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My front tire has cupping on the left side, the right is seemingly fine or less noticeable. Is this caused by less aggressive lean angles to the left, or a suspension, or alignment issue?

I rode in hard left turns for 20 minutes in a parking lot, seems to be better, but would like to know how it happened in the first place. I just got this bike 2 days ago, need to make it perfect again, lol
 

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Assuming you have ME 880 tires, some say running low on air pressure. IE, 42 front 48 rear will certainly reduce cupping. The book says a lot less but causes cupping really quick.

Not real sure why you would get cupping on just one side.

The Guru's should chime in soon with the answer for you. :bmw:
 

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The wearing away of your tire in some form of a repeatable pattern most often occurs on the front tire and most often on heavier bikes. It can and does happen on lighter weight bikes but not not as often. Oh yea back to the cause . . . It is the inability of the tire to remain in proper / constant contact with the road surface under the various riding conditions the bike is subject to.

So what are the root causes: tire pressure, tire compound, temperature, speed, weight on the bike, road conditions, balance of the tires and the condition / dynamics of the suspension system. Look at it this way - if the tire cannot travel and conform uniformly at all times on the road surface various portions of the tire get scrubbed more than others. The bottom line is the suspension systems inability to keep the tire in proper road contact.

The inability of the tire to rebound at high speeds - note most often is not the tires fault it is all the other issues imposed on the tire themselves that manifest in cupping the tire. Since you cannot alter most of the root causes mentoned the only chance you have to reduce or eliminate the problem is to change the suspension system (shocks and springs) or modify the tire pressure or both.

Closely monitoring the tire pressure is the only easy way minimize and possibly eliminate cupping. By raising and lowering the pressure you change the dynamics of the suspension system which will allow the tire to conform to the road under load and rotational forces and speeds. Problem is once it gets started almost always going to get worse even if you get the air pressure correct.

Most riders here set the Metzlers to 42 psi (f) and 48 psi (r) and live with the results. Others will chime in with different results but the root causes they operate under are most often different - single riders versus double riders and large riders.

That's my 25 cent answer to your 5 cent question . . . :D
 

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"The bottom line is the suspension systems inability to keep the tire in proper road contact."

I have to respectfully disagree. Most scalloping takes place in low speed turns on even, smooth pavement where the suspension is barely - if at all - active.

Spending more time in the arc of left hand turns versus right turns and the resulting additional "scrubbing" is the only reason, period.

Keeping up with tire pressures - along with braking before turns - can help to mitigate and delay scalloping, but it is virtually impossible to stop.

Unless... you are willing to ship your bike to England - and spend half of your seat time riding there. :D
 

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I'm with Mr. Miller on this one. We invest alot more time and distance in a left hand turn than the shorter radius right handers.
 

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Braking late and in the corners KILLS tire on the LT very quickly !!
 

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Suspect most apply a bit more throttle in a left hand turn (intersection type) rather than a tighter right hand turn. Would think that would add some scrub to the front tire. I know I do, but it's flat in KS and we have to take the lean where we can get it or we never wear out the sides of the tires.

jim h.
 

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Very interesting thread here..........good information and intelligent arguments......... :corn:
 

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jrh2020 said:
Suspect most apply a bit more throttle in a left hand turn (intersection type) rather than a tighter right hand turn. Would think that would add some scrub to the front tire. I know I do, but it's flat in KS and we have to take the lean where we can get it or we never wear out the sides of the tires.

jim h.
I agree, and there is no question I tend to ride high speed left hand sweepers much faster than right ones due to increased visibility. It all adds up...

I understand all the cafe racers in Kansas hang out at traffic circles. :D
 

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motorhead said:
Braking late and in the corners KILLS tire on the LT very quickly !!
Just a comment on braking in the corners.

During my career in the automotive industry, I was privileged to have personally received race track training from some of the best (including Jackie Stewart, but that's an entirely different story). I remember from one of my first training classes the instructor saying "tires are very stupid, they cannot multitask and can only do one job at a time. They can turn or they can brake, but they can't do both at the same time." He went on to describe in detail the physics behind the statement, which I won't get into. However, I still remember his words whenever I'm riding aggressively in the twisties and they haven't failed me yet :D
 

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Interesting info.

The variable I can control in all of this is tire pressure. It has become clear to me that if I do a better job of monitoring tire pressure and keep the front tire at 42 psi, my front tire lasts longer. Or, more correctly, it wears more evenly. When I slack off on watching the tire pressure the cupping/feathering/scalloping/whatever happens more quickly and is more pronounced.
 

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hschisler said:
Interesting info.

The variable I can control in all of this is tire pressure. It has become clear to me that if I do a better job of monitoring tire pressure and keep the front tire at 42 psi, my front tire lasts longer. Or, more correctly, it wears more evenly. When I slack off on watching the tire pressure the cupping/feathering/scalloping/whatever happens more quickly and is more pronounced.
+1
 

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RonKMiller said:
I understand all the cafe racers in Kansas hang out at traffic circles. :D
Sounds risky, there are about 3 traffic circles in the state that I can think of, most Kansan's don't know how to act with them.

jrh
 

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pickerbiker said:
Just a comment on braking in the corners.

During my career in the automotive industry, I was privileged to have personally received race track training from some of the best (including Jackie Stewart, but that's an entirely different story). I remember from one of my first training classes the instructor saying "tires are very stupid, they cannot multitask and can only do one job at a time. They can turn or they can brake, but they can't do both at the same time." He went on to describe in detail the physics behind the statement, which I won't get into. However, I still remember his words whenever I'm riding aggressively in the twisties and they haven't failed me yet :D
Well, if the instructor said or meant "maximum" braking or "maximum" turning, then I agree. However, at anything short of maximum effort braking or turning, a combination of both braking and turning is absolutely possible. The contact patch of the tire can provide a roughly fixed amount of horizontal force. The force vector can be rotated around the tire to point any direction. As the vector rotates around the tire, the tire can provide acceleration, deceleration, or side force either side (left or right turn) or an infinite number of combinations of turning and acceleration or deceleration.
 

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To my mind (which admittedly left the room many years ago ) that is an excellent description of trail braking. ;)

I've only had the opportunity to practice it a few times on a closed race course. It takes an amazing amount of skill to do it correctly. I never really "got it", but it was sure fun trying.
 

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Voyager said:
Well, if the instructor said or meant "maximum" braking or "maximum" turning, then I agree. However, at anything short of maximum effort braking or turning, a combination of both braking and turning is absolutely possible. The contact patch of the tire can provide a roughly fixed amount of horizontal force. The force vector can be rotated around the tire to point any direction. As the vector rotates around the tire, the tire can provide acceleration, deceleration, or side force either side (left or right turn) or an infinite number of combinations of turning and acceleration or deceleration.
Yes, the point he was making was maximum. The typical inexperienced rider will enter a curve too hot, miscalculate the apex, realize they're about to lose it, then try to correct their mistake by hitting the brakes when they're already leaned into the curve. This basically just compounds the problem as excessive use of the front brake can result in a loss of grip as the tire's adhesion is split between cornering and braking. The simple thought of braking, then turning helps sequence the process for non-professional riders.

Proper trail braking is done by racers to enter more deeply into the turn, but takes a lot of finesse to ensure they're off the front brakes as the bike lean angle becomes severe. At this point, they've also lost the braking advantage of load transfer onto the front tire. There are definite advantages to the street rider who can trail brake by seeing more of the curve and expanding the safety margin, but it's a very hard skill to perfect.
 

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pickerbiker said:
Yes, the point he was making was maximum. The typical inexperienced rider will enter a curve too hot, miscalculate the apex, realize they're about to lose it, then try to correct their mistake by hitting the brakes when they're already leaned into the curve. This basically just compounds the problem as excessive use of the front brake can result in a loss of grip as the tire's adhesion is split between cornering and braking. The simple thought of braking, then turning helps sequence the process for non-professional riders.

Proper trail braking is done by racers to enter more deeply into the turn, but takes a lot of finesse to ensure they're off the front brakes as the bike lean angle becomes severe. At this point, they've also lost the braking advantage of load transfer onto the front tire. There are definite advantages to the street rider who can trail brake by seeing more of the curve and expanding the safety margin, but it's a very hard skill to perfect.
I agree. It definitely simplifies things for the novice. However, I have also had people who didn't really understand the concepts get the impression that ANY use of the brakes while cornering would result in instant death. That is equally bad as few street riders use either maximum braking or maximum cornering, so there is almost always margin available to do both. And knowing this can be very useful.
 
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