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Strange Sensation?


zxsixter
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Im new here... But was hoping to get some good feedback to what Im feeling..

Slightly before my knee touches down, the bike feels like the both tires are rolling over an edge? or hitting a diffrent angle on the tire? (PP's) ..Almost like it starts turning in faster at a certian point.?? Kinda hard to explain I guess. Its pretty nerve racking at times.. Im not sure if the tires are about to give out or what? And thats my main concern, that im at the verge of a lowside. Is this a normal feeling? Im hanging off as far as possible, im as loose as i can make myself so i know its not input on the bars. Its definetly something at a certain lean angle??

I know this is a prety vauge question but any help would be great to ease my mind..

Oh ya bike is a 08 zx6...

 

Thanks Again

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Im new here... But was hoping to get some good feedback to what Im feeling..

Slightly before my knee touches down, the bike feels like the both tires are rolling over an edge? or hitting a diffrent angle on the tire? (PP's) ..Almost like it starts turning in faster at a certian point.?? Kinda hard to explain I guess. Its pretty nerve racking at times.. Im not sure if the tires are about to give out or what? And thats my main concern, that im at the verge of a lowside. Is this a normal feeling? Im hanging off as far as possible, im as loose as i can make myself so i know its not input on the bars. Its definetly something at a certain lean angle??

I know this is a prety vauge question but any help would be great to ease my mind..

Oh ya bike is a 08 zx6...

 

Thanks Again

I am not sure, but it could be related to the profile of the Pilot Powers. They do have a slightly more angular shape to them compared to the rounder shape of pirellis or bridgestones, which could make it dip in faster. Also could be related to tire pressure, what pressures are you running?

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Is it pilot powers 2ct, if so you may be feeling the softer compound at the side taking hold!

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  • 2 weeks later...

I've used those tires a lot and I like them. I have an '06 gsxr-600. I've also used the same tires on a YZF600R.

 

How worn out are they? I've found that on any tire, if I use them on the street a lot, there's a certain lean angle I'm comfortable with on the street, and the profile of the front tire eventually develops a flat spot at that lean angle, which messes with the handling. When at that lean angle that's using the flat spot, the contact patch is wide, and that makes the bike want to stand up, but then when it gets passed that angle, the contact patch is narrow again, and that makes the bike want to lean down more. Seems like what you are describing. Even though my rear tires usually wear out twice as fast as the fronts, I usually replace the front tire with the back for this reason.

 

If you are used to some other tire then it could be the profile. They do make the steering feel a little different from other tires but I never had the feeling of it about to lowside. You didn't answer what pressure you are running. I run them about 30 on the track, but sometimes a lot higher on the street.

 

I wonder if your problem might have something to do with suspension? Cornering forces will cause your suspension to compress. Maybe you should try increasing the preload on the front. Have you ever checked the sag?

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The Pilot Power fron is pretty netural and shouldn't feel like it is really falling in when you lean it over.

 

I agree with the above post in that i would question the wear on the front tire. If it is pretty flat in the middle from a lot of highway riding that would cetainly cause the feeling your experiencing.

 

In any case I don't think what you are feeling is a loss of traction.

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I've used those tires a lot and I like them. I have an '06 gsxr-600. I've also used the same tires on a YZF600R.

 

How worn out are they? I've found that on any tire, if I use them on the street a lot, there's a certain lean angle I'm comfortable with on the street, and the profile of the front tire eventually develops a flat spot at that lean angle, which messes with the handling. When at that lean angle that's using the flat spot, the contact patch is wide, and that makes the bike want to stand up, but then when it gets passed that angle, the contact patch is narrow again, and that makes the bike want to lean down more. Seems like what you are describing. Even though my rear tires usually wear out twice as fast as the fronts, I usually replace the front tire with the back for this reason.

 

If you are used to some other tire then it could be the profile. They do make the steering feel a little different from other tires but I never had the feeling of it about to lowside. You didn't answer what pressure you are running. I run them about 30 on the track, but sometimes a lot higher on the street.

 

I wonder if your problem might have something to do with suspension? Cornering forces will cause your suspension to compress. Maybe you should try increasing the preload on the front. Have you ever checked the sag?

 

 

The tires were surprisingly low.... 25psi cold f&R.. <_< I bumped them up to 30psi and it seemed to help very little... The tires are fairly worn... (Will be changed for the pp race med f&r for my 1st track day this spring...) Heres a pic of the tire..

 

 

tire.jpg

 

 

 

 

 

Here is a good pic of roughly the angle Im at when the sensation occurs?? Im wondering if its me starting to hang onto the bars a little to tight and giving it some bad input??????

 

 

IMG_55633.jpg

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You posted a pic of your rear tire but the phenomenon I was talking about was more to do with the front tire. Anyway it does sound like a fresh front tire is very likely to help. And meanwhile, as long as there is rubber on that tire, I'm not suggesting that you have to rush out and replace it. I normally do like you are doing and wait until just before a track day to put on the fresh tires.

 

I've been through a lot of tires on street bikes on public roads, commuting and touring, and the wear pattern I always see is that the rear tire wears out in the middle, but the front tire wears out somewhere between the extreme edge and the middle, because that's the part of the tire getting used the most in my more moderate public road lean angles. And when the tire gets to be in this condition, the normal neutral handling gets all messed up - I am forced to keep pressure on the bars to get the bike to hold those moderate lean angles, it tries to stand up out of the turn and I have to fight it, but then if I lean lower and get passed that flat worn part of the tire more towards the edge, the bike becomes neutral again. That transition from having to push on the bars to neutral handling feels exactly like you described. The front tire in this condition also causes some wobbling on bumpy/swoopy roads, so it just all around starts to suck when it gets bad enough.

 

The following is just my theory/understanding as to why this happens:

If you roll a coffee cup on a table it will curve instead of rolling straight, because the bottom of the cup as a smaller radius than the top of the cup. The tires on motorcycles, when leaned over, are affected the same way, causing the front wheel to want to turn toward the inside of the turn which would make the bike stand up. Normally this is canceled out or balanced out by the trail. "Trail" as you probably know is what keeps the front wheels of a grocery cart pointed in the correct direction, and it is also used on the front end of a motorcycle for basically the same purpose - it keeps the front wheel pointed in the direction that maintains balance or neutral handling. "Neutral handling" means the bike will maintain its lean angle with no pressure on the bars. When the front tire is worn as described above, and you reach the lean angle that uses that worn part of the tire, the contact patch becomes wider, which means that coffee cup effect gets more leverage, which causes the front tire to want to turn into the turn and drive itself under the bike, or in other words makes the bike want to stand up instead of maintain its lean angle.

 

When I have a front tire that's seen a significant amount of track time I don't have this problem, because on the track I'm wearing out the very edge. But for so many reasons I just don't see those kinds of lean angles often (or ever) on the street.

 

>> Im wondering if its me starting to hang onto the bars a little to tight and giving it some bad input??????

 

You could put your bike on a repair stand, or maybe just the side stand, then get on and get in your hang off position, then let go of handlebars, you should be able to hold your body in the hang off position with your hands not even on the bars. Then the more difficult thing is to make sure that is true at all times through the turns. I have often found myself reverting back to supporting some weight on the inside handlebar. When ya hit bumps or swoops in the middle of turns that weight on the inside bar may cause the bike to wobble some, and that's what always alerts me that I'm doing it. I like riding on rougher back roads as practice because they force me to be very conscious of staying loose on the bars. The harder ya ride the more noticeable it is. It could be that at certain lean angles you are hanging off your shoulders more, and/or starting to put more weight or pressure on that inside handlebar which would cause the sensation you describe.

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I know your problem well. The deal is that it's the wear of the tire. The flat part one aquires during use changes the shape of the tire. When you get past the flat patch, and standard wear that occurs when you do slow or frequent cornering, the tire acts differently. When you're on the outer edge, that part doesn't have contact much, so it's still shaped for what the tire is designed to do. Smooth lean.

I LOVE new tires because the bike rolls where ever I want to go, and easily. Takes a few corners because it's such a smooth transition to lean that it kind of freaks me out, and gives me the feeling that I'm "rolling over an edge." I'm sure, judging by your pic, that you are familiar with tire slippage. It feels completely different. That rolling feeling is also something that I forget when it's been a while since I've mounted some new rubber. Now I want some new tires.

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I know your problem well. The deal is that it's the wear of the tire. The flat part one aquires during use changes the shape of the tire. When you get past the flat patch, and standard wear that occurs when you do slow or frequent cornering, the tire acts differently. When you're on the outer edge, that part doesn't have contact much, so it's still shaped for what the tire is designed to do. Smooth lean.

I LOVE new tires because the bike rolls where ever I want to go, and easily. Takes a few corners because it's such a smooth transition to lean that it kind of freaks me out, and gives me the feeling that I'm "rolling over an edge." I'm sure, judging by your pic, that you are familiar with tire slippage. It feels completely different. That rolling feeling is also something that I forget when it's been a while since I've mounted some new rubber. Now I want some new tires.

 

Thanks Guys... This sounds like this could be the case... I'll know for sure June 17th when the PP race mediums go on and attempt my first track day.. I cant wait..

So with all your guys experience should I have another set of tires ready to mount up after a track day? or should the PPR tires last another 1000 miles of street riding after the fact? Im a total newb to this, Ive only been riding for 8 months on the street. (All my life in the dirt though..)

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Here's another post about the same problem, with similar responses:

"Once I Get Past A Certain Lean-angle, The Bike Wants To Keep On Leanin"

http://forums.superbikeschool.com/index.ph...pic=869&hl=

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I have used the regular Pilot Powers on the track, for 3 to 4 track days back to back no problem, they had plenty of tread left for a couple thousand miles of street use after that. I liked them on the track because, at least for someone of my level, they seemed to provide very consistent performance for 3 or 4 days, and they also work fine on the street. So if that model is significantly less expensive than the race version you might want to consider just getting a fresh set of those. I've not used the Race version but I seriously doubt you are going to fry those in one day of track riding unless you are famous.

 

Here's an excerpt from Keith's article "The Bands of Traction" in the Keith's Corner section of the forum:

Everyone wants to have the stickiest rubber they can afford but it isn’t sticky until they can put the big load on the tires. Most riders would do better and learn heaps more about traction with something lesser than full race, factory rider developed tires. Why? They don’t have to put the big loads on the tires to start to experience the bands of traction as listed above.

 

Look at it this way. If you are using the tire at the bottom end of where it was developed by pro riders would it actually save you if you got brave for a moment? The answer is no. Pushing the loads on the tires up for a moment when the rest of the lap was at your normal pace will not give the tire enough time to warm up to the level you momentarily demand from it to handle the situation.

 

In other words, your potential and that of the tires have to come up together for you to take advantage of what the tire has to offer. To a large degree, the security of the stickiest rubber is false. Until you arrive at some consistency in your levels of speed and lean angle and throttle control and the other technical parts of riding it is no more then blind faith.

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I've used those tires a lot and I like them. I have an '06 gsxr-600. I've also used the same tires on a YZF600R.

 

How worn out are they? I've found that on any tire, if I use them on the street a lot, there's a certain lean angle I'm comfortable with on the street, and the profile of the front tire eventually develops a flat spot at that lean angle, which messes with the handling. When at that lean angle that's using the flat spot, the contact patch is wide, and that makes the bike want to stand up, but then when it gets passed that angle, the contact patch is narrow again, and that makes the bike want to lean down more. Seems like what you are describing. Even though my rear tires usually wear out twice as fast as the fronts, I usually replace the front tire with the back for this reason.

 

If you are used to some other tire then it could be the profile. They do make the steering feel a little different from other tires but I never had the feeling of it about to lowside. You didn't answer what pressure you are running. I run them about 30 on the track, but sometimes a lot higher on the street.

 

I wonder if your problem might have something to do with suspension? Cornering forces will cause your suspension to compress. Maybe you should try increasing the preload on the front. Have you ever checked the sag?

 

I've experienced the same feeling, and chalked it up to the same theory. New tires was the cure for me.

 

I did my first track day on street tires (Metzler M1s) and they gave me great feedback, and I could tell by the end of the day when I was starting to push them harder and started to feel them move around more.

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So knowing the PP race tires should last.. Ive heard that its not a good idea to run them on the street? So is it best to have another set of street tires ready to swap on after the trackday?

I commute on the same bike I track, and have Pilot Powers. I don't ride as hard as most here, but I need a new set about every 6 moths, which is 6-8 trackdays and 80-90 miles of road riding a week.

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