't use "brake, loo, roll"?

Take a pencil, and put the eraser on the table.  Hold it at a 45 degree angle, and push it.  See how the eraser peels back?  More or less the same thing I was doing to my tires.

Mark
 
2linby said:
Yannick said:
Not sure about the 15 sides, but it was to give you an idea of what it looked like.  like a bunch of flat sides. Although while driving, it was smooth until I took the hands off. Now with the new tire, I don't have the shake anymore and the handle bar does not shake with the hands off.
Click to expand...

Yeah, ain't new shoes great!  :beerchug:
Click to expand...

:beerchug: :beerchug: :beerchug:

10-4.  Just put 10 miles on my new Avons!
 
Yeah Mike, I have curves where I live, and I like to to speed through it. I guess that's the way they wore, IDK.
Although last year, I had a problem with the stem head nut being loose. The font end was making noise at every little bump and the dealer did not even remove the cover to check it.
Thanks for all your thoughts, and yes, it is nice to have new shoes. :)
 
Having just had to toss out a very new tire due to cupping (what you're describing),  I can verify that a bike with loose steering stem bearings will eat front tires and cause bad vibrations. Too low air pressure makes it even worse.

If you search here, you can read a thread I started before I discovered through the members here that the front neck bearings need to be pretty darn tight on this model.

I learned so much that I was able to stop the shaking and cupping on my other bikes based on the same principle. And it's very easy, but go ahead and buy the $20 tool to do the job, save yourself a lot of effort.
 
would that be the right tool for the job?
http://www.amazon.com/POSSE-HOOK-WRENCH-STEERING-MOTORCYCLE/dp/B004MZSSVM
 
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