Tire Capabilities and Limitations

[Darth Do'Urden]

So as a know-nothin' newb, I'm wondering how I go about learning the capabilities and (more importantly) the limitations of my particular tires. How do I determine this without hurting myself or my bike? And to simplify this discussion, let's assume perfect riding conditions (weather, rode, tread wear, etc.)

Is there a speed:lean ratio I should know about, or is all just about subjective "feel"? I always hear that the bike and pretty much by default the tires are more capable than I am (the rider in general, not just "me").

I'd just rather try to figure out how far and fast I can lean without having the tires slide out from under me.

For reference, I'm on Bridgestones BT-016 Front, and BT-023 Rear.

Someone be the Qui-Gon to my Obi-Wan. :vader:

[Nick_Ninja]

Wear out the Bridgestones and buy Michelin's to begin with.

[CaneZach]

You're asking for a simple answer to a question that requires much, MUCH more information, but I'll give it a try:

Think of lean angle as a mathematical equation, like X = Y multiplied by Z. Lean angle is a by-product of the speed you're traveling at and the radius of the line you take through a curve. The actual mathematical equation for lean angle is Lean Angle = inv. tan multiplied by (0.0668 x speed)/radius of the curved path. The higher the speed, the more lean angle you need to negotiate a curve. If you take a curve at 35 MPH and you have to lean the bike 24 degrees from vertical, you'll have to lean the bike about 61 degrees to negotiate it at 70 MPH. The tighter the curve, you'll see yourself having to lean the bike over further, even at lower speeds.

The bike can be leaned over until something solid touches the ground. The problem comes from A) is the rider able to achieve such a lean angle, and B) can the tires hold that angle. Normally, A comes into play far more than B does, unless you're talking about MotoGP level riders. The rider's inability to achieve those leans come about through a series of errors, mainly stemming from the "Oh crap, I'm going to crash!" sensation that causes people to do things like dynamite the brakes while they're leaning the bike over, which shifts too much weight onto the front tire and causes it to wash out. You also have target fixation, which means you're going to steer where you're looking. When you panic and you stare right at a tree, car, or guardrail, you're going to steer right into that tree, car, or guardrail. As the saying goes; Look where you want to go, not where you're going.

To understand the basics of cornering, you have to understand counter-steering first. Counter-steering means you initially push the bars in the direction OPPOSITE of the turn. To turn to the right, you steer to the left.

During the turn, you want to split the weight about 40/60 front to rear, so you add a little maintenance throttle to get the weight transfered until you've reached the apex of the curve. Then, you can add a bit more acceleration to stand the bike up as you exit the curve.

In short, your tires are more than likely able to sustain some decent lean angles, assuming they're in good condition. Your bike is more than capable of achieving a pretty steep lean. It's the rider that holds the bike back.



Hey, Jeff!

[Nick_Ninja]

:D Z

[SOCAL4LIFE!!]

Sell the Bridgestones and buy Michelin's to begin with.

Fix'd :)

[OUTLAWD]

For reference, I'm on Bridgestones BT-016 Front, and BT-023 Rear.




not sure what bike you are on, but it is generally a good practice to run the same model tires front and rear, they are designed to compliment eachother and work at the same lean angles.

Any reason you're running a sport front and sport touring rear?

I always try to determine limitations at the track, even IMI. you can progressively push harder and harder until you feel a tire slip, or some other issue becomes evident.

There is pretty much no empirical formula to tell you when it is going to slip, you have to figure that out for yourself. but you should have realistic expectations...wanting a touring tire to hold up on the track is just as realistic as expecting a race tire to last on a cross country road trip. Things will also vary bike to bike. My heavy sport touring triumph does not have the same lean angle available as my gixxer, so I have to ride them differently with that in mind. you can generally use your rear chicken strip as a reference for the lean angle left on your tires, but tire profile plays a role here as well, a touring tire is generally going to have a rounder profile, creating less of a contact patch at full lean, than a steeper, sportier tire that is designed to have an increased contact patch at full lean, and the bigger the contact patch, the more available grip you'll have...

like CZ said...you are asking for a simple answer to a question that I'm not even sure an answer exists...because even if something is physically possible, doesn't necessarily mean you would "feel" comfortable doing it

[tecknojoe]

Get some miles under your belt, then hit the track if you want to start to figure out limitations. One reason I cornerwork in between track days is because there is a LOT to be learned by watching the same turn all day. I would highly recommend spending some volunteer time at the track, you will pick up little trinkets of wisdom as the season goes along.

[brennahm]

Not sure if this was contained in CaneZach's novel, but...

...Keep in mind that if you (same rider) ride the same corner, same tires, same bike, same conditions but with different body position - you will have a different available combination of lean angle and speed.

[CYCLE_MONKEY]

Keep going faster and leaning farther over until you crash, then you'll have your answer! :)

(Kidding)

Honestly, the best thing, is practice, practice, practice. The important thing is to get a FEELING for what's happening with the tires, and the rest of the bike. FEEL when the tires are starting to move around. FEEL when the suspension is moving around. The best riders are so instinctive, that they just feel what's happening and their body reacts without conscious thought. The mind just projects a desired trajectory, and the body makes the bike follow that trajectory. These riders are rarely flustered even when there's a "pucker" moment (unexpected sand, pothole, etc.), they just react instantly and the moment is over in a split second with only a small deviation from the original trajectory. Seat time is your best friend, don't try and analyze it because there are way too many variables, just ride.

[rybo]

I'm going to put a different spin on this.


We live in an amazing age, an age where the performance of a $9000 sport bike with a $300 set of tires can rival the performance of a $100,000 sports car, provided that the rider is up to the task.

The motorcycle responds to the inputs we give it and in return it gives us feedback. Often times there are many streams of feedback for every input we give it. You twist the throttle and your greeted with the feedback of the bike moving faster, the engine sound changing pitch, the visual sensation that you're moving faster etc. So long as it's in good condition the bike responds PERFECTLY to the input we give it. Bad input = bad result, but again we live in an amazing age where the capability of the motorcycle can mask some of our (human) errors.

The limit of traction on a given set of tires has far MORE variables that most of us (me included) are capable of understanding. Tire companies employ many engineers in an effort to understand this exact question. I don't think that I could even get 50% of the way through the list of variables that determine the limit of traction that a motorcycle tire may have. What I do know is that the equipment I use (and I use a 14 year old motorcycle) is MORE capable than I am as a rider. How do I know this? Because I know riders who are more capable than me and if I lend them my bike they go faster around a racetrack on it than I can.

Simple answer to your question, with the tires you're using if you're getting to the limits of their traction on the street you're simply riding too hard on the street. There is no reason to approach that limit in that environment. The tires you are using are high quality tires and shouldn't have any problem keeping pace with you.

My .02

[Darth Do'Urden]

Original tires when I bought it were Bridgestone BT-016 f/r. The rear went bad after a long trip from Texas to Kansas and back, but the front still had plenty of life.

So when I went to get a new rear tire it was highly recommended to not mix brands, and to go with a sport-tourer for what I'd be doing (not track). It looks like the front will probably last about as long as the new rear, and I'll switch it to a sport-tourer at that time.

As for the practice...I'll be getting a lot more in now that I'm in an area that I can, which is really why this came up in the first place. I'm starting to get more comfortable with shifting my body weight off the bike more so than relying on counter-steer alone, but much less so in blind right turns (naturally)--it's those turns that I tend to go unintentionally wide and put myself in a potentially bad spot. But it's also those blind rights that I feel much less confident in the traction than I do with left turns.

This whole issue may really just be a matter of experience, and I'm ok with that answer. I'd just like to make sure that it really is just that, and that I'm not in danger of pushing the sport-touring rear beyond it's designed capabilities, which for my purposes is pretty much just canyon carving, as I'm not in a position to taker her to the track.

I'm certainly not wanting to push the limits on the road. I'm just trying to get a half-decent understanding of what those limits are. I'll never be a super-racer, and I'm not trying to be. But I do want to be the best I can be in my given environment without hurting myself.

If rybo's statement of the tires being of high quality and having no problem keeping up with me, then I'll just secure a mindset that the tires will stay put and I simply need to gain more experience and appropriate confidence in the tires themselves.

[Bueller]

I would get someone who knows what they are looking at to follow you for awhile and give you some feedback on your body position and riding technique and make sure you aren't effin a football. Once you get that straight the lean thing will come easier.

[Zach929rr]

Simple answer to your question, with the tires you're using if you're getting to the limits of their traction on the street you're simply riding too hard on the street. There is no reason to approach that limit in that environment.

This about sums it IMO. On the street you will run out of rider a look faster than you will run out of tire. The focus should really be on body position and smoothness of inputs as opposed to what $300 set of rubber is on your bike. That notion even applies out to the faster environments of the track. I used to run intermediate on 2CTs and never once thought that a set of race rubber would be my next "improvement" to make me a better rider.

[dragos13]

Not sure if this was contained in CaneZach's novel, but...

...Keep in mind that if you (same rider) ride the same corner, same tires, same bike, same conditions but with different body position - you will have a different available combination of lean angle and speed.

This is what I was going to say. Two people on the exact same bike will have different "lean angle" limits. The more upright or crossed up you are, the more you have to lean the bike in order to go around the same corner at the same speed as someone with better body position.

You won't find your bikes limits for a LONG time. You might find your own limits rather quickly, but I'm sure the bike will always have more.

[asp_125]

Under ideal conditions the tires will have more than you have on the street. Where things go wrong is when traction is compromised by rain, oil, sand, tar-snakes, etc. The feel for those traction limits is developed by seat time in all sorts of weather and conditions; sooner or later you will encounter them.

[Scer]

A lot has to do with just getting back to the basics. Make sure your bike is set up for YOU and not adjusting yourself to the bike. Its amazing how much of a difference you can get from just tuning your bikes geometery and suspension to fit you. If not, you are either gonna spend much more energy and/or money getting around the same stretch of road on a "detuned" bike rather than a tuned one. Thats because your suspension can put more stress on the tire than it needs to or you may have to more of an effort to lean the bike into a corner than necessary.

This sounds strange coming from a tire guy but its more important to have the bike work well first and then worry about the tires. The great part about that is you (usually) don't even have to buy new parts to tune the bike.

After that, then worry about tires. I can give you more insight about tires when it comes to that. The thing is that tires and rider and bike are so so dynamic. What works for one bike won't for another and what works for one rider doesn't for another. If I wanted to, I can take the best racer I have and put him on a tire/pressure combo that will land him on his ass in no time!! Its just what you do in a set amount of varibles that makes the best combo possible.

Not trying to make a shamelessplug but feel free to call me and I can explain this further. Kind of hard to write everything on a post from my phone. :)

learn on learnas

[tecknojoe]

BTW if it hasn't been said yet above, your tires are COLD when you first take the bike out of the garage. Never take an even remotely hard turn until you've been several miles to get some heat in the tires. Outside temperature plays a part in this as well.

I say because a lot of people get bit by forgetting their tires are cold right when they leave their house, even experienced riders forget

[Finklestein87]

Some really great info here!

[Vellos]

Sport-touring tires are fine, I've seen them keep up with my Power Pures on the street. Keep in mind that the street has debris and obstacles all over it, so you want to keep yourself at 70%. This means staying on the safer contact patch of your tires (not the edge) and leaving a good margin of error with speed and lean.

When you take the bike to the track you will forever understand the feel of your tires and their capabilities. If you've used up all of the tire, but are still not as fast as other people then you need to work on body positioning. The safest and usually fastest contact patch on a sport tire is not edge, you can knee-down far before that with keeping the bike more upright in the correct positioning.

[Penadam]

Sport-touring tires are fine, I've seen them keep up with my Power Pures on the street. Keep in mind that the street has debris and obstacles all over it, so you want to keep yourself at 70%. This means staying on the safer contact patch of your tires (not the edge) and leaving a good margin of error with speed and lean angle.

You talking about my sweet vfr tires? Pilot road 2 ftw!

[Vellos]

You talking about my sweet vfr tires? Pilot road 2 ftw!

Yeah. Like when we went up Left Hand with the two guys who fell behind and blamed it on their heavy bikes and sport-touring tires... when you had a heavier bike with the same tires as them. And less miles under your belt to boot!

[OUTLAWD]

I know more fast guys on touring bikes than I do on "sport" bikes ;)

[BC14]

I know more fast guys on touring bikes than I do on "sport" bikes ;)
I know at least 4........

[Bueller]

I know more fast guys on touring bikes than I do on "sport" bikes ;)

I know guys on Ninja 250's on bias ply tires that are quicker than a lot of sportbikes with the top of the line hyper sport tires around here :lol:

[Zach929rr]

I know more people that should ride cruisers instead of sport bikes than I do fast guys on "sport" bikes ;)

Fix'd

[asp_125]

This is the internet nobody's fast here, we just say we are. ;)

[Zach929rr]

I actually get off of my bike and rotate it on the kick stand mid-corner because I park it so hard.

[cptschlongenheimer]

BTW if it hasn't been said yet above, your tires are COLD when you first take the bike out of the garage. Never take an even remotely hard turn until you've been several miles to get some heat in the tires. Outside temperature plays a part in this as well.

I say because a lot of people get bit by forgetting their tires are cold right when they leave their house, even experienced riders forget

^
+1 This mistake almost resulted in a highside for me once. Scared the crap outta me... :eek:

Always warm em up before hard turns, hard braking & hard accelerating.

Huh, Huh... He said "Hard"...

[MetaLord 9]

BTW if it hasn't been said yet above, your tires are COLD when you first take the bike out of the garage. Never take an even remotely hard turn until you've been several miles to get some heat in the tires. Outside temperature plays a part in this as well.

I say because a lot of people get bit by forgetting their tires are cold right when they leave their house, even experienced riders forget
We're getting into cold tire season too. You go to dinner while it's still warm & the sun's up, but it sets & the temp drops by the time you get out and your tires are cold. I've seen plenty of friends drop it at low speeds due to cold tires and a little too much throttle.

[OUTLAWD]

I know guys on Ninja 250's on bias ply tires that are quicker than a lot of sportbikes with the top of the line hyper sport tires around here :lol:

I was passing 600's on my POS ninjette on stock rubber at HPR, but I was nervous the entire time that the dry tires were gonna let go and I was gonna take both of us out :lol:



This is the internet nobody's fast here, we just say we are. ;)

I'm slow

[rybo]

I say I'm fast, but it's not true. :yes:

[MetaLord 9]

Slow on the street, fast in the sack. wait...

[Zach929rr]

Slow on the street, fast in the sack. wait...

:o

[CYCLE_MONKEY]

Well, geez, could the Metezler M3's be considered "sport-touring" tires now?

[OUTLAWD]

no

[Penadam]

Yeah. Like when we went up Left Hand with the two guys who fell behind and blamed it on their heavy bikes and sport-touring tires... when you had a heavier bike with the same tires as them. And less miles under your belt to boot!

What killed me was they weren't even making excuses. It was Mr. GSXR 750. "I have 130 hp and the reason I'm behind you is because I'm trying to film. And stay closer to my friends. Also revving my engine at every stoplight makes me super cool."

[CYCLE_MONKEY]

no
Damn! There goes my excuse for being slow! I'll have to think up a new one........uhhh, my tire pressure wasn't right? I'm OOOOLLLDDD? I only got one good eye??? :)

[BC14]

Damn! There goes my excuse for being slow! I'll have to think up a new one........uhhh, my tire pressure wasn't right? I'm OOOOLLLDDD? I only got one good eye??? :)
So, ST tires make ya slow? Someone better tell my bike that :p

[CYCLE_MONKEY]

So, ST tires make ya slow? Someone better tell my bike that :p
Well, we just didn't want to hurt your feelings......you being a cop and all....... :)

[TinkerinWstuff]

Slow on the street, fast in the sack. wait...

http://seobullshit.com/wp-content/uploads/2010/06/Family_Vomit.jpg

[Darth Do'Urden]

Sorry to derail the derailing...you'll just have to forgive me =P.

So yesterday I learned for myself in a very practical way what was causing most (if not all) of my lack of confidence in the tires: body position/posture.

Thanks to boards like this, I had acquired the head knowledge of what I was supposed to be doing with my body, but had yet to put much of it into practice. But yesterday, over the course of 240 miles, I started to gradually play with shifting more of my body off the seat of the bike, while getting my upper body low enough on the bike to have my arms parallel to the ground (and also keeping them loose and relaxed). What I quickly discovered was that proper positioning is SO MUCH more comfortable and confident than improper positioning. What I thought was going to feel sketchy (shifting more of my body weight off the seat) felt amazing "right".

After riding in the correct position through turns for a while, I immediately felt the discomfort and total lack of confidence when I failed to set up for a turn properly, resulting in body-stiffening, which in turn prevented me from being able to get the bike to turn as tight as I needed (due to tightened arms and an outside leg that wasn't pushing), which of course meant running wide of my intended track through the turn.

I realize all of this likely elementary to a lot of you at this point, but I thought I'd share for those that are at the same point in their education and experience as I am. It's pretty awesome to go from a head knowledge to actually "feeling" what's right compared to what was so very wrong in retrospect.

When setting up properly and being in the right position, not once yesterday did I have that feeling of the tires giving way. Granted, some part of that was from a physics standpoint I literally didn't have to lean the bike as far, but even when a tight lean was necessary I didn't get nervous...I just leaned it a bit further, the tires themselves being the furthest worry from my mind.

It was an epiphany, so I thought I'd share. =)

[Vellos]

You have a lot more tire angle before you need to lean off, but practicing body positioning is good (I still need a lot of work in that department). If your tires feel like they're slipping your psi might be too high or you're riding on some sand. As I suggested before, go to IMI and you'll vastly improve street riding, send me a PM if you want to know when I'll be going next.

[Darth Do'Urden]

You have a lot more tire angle before you need to lean off, but practicing body positioning is good (I still need a lot of work in that department). If your tires feel like they're slipping your psi might be too high or you're riding on some sand. As I suggested before, go to IMI and you'll vastly improve street riding, send me a PM if you want to know when I'll be going next.

Yeah, I totally get that leaning off isn't exactly "necessary", but the proper positioning is not only "proper" in the technical sense, but like you mentioned, it's good practice.

The discomfort level never came from actually feeling the tires slipping, but just from that great "unknown". Practicing the proper positioning definitely help to alleviate this feeling of uneasiness and put to rest the fear that the tires might slip, even at moderate speeds in the twisties.

IMI sounds like a great idea...except for the cost =). Not something I have room in the budget for right now.

[brennahm]

IMI=$35

?

[Darth Do'Urden]

IMI=$35

?

While that's reasonable, there's not $35 just sitting around unallocated in my family's budget. Sure there's extra money every month, but there's other pressing needs that need saving for more than me doing IMI.

In due time....