I had my first trackday this week [moto], had a lot of fun but now notice some small lumps of rubber on the tire. I was kind of surprised to see my bike (M695) was capable of blistering the tires (BT016) so much, but I wonder if the lumps are something to worry about.
(http://i366.photobucket.com/albums/oo108/IdZer0/rear2.jpg)(http://i366.photobucket.com/albums/oo108/IdZer0/rear.jpg)
(http://i366.photobucket.com/albums/oo108/IdZer0/reardetail.jpg)(http://i366.photobucket.com/albums/oo108/IdZer0/reardetail2.jpg)
Anyone ever seen this before? Could this be just pile of melted rubber which has bonded with the tire again after cooling?
That's just rubber you picked up on the track. Don't worry about it. Completely normal. That said, the last photo (it's hard to tell) might be some cold tearing of the tire. Again, don't really worry about it.
Thx Spidey.
I read up on some tire tech and cold tear is definetly possible. I was running 35 psi in the back, which in hindsight is probably to high.
Track school recommends 29 psi in back, next time I'll try that ;D
Quote from: IdZer0 on May 07, 2009, 01:29:06 PM
Thx Spidey.
I read up on some tire tech and cold tear is definetly possible. I was running 35 psi in the back, which in hindsight is probably to high.
Track school recommends 29 psi in back, next time I'll try that ;D
Yow. 35 is waaaaay to high for the track. I'm glad you didn't fall down. If you don't know the specific track psi for your tires, 30f/30r is a good baseline. 29 psi rear will probably be fine too.
Your psi also explains some of the wear on your tire. The chicken strips in your pic are not just from lack of leaning the bike. You had the tire pressure up too high, which kept the tires from flexing as much. When they flex less, you get less meat on the side of the tire as your contact patch when you're leaned (as a general rule). If you lower the pressures, you'll find that your chicken strips will get smaller as the tire flexes more under load.
NOTE: this is track tire advice. For anyone reading this, don't lower your pressures on the street to try to get rid of chicken strips. It won't work, you'll fall down, and we'll all tell you you're an idiot. ;D
Was there a suspension or a tire guy at the track day? Next time, have the guy set up your suspension for you. After that, run a session or two and then go back to the guy and show him your tires. He may be able to read your tires and give you some advice about suspension and/or pressures. Show your tires to the tire guy as well. He may be able to give you some feedback. There's no other way to learn this stuff well.
If you're interested, Dave Moss, a local suspension guru has a buncha videos on Youtube about reading tire wear. Search for Dave Moss or Catalyst Reactions. It's a lot more info than you're lookin' for, but it's a good way of nerding out about tires. Here's one his vids. I think it's mainly about suspension, but he gives an example of how to read tires: Suspension Setup on the Track (http://www.youtube.com/watch?v=brRDwt4Q2kQ#ws-lq-lq2-hq-vhq)
Quote from: Spidey on May 07, 2009, 01:41:13 PM
Yow. 35 is waaaaay to high for the track. I'm glad you didn't fall down.
Didn't realize 5 psi would make _that_ much difference.
I don't know about a suspension guy at the track. I did a course together with some 58 people, and they didn't pay a lot of attention to tires & suspension except say you could buy some tires there. Don't know if they're more interested in selling rather than giving advice, but I'll check them out next time.
Great info from the video(s). I crave that stuff; makes me understand my bike a bit better.
thx for the advice.
definitely looks like cold tear to me...
suspension set up and pressures will make a night and day difference in your track experience.
I wish I had a pic of the tire I took off the 996.
I don't see cold tear in those pics.
Maybe I need a couple more pairs of glasses. :-\
If my understanding of what cold tear is and what it looks like, then it should be the 'rippling' of rubber (what I wrongfully called blistering in the initial post) you see in the second pic between the center of the tire (with some dust on it) and the chicken strips. Is that correct?
I have the inverse of what's in the video: a lip on the trailing edge. Don't know yet what that means for the suspension, I'll be looking at some youtube films.
I hope my understanding of what trailing and what leading is is correct. If you take the 2 edges of a groove, the one that contacts the ground first is the leading one and the one after the groove is the trailing one, right?
So it's: surface - leading edge - groove - trailing edge - surface - leading edge - groove - trailing edge - surface
Cold tearing as I understand it is rubber gone from the tire.
My 996 had a groove about 1/8" deep where you're mentioning.
Then I need to reread the tech stuff :-[ . And it means it is not cold tear as there are no grooves, just the lumps in the middle and the rough texture on the side.
Man it's hard to express yourself about these technical matters if you're not a native English speaker
I know all this suspension stuff and tire stuff is cool to geek out on, but if I were you, I'd be focusing my reading and research on the basics -- lines, body position and the most basic suspension set-up. Your time is better spent on other stuff. Stuff like cold tearing and tire reading and small changes to tire wear are more advanced topics that--frankly--you shouldn't worry about for now. If you're just starting to do trackdays, the best thing for your tire wear is have your suspensio nset up, work your body position, and take smart, smooth lines.
That said, if ya just want to geek on this stuff, go for it. [thumbsup]