Killboy - NOT!!!! But we did try some Ridin' Pics

[Joe Frickin' Friday]

And Mitch...if you find any problems with the formula, contact the guys I plagiarized from :

http://www.physicsforums.com/showthread.php?t=221863

 

Who knows, I might have been the original author...

[TyTass]

That looks a lot like my Physics III final from college, somewhere back in the Middle Ages of 1980 - back when I was trying to obtain a BSEE (and quit!).

 

But Hey, Silly, I was not saying that proving the physics behind turns on a motorcycle was easy! I know you were probably just givin' me a load of it but you do know you went and scared everyone again into thinking we non-physics kind 'o-people can't understand physics!

 

What I was referring to is best displayed by Hough's graphic:

[StretchMark]

Yep, just giving you a hard time.

I like the Hough picture too. I think it is very similar to what we will see in the promised pictures.

[Albert]

I think I spotted a parenthises out of place. It was a minor formula though.

 

Hi Mark.

[Firefight911]

I think I spotted a parenthises out of place. It was a minor formula though.

 

Hi Mark.

 

Anybody get a haircut lately!?

[TyTass]

I think I spotted a parenthises out of place. It was a minor formula though.

 

Hi Mark.

 

Anybody get a haircut lately!?

Does shaving one's head count?

[lawnchairboy]

looks like my before and after video from ridesmart when you chased me mark.

 

it was stunning to see the difference...

 

chris

[GregB]

As I read the formula that you presented, it seems designed to calculate the change in effort required to TURN (as in steer) the wheel as you change the weight of the front wheel assembly.

Remotely connected to a motorcycle going around a corner but not really relevant unless you are trying to decide if it is worth going to ultra light wheels on your racing motorcycle.

[russell_bynum]

As I read the formula that you presented, it seems designed to calculate the change in effort required to TURN (as in steer) the wheel as you change the weight of the front wheel assembly.

Remotely connected to a motorcycle going around a corner but not really relevant unless you are trying to decide if it is worth going to ultra light wheels on your racing motorcycle.

 

So....that would mean that Mark said something silly and irrelevant????? I guess there's a first time for everything.

 

 

[motorman587]

 

I'm not really trying to get into a Ride Well discussion here...I was trying to respond to John's martyr post about how we all gang up on him because he has other ideas.

 

But...all of the stuff you said is a perfect example of what I was trying to explain to John. You gave some reasons why you do it the way you do it and some reasons the way we're talking about might not be the best. From there, a good discussion can develop and everyone has an opportunity to learn. That's not what John does in these discussions.

 

 

Is this not discussions right here.............

Motor school and MSF are not all about slow speed. There are two ways to steer a motorcycle. Low speeds, which is turning the steering wheel, which you can counter balance, if needed or at speed, which is above about 10-12 mph then you need to counter-steer. Again these are techniques. We at motor school have about 1/2 track with a couple of turns where we practice that.

 

and here is another.............

To me this looks as if the entry speed was to hot. More lean angle was due to the speed not because you where kissing the mirrors. Also if you kept your head level this would've helped too. Slow, look, lean, and roll..........

[motorman587]

My points are that there are more than one way to attack a curve.

 

For about the six hundred millionth time......

 

 

Yes...there are many ways to do things.

 

The purpose of this forum is to allow riders to discuss various techniques and strategies. You have never once said anything like:

The advantages of sitting upright in a corner are: X, Y, Z.

 

or

 

The disadvantages of the "kiss the mirrors" body position are: X, Y, Z.

 

or better yet:

 

Yes...you do minimize lean angle in the corner with the "kiss the mirrors" technique, but the downsides are X, Y, Z, and IMO those outweigh the benefits.

 

 

Instead you just keep saying That's how I do it. Or There's more than one way to attack a corner. Or you cite your experience and training. None of that contributes to discussion. I don't care that you've got a bunch of awards for police rodeos or that you've been teaching for a long time...if you can't (or won't) discuss the how and why of what you're teaching, it's just noise.

 

When I ask Keith Code why he's teaching one thing while someone else (someone with more success as a racer, even) is teaching something different, he explains why they teach what they teach, and the pros and cons of the "other methods". Sometimes he'll take me out and put me on the bike and show me first-hand. That's worthwhile discussion. What you're doing is preaching your dogma and there's really no place for that in this forum.

 

 

I was "not" trying to compare the too, but point and I guess you missed that too, was when you commented with............................

This is a classic mistake. Bullet's upper body position (kiss the mirrors) is looking good at first. Then, as she gets into the turn and the bike leans, she sits back upright. Her mind is seeing the ground getting closer and saying "There be dragons there...don't go down there." Of course...the whole point of the "kiss the mirrors" thing is minimizing lean angle to increase traction and therefore make it less likely that you'll have a run-in with any of the pavement-dwelling dragons. Sitting upright is totally counterproductive...it's a survival reaction, and though is may be appropriate in the context of eons of human evolution, it is not appropriate in the context of riding a motorcycle.

 

I understand that "kissing the mirrors" you have more lean angle in the curve, but if you do your set up correctly with the proper entry speed than you should not run out of lean angle. Are you attempting to go fast in the curve or are attempting to complete the curve smooth and safe?

 

Sometimes he'll take me out and put me on the bike and show me first-hand.

Come to our school and I will show you too. We even teach a mini police motor school a day long. http://www.floridasaferider.com/index.cfm?pageid=20

 

When I read or if somebody is teaching me something I want to know what backing do they have in teaching me this. I want a bio, credentials on subject matter.

 

What are your credentials??? You are a good writer/typer but what makes you an expert on the subject matter.?????????

[russell_bynum]

I merged John's post (above) from the Ride Tales forum back into this thread so we can continue our discussion.

[russell_bynum]

Is this not discussions right here.............

Motor school and MSF are not all about slow speed. There are two ways to steer a motorcycle. Low speeds, which is turning the steering wheel, which you can counter balance, if needed or at speed, which is above about 10-12 mph then you need to counter-steer. Again these are techniques. We at motor school have about 1/2 track with a couple of turns where we practice that.

 

That's a discussion, but it isn't relevant. We're talking about body position, and you appear to be talking about countersteering vs. not countersteering. Correct? If I'm misunderstanding, please let me know.

 

 

and here is another.............

To me this looks as if the entry speed was to hot. More lean angle was due to the speed not because you where kissing the mirrors. Also if you kept your head level this would've helped too. Slow, look, lean, and roll..........

 

We already responded to this. Yes...slower entry speed would give you less lean angle. But..."Kiss the mirrors" body position will give you less lean angle for the same speed and line. i.e. It gives you more margin, and that's the case regardless of the other two variables. The best choice is, of course, to do all three....slow your entry speed, pick a good line, AND use your body position to reduce lean angle. All three of those things are tools that you can use to improve your margin.

 

 

[motorman587]

So I do discuss, but it is not relevant.........

 

That's a discussion, but it isn't relevant. We're talking about body position, and you appear to be talking about countersteering vs. not countersteering. Correct? If I'm misunderstanding, please let me know.

 

I understand that we already responded to this but my points were that you stated here that I do not discuss but preach...............

Instead you just keep saying That's how I do it. Or There's more than one way to attack a corner. Or you cite your experience and training. None of that contributes to discussion. I don't care that you've got a bunch of awards for police rodeos or that you've been teaching for a long time...if you can't (or won't) discuss the how and why of what you're teaching, it's just noise.

but below isn't that a discussion????????

 

We already responded to this. Yes...slower entry speed would give you less lean angle. But..."Kiss the mirrors" body position will give you less lean angle for the same speed and line. i.e. It gives you more margin, and that's the case regardless of the other two variables. The best choice is, of course, to do all three....slow your entry speed, pick a good line, AND use your body position to reduce lean angle. All three of those things are tools that you can use to improve your margin.

 

And where did rodeos come from?????????

[russell_bynum]

I was "not" trying to compare the too, but point and I guess you missed that too, was when you commented with............................

This is a classic mistake. Bullet's upper body position (kiss the mirrors) is looking good at first. Then, as she gets into the turn and the bike leans, she sits back upright. Her mind is seeing the ground getting closer and saying "There be dragons there...don't go down there." Of course...the whole point of the "kiss the mirrors" thing is minimizing lean angle to increase traction and therefore make it less likely that you'll have a run-in with any of the pavement-dwelling dragons. Sitting upright is totally counterproductive...it's a survival reaction, and though is may be appropriate in the context of eons of human evolution, it is not appropriate in the context of riding a motorcycle.

 

I understand that "kissing the mirrors" you have more lean angle in the curve, but if you do your set up correctly with the proper entry speed than you should not run out of lean angle. Are you attempting to go fast in the curve or are attempting to complete the curve smooth and safe?

 

Why do you seem so opposed to maximizing your options?

 

Sure....if you set the turn up correctly (good line, good entry speed), you can sit pretty much anyway to damn well please and you'll make it through the turn. But....since you can use your upper body to minimize lean angle, why would you not do it?

 

If you knew you were about to get shot at, would you just put on your kevlar vest, or would you want to have your vest on and be crouched behind an armored, bullet-proof door?

 

There are three components that we're dealing with here: Line, speed, and body position...you can optimize any or all of those to decrease the amount of lean angle you need to get through a turn. You only seem to be interested in talking about line and speed. Why are you ignoring body position?

 

 

Come to our school and I will show you too. We even teach a mini police motor school a day long. http://www.floridasaferider.com/index.cfm?pageid=20

 

That sounds like a great way to spend the day building skills. if I'm ever in Florida I'll give you a ring.

 

When I read or if somebody is teaching me something I want to know what backing do they have in teaching me this. I want a bio, credentials on subject matter.

 

What are your credentials??? You are a good writer/typer but what makes you an expert on the subject matter.?????????

 

I'm not an expert on the subject matter...not at all. I have studied it a bit...probably more than the average rider. I've spent a fair amount of time and money on training and practice. Most of that has been track-oriented and I understand that not everything from the track is directly applicable to the street. Likewise, I've spent a bit of time and money on improving my dirt bike skills. Some of the stuff there transfers to the street and some doesn't.

 

 

But...just because someone doesn't have impressive credentials doesn't mean they don't have anything meaningful or helpful to share. The whole purpose of this Ride Well forum is to allow anyone from David Hough and Keith Code to the guy who just bought his first bike yesterday to discuss riding techniques openly. Who knows...maybe the new guy has figured something out that nobody else has. Or maybe their fresh mind is seeing things more clearly than the people who've been around a long time. Or...maybe they just have a way of explaining something that clicks for someone else where all of the experts have fallen short.

 

And...just because someone's got great credentials, that doesn't mean their word should be taken as fact without question. I don't like to take anything just on someone's word alone....I want to know the how and the why. If an instructor can't (or won't) talk about the how and why behind what they're saying, alarm bells start going off in my head.

 

 

[motorman587]

I merged John's post (above) from the Ride Tales forum back into this thread so we can continue our discussion.

 

The post below are response to the quote below.

I'm not really trying to get into a Ride Well discussion here...I was trying to respond to John's martyr post about how we all gang up on him because he has other ideas.

 

But...all of the stuff you said is a perfect example of what I was trying to explain to John. You gave some reasons why you do it the way you do it and some reasons the way we're talking about might not be the best. From there, a good discussion can develop and everyone has an opportunity to learn. That's not what John does in these discussions.

 

 

[motorman587]

Why do you seem so opposed to maximizing your options?

 

Sure....if you set the turn up correctly (good line, good entry speed), you can sit pretty much anyway to damn well please and you'll make it through the turn. But....since you can use your upper body to minimize lean angle, why would you not do it?

 

If you knew you were about to get shot at, would you just put on your kevlar vest, or would you want to have your vest on and be crouched behind an armored, bullet-proof door?

 

There are three components that we're dealing with here: Line, speed, and body position...you can optimize any or all of those to decrease the amount of lean angle you need to get through a turn. You only seem to be interested in talking about line and speed. Why are you ignoring body position?

 

No, I am also interested in line, speed and body position, other things can happen in a curve. With sitting up straight that is one less thing I have to think about, ie kissing the mirror/ leaning over. What happens if I need to make an emergency stop in a curve and I am leaned off the motorcycle?? One I will have to sit up straight which will effect the COG before, second I will have straighten the handlebars. If I sitting up straight all I have to worry about is straighting the handlebars, looking straight and appling the brakes. Also are going to ride like this with a passenger??? No, you go back to sitting up straight.

 

Sometimes I felt that person/s on this forum attempt to teach/preach on how "fast" you can go through the curve. I understand your method, but what my point is if you approach the curve with proper "entry" speed, then maxing out the lean angle will not be a problem.

 

My whole point on this is sitting up straight can be a safe method too, if done correctly. Just as wearing a vest does not mean I can run into a gun battle.......I need to use duck and run method.

[russell_bynum]

So I do discuss, but it is not relevant.........

 

 

LOL! Sorry John...I didn't mean it that way.

 

I meant that particular discussion didn't seem relevant. Like I said...we were talking about body position to minimize lean angle, and you came in talking about countersteering vs. not. It's apples vs. oranges.

 

 

And where did rodeos come from?????????

 

My memory was that you've won a bunch of awards for your riding skill at motor officer competitions...which I thought were called police rodeos. The point was I was saying that I know you are a tremendously skilled rider and I wish we could be more effective at communicating here so we could learn from your experience and skills.

[russell_bynum]

No, I am also interested in line, speed and body position, other things can happen in a curve. With sitting up straight that is one less thing I have to think about, ie kissing the mirror/ leaning over. What happens if I need to make an emergency stop in a curve and I am leaned off the motorcycle?? One I will have to sit up straight which will effect the COG before, second I will have straighten the handlebars. If I sitting up straight all I have to worry about is straighting the handlebars, looking straight and appling the brakes.

 

 

YES!!!!!!!!!!!!!

 

This is exactly what we've been trying to get out of you. This is good stuff that we can talk about.

 

Definitely, doing anything "unnatural" with your body means you just have one more thing to think about. Personally, I've found that I had to really think about it for a while, and now I'm at the point where I do it half-assed if I don't think about it at all, and it requires minimal thought to do it well. I assume that eventually I could get to the point where I didn't have to think about it and it would just happen, but I don't know.

 

Braking...if you don't need really hard braking, there's no reason not to just stay in cornering position with the bike leaned while you brake. If you need to really stop the bike RIGHT NOW, then yeah...you've got to stand it up first and the farther out of "braking position" you are, the worse off you are going to be.

 

That's where "kiss the mirrors" is a compromise. The best body position for minimizing lean angle is hanging off like the racers do. The downsides are that it's difficult to learn to do it well, it's much harder to change direction since you've got to drag yourself up across the bike (without disturbing anything), etc. "Kiss the mirrors" is a compromise. You keep your lower body anchored in place so it's much easier to move around. It's also easy to learn...most people can master it in less than an hour. Definitely, you have good points about that, though. IMO, the benefits outweigh the drawbacks (usually), but that's just me.

 

Also are going to ride like this with a passenger??? No, you go back to sitting up straight.

 

Why? I definitely ride like that with a passenger. If it's a passenger I know and trust, I'll ask them to do it, too. I know, for example, that Ken and Donna ride that way (somewhere there's a picture from when they did RideSmart 2-up) and Mark and Sylva ride like that too...in fact she's usually moving around more than he is.

 

 

Sometimes I felt that person/s on this forum attempt to teach/preach on how "fast" you can go through the curve. I understand your method, but what my point is if you approach the curve with proper "entry" speed, then maxing out the lean angle will not be a problem.

 

That certainly has never been my aim. Most of us (and definitely myself) go too fast through the corners anyway. Most of my training has focused on giving myself bigger margins. At the track, I use that margin to lower my laptimes (i.e. increase speed), but on the street, I use it to increase margins. Mostly my goal when riding the twisties is "Smooth", not "fast".

 

My whole point on this is sitting up straight can be a safe method too, if done correctly. Just as wearing a vest does not mean I can run into a gun battle.......I need to use duck and run method.

 

Right....but if you're crouched behind the armored door and someone sneaks up and starts shooting at you from behind, you'll be glad you have that vest on.

[Whip]

I wanted to add a couple pix from a very very good off road rider on a race track. The 950 ADV can be ridin this way because it's very narrow and has a lot of ground clearance. If he's tryin to "dirt track it" or slide the rear SM style he's doin a good job, but I think, he thinks he doin it the right way????????.....I could be wrong.....I don't wanna insult the man, because I respect his off road knowledge and I hope to meet him some day.

 

 

 

 

Whip

 

 

[russell_bynum]

I've got pictures of a guy riding an R1200GS like that at Streets of Willow...just before he levered the rear off the ground with the crash bars and lowsided.

 

The whole supermoto style is something that I really don't understand. I've tried it on my DRZ and it is insanely fun, but I don't understand the mechanics of why you ride that way. But....supermoto bikes generally don't have ground clearance issues. I guess you don't have to worry about ground clearance when the first thing that touches is your bar ends.

 

 

Here's Lisa cross-controlling some wicked lean angle into the CBR.

 

 

Here she is in the same corner, 15 seconds a lap faster. Body position still needs work, but what she's doing is already making a big lean angle difference.

 

[Ken H.]

Kind of late to this discussion, but I’ll through a couple of thoughts out...

 

First regarding CofG in a given turn. The CofG location is determined by a combination of all of the mass going around the turn. Bike and rider(s). If the rider is leaned inside (using k.t.m.) and the bike is leaned xx degrees, or if the rider is upright and the bike is leaned xx + degrees, the calculated total CofG location is the same. It’s not germane to the specific discussion.

 

What is germane, important, is how much traction the tire has with the road to keep us on it. And other factors like how well the bike’s suspension can work with gravity to do the same thing when it is more upright – to keep us from crashing.

 

Few can credibly argue that an leaned bike has better traction than a upright one. And by extension, a more leaned bike has better traction than a less leaned one. That is not the case has been proven over and over again. If such were so, a leaned bikes would never fall over in a curve only upright ones would! If someone doesn’t believe that basic fact of how a motorcycle works, a learning discussion can probably go no further.

 

So the above leads to one inescapable goal – to maximize my available traction, to maximize the bikes ability to stay on the road and keep me safe, I need to lean it less.

 

There are a lot of ways to do so, one of which is of course slow down, but one absolute way to ride a bike with less lean for a given speed is to move your body inward. The portion of the location of the CofG required to maintain a given desired/arc through a curve that is contributed to by the bike’s mass is less, because your body’s contribution is more when your body mass is inside the bike’s centerline, that when it is in alignment with it (sit upright style).

 

Does it matter? No. Not that is until you need more traction to survive a turn than the bike can deliver at that moment for the way it is being ridden at that moment. Then it matters more than anything in the world.

 

It boils down to a very simple formula... Less bike lean = more bike traction. More traction is good, less is bad.

 

I have a friend (if he reads this he’ll recognize the reference) who does almost everything wrong of RidingSmart, k.t.m. But yet he is very fast. I’ve said to him, “You’re living only on the ability of your tires to overcome your riding style.” (Interestingly he agrees, but that’s another discussion about his regard for his own life.) Why doesn’t he crash? Not because his technique is superior, but because he hasn’t (yet!) discovered the limits of his tires. His tires (like most today) are able to keep traction for the technique he is using. He (to pull some numbers out of the hat) is riding using 80% of their available traction, where as a k.t.m. rider in the exact same ride is using only 70% of the tyre’s total available traction. But neither rider crashes because neither rider ran out of traction. For both of them their margin of safety is still ‘good to go.’

 

Which is what RidingSmart, k.t.m., Code and a host of others who teach getting your body inside are really bottom-line all about - reducing your riding in a given situation from using 80% of the available traction to using 70% of it. (Or whatever number, less at any rate.) Thus increasing your margin, your additional available traction, should you unexpectedly need it.

 

Because, and it’s a BIG BECAUSE, should the unexpected arise and suddenly you need 25% more traction to stay alive for awhile longer, it’s much better to already be consuming only 70% of the total available than 80% of it.

 

Can a k.t.m. rider and a sit up straight rider both be safe? Sure. But the safety margin, as contributed to by bike traction (ignoring lines and all the other safety subjects for now) is, indeed by physics must be, greater for the k.t.m. rider than for the sit up straight rider.

 

In the end the discussion is all about traction margin / reserve. Which rider is closer to the potential catastrophic end of the ride, the k.t.m. rider or the straight up one?

 

[yabadabapal]

Im a bit nervous about entering this thread, but I have to ask a few questions. After spending 4 hours reading and examining all the posts including the numerical sentences representing physics, Ive come to a few conclusions composed of and integrated with all the information expressed. In other words, none of what I wrote are my ideas. It is just my attempt to incorporate all of your ideas together.

Surprisingly, a number of opinions that were in misunderstanding of each other, appear to me, to be both right, and both wrong, or more accurately correct at the appropriate time, and incorrect at the inappropriate time. All of it educational, professional and useful..Here is what I cam up with after reading and learning so much from all of you. I apologize for extending this thread further.

1. Kissing the mirror to reduce the lean as a means of increasing the amount of traction being used while saving the most amount of traction for any unanticipated incident is a great way to stay alive. Even in mathematics, this riding formula represents the only mathematical equation where the sum is inarguably + Positive. Its almost Zen like, because while your reducing the lean to save the most amount of unused traction, your also using the most amount of traction or tire, at the same time. Less lean, more tire on the road. More lean, less tire on the road.

2. Sitting straight is an absolute must in any situation where you must constantly be surveying a variety of traffic situations that are within immediate visibility and of concern, while at a speed that under any degree of counter steering is not going to exceed a lean that is not reversible and opposable and at a speed where constantly slowing or breaking and accelerating , is equally or more demanding than any other riding formula.

3. Now its getting interesting and I really am excited.

Can we incorporate both formulas at the appropriate time.

Example: Gong down the road at 60MPH on a sweeper, suddenly a cow appears 50 yards down the road. I was KTM but now I pull back and sit up straight so I can see all my options, and apply the brakes. Moving slowly within 20 feet of the cow, he charges me, head on. I go into an accelerated KTM, to the right and he just misses me as I see him fade away in my rear view mirror.Soon thereafter and far enough away from each other, both the cow and I relieve ourselves. (humor in the last sentence).

Seriously though, With all the great information all of you have shared, I want to incorporate and compose my theory of riding that is inclusive of all your styles but only in its appropriate and most relative situation in using that style. That way I can handle a variety of situations while enjoying all the great techniques that make riding more fun and safe. I know the cow story didn't quite make it, but does the rest of it seem to make sense.

 

 

 

 

 

 

[russell_bynum]

Less lean, more tire on the road. More lean, less tire on the road.

 

Do we know that this is the case?

 

Obviously...once you lean the bike to the point where the edge of the contact patch reaches the edge of the tire, any additional lean will result in a smaller contact patch.

 

But...I've read/heard conflicting reports about what happens before that point. Some folks say that the profile of the tire is such that the contact patch is actually smaller when the bike is upright than when it's leaned. The manufacturers do it that way on purpose because they know you need more traction when the bike is leaned. Also, a narrower contact patch when the bike is upright, would make the bike transition to a lean faster.

 

I've never taken the time to actually test this theory, but it makes sense to me at some level.

[motorman587]

Finally................

 

YES!!!!!!!!!!!!!

 

This is exactly what we've been trying to get out of you. This is good stuff that we can talk about.

[tallman]

Russell,

You're not alone in thinking there may be some merit to that concept.

Might depend on tire/profile, but I can see the concept being possible.

 

 

[Joe Frickin' Friday]

Some folks say that the profile of the tire is such that the contact patch is actually smaller when the bike is upright than when it's leaned. The manufacturers do it that way on purpose because they know you need more traction when the bike is leaned. Also, a narrower contact patch when the bike is upright, would make the bike transition to a lean faster.

 

(for StretchMark )

The fundamental physics model of dry friction says that the size of the contact patch is irrelevant; the model only accounts for normal (perpendicular) force and the coefficient of friction between the two materials (in this case, rubber and road).

 

If you want more friction (traction), you need a softer compound tire. If you want those soft compound tires to survive more than a lap or two, you need a large contact patch to reduce squirming/heat production. So it's not the large contact patch that confers greater traction, it's the soft rubber.

 

On those rare occasions (e.g. at cycle expos/shows) when I've been up close to a race bike on display, from what I remember the tire profile is almost a "V" shape: while rocketing down the straight, the contact patch is probably only a couple inches wide, but when they go to full lean, there's a massive amount of rubber in contact with the road.

 

I don't believe that this strange tire profile would be helpful unless they were using multi-compound tires, with hard stuff in the middle (to handle the high speed straights without melting/shedding), and soft stuff toward the edges (to take advantage of that massive contact patch when they're leaned way over).

 

We OTR riders want our tires to last more than a few hundred miles, so we're stuck with tires that have less of a "V" profile, something more rounded, giving a somewhat larger contact patch (compared to a race bike) during straight-line cruising - which means we end up with not such a giant contact patch during full lean. That means a reduction in the permissible disparity between tread compounds that may be used on the centerline and near the edges - if the manufacturer has chosen to make a multi-compound tire at all.

 

All a very long roundabout way of saying that if your tires are single-compound, the size of the contact patch isn't going to make much difference in available dry traction - and if they're multi-compound, they may in fact offer slightly improved traction at greater lean angles.

 

But the tires can't do much good if they're not kept in firm contact with the road: if your bike is heeled over 45 degrees, the suspension is going to have a real hard time doing its job. And that's what the RidingSmart position does for traction: get the bike closer to vertical so the suspension can help keep the tires against the road.

[Mike]

The fundamental physics model of dry friction says that the size of the contact patch is irrelevant; the model only accounts for normal (perpendicular) force and the coefficient of friction between the two materials (in this case, rubber and road).

 

Mitch--

 

This is something I've heard before, but, acknowledging that you have all the scientific knowledge that I lack, I don't get it. It seems counterintuitive. If this were the case, it would seem that there would be no disadvantage to retrofitting an RT with bicycle tires (assuming that they could handle the weight load).

 

This is pretty unscientific, but when I sit at my desk and press against it with the tip of my index finger, it doesn't take a lot of force to move it laterally. When I do the same with my palm pressed against the desk, it seems to require a lot more force. In my feeble mind, that seems to indicate that the greater contact patch of my palm creates greater resistance to lateral movement, which I attribute to friction.

 

Can you explain this in terms that a simpleton like me can understand? I just don't get it.

[Joe Frickin' Friday]

This is something I've heard before, but, acknowledging that you have all the scientific knowledge that I lack, I don't get it. It seems counterintuitive. If this were the case, it would seem that there would be no disadvantage to retrofitting an RT with bicycle tires (assuming that they could handle the weight load).

 

To get those skinny tires to handle the weight of the RT, you'd need a pretty hard compound - and that's when you start to lose traction. If you try to use a soft compound on a such a small contact patch, you end up with too much heat generated in the tire, and it'll destroy itself.

 

If you watch a formula one race where then get into rain, they trade in their "ordinary" slick tires for some really soft compound tires (with a tread pattern). This only works because the rain keeps the tires cool. When the track is spotty - some wet, some dry - you'll see them deliberately aiming for the wet patches to try to cool their rain tires down, cuz that soft compound gets smokin' hot when they run it in the dry. When they can't find enough of those wet patches, the tires get hot and can even start shedding tread blocks; ideally they pit around this time to go back to the dry-running slicks with the harder-but-still-ridiculously-soft-from-a-street-rider's-perspective compound.

 

This is pretty unscientific, but when I sit at my desk and press against it with the tip of my index finger, it doesn't take a lot of force to move it laterally. When I do the same with my palm pressed against the desk, it seems to require a lot more force. In my feeble mind, that seems to indicate that the greater contact patch of my palm creates greater resistance to lateral movement, which I attribute to friction.

 

I'll admit that real friction is a bit more complex than I let on in my previous post. Adhesives, for example, don't follow that simple friction model very well. But to a first approximation, i.e. for typical stuff lying around on your desk, that basic model - friction force equals normal force times coefficient of friction - serves pretty well.

 

In your experiment, we need to remove some subjective bias. Try this:

Find a five-pound-capacity postage scale. With your eyes closed, press on the scale with a fingertip, then with a palm, trying to apply the same force in both cases. Have an assistant read the scale (silently) each time; I'll wager you are applying a lot more force with your palm than with your fingertip.

 

After that, open your eyes, and repeat your friction test while actually applying the same normal force (as indicated by the scale) with your fingertip and your palm, and see what you get.

[yabadabapal]

Hey Mitch, great stuff. I want to ask you so I can better understand.

So in an exaggerated lean, its the soft material on the outer side of the tire that grabs and hopefully holds the traction, while the suspension is now somewhat asleep and not fully functioning.

But in a lesser lean (ridesmart) both the tire and the suspension are working in greater capacities together, sort of like sharing the responsibility, and more insurance for the rider.

But in a straight away, we are using the harder part of the compound, and least amount of tire and traction, but compensating for that is the greatest degree of using our suspension.

So Im thinking that my goal would be to ride in any situation in a way that allows all the relative pieces to share as much as possible an equal responsibility, offering as safe of a ride as possible. Am I on the right track with this.

[amz]

Here's a good article on this as well: Article.

 

And about 'body steering'

 

 

 

Attached a neat little tool I found somewhere on the net... A Windows Excel 'lean angle calculator'

3883.zip

[russell_bynum]

(for StretchMark )

The fundamental physics model of dry friction says that the size of the contact patch is irrelevant; the model only accounts for normal (perpendicular) force and the coefficient of friction between the two materials (in this case, rubber and road).

 

I remember that from High School Physics. Static friction is calculated by the mas of the object its coefficient of friction...no mention of the surface area.

 

I remember testing it with a bit of 2x4 and a scale...applying more force to the scale until the wood started to move. Then turn the wood so it's sitting on the 1.5" side instead of the 3.5" side and try again....it started sliding at the same force.

 

I can't help but think there's more to this than that, but maybe not.

 

Based on what you're saying...the only advantage of a bigger contact patch is it allows you to use a softer compound (higher coefficient of friction) for better grip, without giving up longevity. Right?

[Joe Frickin' Friday]

I can't help but think there's more to this than that, but maybe not.

 

That basic law is a very good approximation for most materials, but not all. Start throwing adhesives into the situation, or racing-compound tires that turn into something like rubber cement when you warm them up, and the rules may be a bit different.

 

Based on what you're saying...the only advantage of a bigger contact patch is it allows you to use a softer compound (higher coefficient of friction) for better grip, without giving up longevity. Right?

 

I suspect a larger contact patch may also make the tire more resistant to slipping due to running over small objects, like a handful of gravel, since you're more likely to have a useful percentage of contact patch maintaining good contact with the road. But in the absence of any authoritative comments from a tire engineer, I'm inclined to think this is a very minor factor (if at all) in tire design, and that yes, the primary reason for designing in a large contact patch is to enable the use of soft, grippy compounds.

 

The last few paragraphs of the article amz linked to (link again here) say pretty much the same thing.

[BeniciaRT_GT]

Don't forget you get more grip by applying more weight, which is also a factor when leaned over X degrees. Centripetal force adds "fake" weight to the tire, giving it more traction. As you reach 45 you start asking for more than 1G to keep the same constant radius.

 

Does that sound right?

[Joe Frickin' Friday]

Hey Mitch, great stuff. I want to ask you so I can better understand.

So in an exaggerated lean, its the soft material on the outer side of the tire that grabs and hopefully holds the traction, while the suspension is now somewhat asleep and not fully functioning.

 

The following schematic of a multi-compound tire cross-section is shamelessly stolen from Bridgestone's motorcycle tire technology pages:

 

 

To complete the answer, yes, the more you lean, the less your suspension is able to cope with the bumps and dips of the road surface.

 

But in a lesser lean (ridesmart) both the tire and the suspension are working in greater capacities together, sort of like sharing the responsibility, and more insurance for the rider.

 

I suspect you'd have to be leaning waaaay off AND not turning very tightly to end up riding on the hard (central) portion of a dual-compound tire; the latter detail (gentle turn) means you won't be asking for much traction out of your tires anyway.

 

Basically, if you're in a "sporting" turn and you lean off to the inside, you'll still be on the soft compound, AND you'll have put the bike's suspension in a better position to deal with bumps.

 

But in a straight away, we are using the harder part of the compound, and least amount of tire and traction, but compensating for that is the greatest degree of using our suspension.

 

In a straight, you're really not asking your tires for anything at all, unless you're accelerating or braking.

 

So Im thinking that my goal would be to ride in any situation in a way that allows all the relative pieces to share as much as possible an equal responsibility, offering as safe of a ride as possible. Am I on the right track with this.

 

The more margin-enhancing techniques/equipment/policies you develop/employ, the more likely you are to survive a situation that exceeds your initial expectations. (short answer: IMHO, yes.)

 

 

[Joe Frickin' Friday]

Don't forget you get more grip by applying more weight, which is also a factor when leaned over X degrees. Centripetal force adds "fake" weight to the tire, giving it more traction. As you reach 45 you start asking for more than 1G to keep the same constant radius.

 

Does that sound right?

 

I wish it were so. Unfortunately for us, the available traction force is dependent only on the force perpendicular to the pavement - and that force is only a function of gravity and vehicle mass, and doesn't change with speed, lean angle, turn radius, or any other parameter.

 

Think of it this way: as you're going through a turn, the pavement doesn't know/care whether you're a motorcycle that's leaned over, or a car that's sitting flat and level; the same rules of traction apply in each case.

[russell_bynum]

Don't forget you get more grip by applying more weight, which is also a factor when leaned over X degrees. Centripetal force adds "fake" weight to the tire, giving it more traction. As you reach 45 you start asking for more than 1G to keep the same constant radius.

 

Does that sound right?

 

I wish it were so. Unfortunately for us, the available traction force is dependent only on the force perpendicular to the pavement - and that force is only a function of gravity and vehicle mass, and doesn't change with speed, lean angle, turn radius, or any other parameter.

 

Think of it this way: as you're going through a turn, the pavement doesn't know/care whether you're a motorcycle that's leaned over, or a car that's sitting flat and level; the same rules of traction apply in each case.

 

Camber plays into that, though...right? Throw in some positive camber and some of the centripetal force is pulling you into the road.

[Joe Frickin' Friday]

Don't forget you get more grip by applying more weight, which is also a factor when leaned over X degrees. Centripetal force adds "fake" weight to the tire, giving it more traction. As you reach 45 you start asking for more than 1G to keep the same constant radius.

 

Does that sound right?

 

I wish it were so. Unfortunately for us, the available traction force is dependent only on the force perpendicular to the pavement - and that force is only a function of gravity and vehicle mass, and doesn't change with speed, lean angle, turn radius, or any other parameter.

 

Think of it this way: as you're going through a turn, the pavement doesn't know/care whether you're a motorcycle that's leaned over, or a car that's sitting flat and level; the same rules of traction apply in each case.

 

Camber plays into that, though...right? Throw in some positive camber and some of the centripetal force is pulling you into the road.

 

Just had to pile on one more factor, eh?

 

You're right, of course; with a banked road surface, centripetal acceleration increases the force against the road surface, which in turn increases the available traction. Predictably, I ran through the math - and I was surprised at just how effective road camber is.

 

If you assume a coefficient of friction of 1, on flat/level pavement you can lean the bike 45 degrees from vertical in a turn before a slide is imminent. You develop 1 "G" of lateral acceleration.

 

If you bank the road just 19 degrees, using the same tires you can now develop 2 g's of lateral acceleration before a slide is imminent. Lateral acceleration is proportional to the square of speed, so this means you can increase your speed through the turn by about 41%.

 

Bank the road a few more degrees, add some wings and sticky tires, and you can even get a CART race cancelled for fear of driver blackouts.

[David]

That's why at Daytona, with the extreme banking and allowable speeds, one of the hardest thing to do is hold your head up enough to see. All those Gs are forcing it into the tank.

[amz]

LOL! That's why we all love a nice "right" camber corner; and when riding through an 'off camber' corner, why 'KLM' really helps us keep the shiny side up...

 

Just look at the F1 drivers' necks, e.g. Raikkonen

[Joe Frickin' Friday]

That's why at Daytona, with the extreme banking and allowable speeds, one of the hardest thing to do is hold your head up enough to see. All those Gs are forcing it into the tank.

 

with a 31-degree bank on the oval at Daytona, you can hit over 4 g's lateral before traction is an issue (in fact probably even 5 or 6, since anyone on the track is probably using race-compound tires) - but just eyeballing the turn radius, I'd guess you've really gotta be hauling to hit the kind of speeds necessary to make that happen.

 

Still, if a head is 8 pounds, and a helmet is 4 pounds, and you even hit just three g's, then your neck is tryig to prop up 36 pounds...yikes...

[russell_bynum]

Bank the road a few more degrees, add some wings and sticky tires, and you can even get a CART race cancelled for fear of driver blackouts.

 

Yep.

 

I read somewhere that F1 cars make their own weight in downforce at only 80mph. So...in theory, an F1 car could drive upside down as long as it's going more than 80mph.

 

One some of the faster corners, an F1 car can make as much as 5-6g in lateral acceleration.

 

So....what do I need to do to fit front and rear wings to my Tuono?

[AnRSguy]

That's why at Daytona, with the extreme banking and allowable speeds, one of the hardest thing to do is hold your head up enough to see. All those Gs are forcing it into the tank.

 

And their eyeballs get smashed in to the bottom of their eye sockets too.

[FlyingFinn]

I read somewhere that F1 cars make their own weight in downforce at only 80mph. So...in theory, an F1 car could drive upside down as long as it's going more than 80mph.

 

That sounds about what I've heard too, pretty amazing when you think about that.

But the tremendous amount of down-force comes at the expense of really high drag coefficient.

So high, that at higher speeds (100+ mph) a F1 car decelerates at about 1G just by getting off the throttle!

1G just from the drag... Together with the brakes the peak deceleration can be over 5G.

 

--

Mikko

 

[David]

All this is testament to why it makes so much sense to have a large wing on the rear of a front-wheel drive Civic with a coffee can exhaust. They definitely are onto something.

[Little Joe]

First post on this topic, but I have read almost all of it.

 

A comment on the tone. IMHO, it is almost impossible to say "You're wrong" without ruffling feathers, regardless of how nicely you say it. The first agreement in any discussion should be the willingness to accept a direct contradiction of one's own position from the other party. And by accept, I mean listen to it respectfully, trying to see the logic of what is being said rather than focusing on the way it is said. Of course, that is easier to do when it is said with respect. It seems that everyone here has tried to do that.

 

I can understand what has seemed to be at times an emotional response from John (motorman587). He has been a lone advocate for his point of view in this thread, and that can reasonably engender feelings of defensiveness. More to the point, I'm not sure that his point of view has been clearly understood, which can be frustrating as hell.

 

Please correct me if I'm wrong, John. I don't hear you arguing that putting your weight on the inside of a turn will NOT decrease your lean angle. What I hear is that, given an appropriate entry speed and turn in point, any motorcycle designed to be ridden in the twisties (no OCC show bikes) can execute the turn, with lean angle to spare, while seated upright. And sitting upright confers a host of advantages (ease of visibility, not shifting the COG by moving your body, the ability to brake more quickly) that outweigh what you consider to be the relatively minor disadvantage of more lean angle. In fact, if you cannot execute a given turn without "kissing the mirrors", you either selected an inappropriate line, or you entered the corner going too damn fast! Do I understand correctly?

 

I'll buck the trend and agree with you to a point, if indeed I get what you're saying. We have lots of twisties near my home, and I am certain that you could navigate them more quickly than I could, while staying perfectly in line with the vertical axis of your RT-P. In fact, I followed a couple of guys riding FJR's on Hwy 49 that never changed their body position, and I quickly let them dust me and rode my own ride. I wonder if at least part of your argument is that to ride on the street any faster than YOU could seated upright, especially if it required hanging off or even KTM, is imprudent.

 

A couple of counterpoints. Having done a couple of track days, I gotta say that hanging off does allow me to navigate a turn more quickly because I have less lean angle, and it's fun to do! On the street, I try to KTM to a degree that is appropriate for each turn, because I have experienced the increased ground clearance it provides, and I feel more like I am piloting my bike. I know that last sentence opens up a can of worms (or squids), but I can't deny the sensation. I do focus on smooth, not fast. On those rare occasions when I have had to swerve to miss an obstacle, or commence braking until I see that the deer won't jump in front of me, I'm not aware of my moderate body lean as a hindrance to controlling the bike. YMMV.

 

The one point I haven't seen you address, and to me it is the strongest argument in favor of KTM, is this: what do you do when you encounter a decreasing radius turn, or in another poster's example, an encroaching Jeep? If you are at or almost at maximum lean, about all you can do is pucker and pray. You could argue persuasively that to get in that situation means you were going too fast. You may be right.

 

But it seems to me that, with KTM, I can ride at a "brisk" pace, under control, with a margin for error or unexpected hazard that is higher than if I remain upright. AND I feel a little bit like Rossi, even if I look nothing like him on or off the bike. So I will continue to try to improve my riding utilizing that technique. Hopefully I will get a chance to get some experienced instruction at a RideSmart course.

 

I have to say, John, I applaud your calm in the face of near constant negation of your POV in this thread. Thanks for adding to our overall body of knowledge on Riding Well.

[Little Joe]

All this is testament to why it makes so much sense to have a large wing on the rear of a front-wheel drive Civic with a coffee can exhaust. They definitely are onto something.

 

Flourescent orange paint jobs, 20" rims, and air dams save lives!

[David]

I can understand what has seemed to be at times an emotional response from John (motorman587). He has been a lone advocate for his point of view in this thread, and that can reasonably engender feelings of defensiveness.

 

I don't mean this as a smart ass comment, but maybe there's a clue hidden in there?

[lawnchairboy]

"I gotta say that hanging off does allow me to navigate a turn more quickly because I have less lean angle, and it's fun to do!"

 

My feelings, exactly...

 

[Twisties]

 

 

 

Ah, sweeper madness I presume.

 

Hope you don't mind me blowing these up a bit. In the first one you are showing exactly the issue/question I suggested in the very beginning of this thread, that has never yet generated any comment or discussion:

 

This is coming back down for a second pass. I think it looks wrong. Like my torso starts off leaning into the turn, but upper body hasn't followed, and the shoulders and head are almost vertical. I see this a lot when riding behind others. Sometimes only the hips are aligned with the seat, and the entire torso is vertical, or even counter-balanced. In this case I think it's just that I'm moving relatively slow and am very relaxed. If I were really into the turn, I hope my head would be over inside more. Or, it may just be that the shot is late in the turn, I may be starting to move the bike vertical. Not sure.

 

In your last shot there absolutely none of this. You appear to be fully aligned to me.

 

Great shots BTW!

 

Jan