Lean angle in turns

[russell_bynum]

Mitch, Russell, and Jake nailed it...

 

One thing though, you mention your transverse twin with no hope of hitting your cylinder head, how about your foot, or footpegs, or centerstand/kickstand, exhaust? Any of those things lower on the bike than the heads? I thought that might be the case...

 

NO Sir, None of those parts will ever touch the road; not the way I lean in the turns.

I like to take turns semi fast, but I know my limit. A few years ago coming back from Big Bend Nat. park in Texas heat, on a road infested with tar-snakes...the tar-snakes HAVE put the fear in me.

I was on my Rt1200 and almost lost it, just barely being able to make the turn. I leaned but the bike kept sliding little by little on melted tar toward the edge of the road. It was a very close call.

I am not getting any younger, and it seems thing hurt a lot more nowdays than when I was younger. I want to be able to enjoy motorcycling a for a little wile longer.

This is my story and I am sticking to it!

 

Don't confuse "How I intend to corner." With "How I had to corner because the corner tightened up, an idiot appeared on my side of the road going the wrong way, I had to take evasive action to avoid a deer, etc."

 

If you can do something that will minimize your lean angle and therefore maximize available traction and options...why wouldn't you?

[Bud]

If you just slow down enough, you can corner perfectly upright. You guys just always are riding way to fast.

 

The last time I rode way to fast was behind you on the BRP!

 

And a voice in my helmet (or inside my head) was screaming at me LEAN< LEAN< LEAN

 

I dialed it back a couple of notches (except when I passed all those Harley riders that didn't want me to go by them) and caught up with you later.

 

They don't call it "Chasing Bernie" for nothing. :

 

[Bill_Walker]

One thing I'd like to add that nobody has mentioned: dirt bikes have huge ground clearance. Thus, you can lean a dirt bike way, way over before anything hits the ground. Dirt bikes in their natural environment are also traction-limited. There's no way, if the rider leaned into the turn, that they have enough traction to lean as far as the bike can lean. The tires would slide out. (or so I think, based on my limited dirt experience and some observation). Corners are generally quite sharp and are generally taken relatively slowly (compared to a road bike). So it makes sense, on dirt, to lean the bike down and the body up (just like it does to do so on a street bike at parking-lot speeds).

 

Switch to a high-traction, low-ground-clearance bike and the rules are different.

[David Langford]

body first on street and bike first on dirt, anybody wants to do it different - its a free country, but us that ride both avidly know this.Why ague with the one who disagree with the pro's

[racer7]

+1

[mneblett]

I just read all of the above, and it struck me that no one put it this way:

 

1. Every motorcycle has a point at which its tires will lose their grip on the road (influenced by tire temperature, ambient temperature, etc.). In normal conditions with most street bikes, it is the point at which something touches down and unloads the tires.

 

2. When a bike goes around a corner with the rider aligned with the bike (a rider/bike "neutral" condition), the bike *must* be at a certain lean angle, determined solely by the radius of the turn and the bike's tangential velocity (i.e., speed).

 

3. If you are not at the maximum lean angle before losing it, then the "neutral" lean angle for that turn radius and bike speed is xx degrees smaller (more vertical) than the maximum lean angle before pavement surfing.

 

4. The difference between the lean angle you are at and the maximum lean angle before the bike/rider slide off into oblivion is the amount of lean angle "margin" you have left.

 

Aside: Some call the lean angle margin the "amount of traction left," but that leads to terminology arguments, because some think of "traction" is the coefficient of friction between the tire and the road -- which itself is misleading because the "traction" issue that *really* matters is the amount of lateral acceleration the tire can generate at a given lean angle (a function of the coefficient of friction *at that angle* (it's not the same friction coefficient at every angle), the normal force being applied, the non-linear characteristics of the rubber compound, its microscopic distortion relative to the road surface, etc.).

 

So:

 

If you lean in/move inside the bike, because physics requires the combined CG of the bike and rider to still follow the path of the "neutral" CG through the turn (because the turn radius and tangential velocity haven't changed), the rider's CG being inside ("leaning more") requires the bike to be leaning less (in order to maintain the same turn radius/speed combined CG on the same path as the "neutral" path around the curve). That means the bike's lean angle "margin" before the "aw chit" lean angle is increased by the rider leaning in.

 

In other words, by leaning in, you increase the "lean angle reserve" you have available to respond to the unexpected.

 

 

Similarly, if you lean out, the bike must be leaned in more to keep the combined CG's path on the same path as the "neutral" CG path.

 

In other words, leaning the bike further in takes away from the amount of "lean angle reserve" you have left before the tires can no longer push the bike around the turn.

 

 

Physics conclusion: Lean in on the street to increase the margin of safety, by increasing the amount of available reserve lean angle before the disaster lean angle is reached.

 

 

Pot sufficiently stirred??

[SuperG]

Excellent post...and there is nothing in the pot to to stir.

 

This explanation is much better then just saying "just do what the PROs do, and don't argue".

 

It's all good...looks good from here.

thanks

[russell_bynum]

Physics conclusion: Lean in on the street to increase the margin of safety, by increasing the amount of available reserve lean angle before the disaster lean angle is reached.

 

Correct.

 

But...keep the other variables in mind and do what's prudent.

 

For example: You could take "lean in" to the extreme by hanging off the bike like a roadracer does. That would certainly decrease your lean angle and therefore give you more available lean (margin.)

 

But...The further off the bike you get, the harder it is to get back on the bike where you can change direction, should the need arise. This is less of an issue on the track where you always know where the next turn goes, the other vehicles on the track with you are relatively predictable, and you've got corner workers showing you flags to let you know that something ahead needs your attention. On the street you don't know where the next turn goes, and you don't have anyone waving a flag to tell you that there's a crash in the next turn, and you have people going both directions on the road, pulling out of side streets. You need to factor that into your decision-making process. Generally that means you slow down. You may also do things like square off the turns (which forces you to lower your entry speed), etc. And instead of hanging off, you will likely use much less extreme body position (i.e. "Kiss the mirrors") since that makes it easier to change course if the need arises. You are trading lean angle (speed and/or margin) for the ability to change course more easily.

[mneblett]

But...keep the other variables in mind and do what's prudent.

 

For example: You could take "lean in" to the extreme by hanging off the bike like a roadracer does. That would certainly decrease your lean angle and therefore give you more available lean (margin.)

 

But...The further off the bike you get, the harder it is to get back on the bike where you can change direction, should the need arise. ...snip...

Agreed.

 

From my perspective, if someone is on a public road and regularly traveling fast enough that leaning in makes the difference between making the turns and not, he/she is an idiot, and should be placed in "time out."

 

Sure, *everyone* once in a blue moon gets caught out by a surprise, and in that situation leaning in and staying on the power is likely the best thing you can do.

 

But there's difference between misjudging a single turn and having to move to the inside to save your tail, and intentionally riding at that level. Even if you are as good as Valentino Rossi (or in my day, Kenny Roberts), if you're constantly at that edge of the envelope on the street, you're a menace to others (I don't really care about the idiot, Darwin will address that branch of the evolutionary tree at some point) and should be nailed for it.

[russell_bynum]

But...keep the other variables in mind and do what's prudent.

 

For example: You could take "lean in" to the extreme by hanging off the bike like a roadracer does. That would certainly decrease your lean angle and therefore give you more available lean (margin.)

 

But...The further off the bike you get, the harder it is to get back on the bike where you can change direction, should the need arise. ...snip...

Agreed.

 

From my perspective, if someone is on a public road and regularly traveling fast enough that leaning in makes the difference between making the turns and not, he/she is an idiot, and should be placed in "time out."

 

Sure, *everyone* once in a blue moon gets caught out by a surprise, and in that situation leaning in and staying on the power is likely the best thing you can do.

 

But there's difference between misjudging a single turn and having to move to the inside to save your tail, and intentionally riding at that level. Even if you are as good as Valentino Rossi (or in my day, Kenny Roberts), if you're constantly at that edge of the envelope on the street, you're a menace to others (I don't really care about the idiot, Darwin will address that branch of the evolutionary tree at some point) and should be nailed for it.

 

This is a sentiment we hear often.

 

What it fails to consider is that the most prudent rider is both going slow enough that leaning in is not necessary AND leaning in anyway so that when it does become necessary, they're already doing it.

 

I hit something slippery while making a left-turn at an intersection once. I was in a line of traffic coming off a red light, so my speed was pedestrian to say the least. Because I was already leaning in, it was easy to just push the bike up even farther (Keith Code calls it the "pick-up drill") while feathering the throttle. The bike didn't fall over (since I had it mostly upright thanks to my body position and the "pick-up" I did and when I passed whatever was slippery in the road, I got a little shudder as the rear regained traction and stepped back in line. Minimal drama. If I'd been sitting upright fat, dumb, and happy, I probably would have crashed.

 

A flight instructor friend once asked me "Why would anyone ever do anything other than a short-field takeoff or landing?" It's a great point...why would you intentionally leave yourself less margin than is necessary?

[Dave_zoom_zoom]

Thanks Mark!

 

I think you summed that up rather nicely.

 

 

 

 

Very good Russell!

 

Your points are very well taken.

 

 

 

 

 

I see no conflict here. Just different choices in application.

 

Dave

 

 

[mneblett]

This is a sentiment we hear often.

 

What it fails to consider is that the most prudent rider is both going slow enough that leaning in is not necessary AND leaning in anyway so that when it does become necessary, they're already doing it.

It doesn't fail to consider that, it is talking about something different. Perhaps I was not clear enough.

 

Leaning inside the turn is a very **good** thing to be routinely doing, even if you are nowhere near the limit (as in your example -- leaning in even at that slow speed set you up nicely for the unexpected). I do so in my daily commuting, too, when/where appropriate.

 

My comment was directed to an entirely different range of bike operation: idiots that are going so fast on public roads that they *have* to hang off, else they'll run off the turn -- those folks should be banned from two wheels until they acknowledge the hazard they are creating and start riding like they recognize they have an obligation to avoid endangering others.

[Matts_12GS]

Agreed.

 

From my perspective, if someone is on a public road and regularly traveling fast enough that leaning in makes the difference between making the turns and not, he/she is an idiot, and should be placed in "time out."

 

Sure, *everyone* once in a blue moon gets caught out by a surprise, and in that situation leaning in and staying on the power is likely the best thing you can do.

 

But there's difference between misjudging a single turn and having to move to the inside to save your tail, and intentionally riding at that level. Even if you are as good as Valentino Rossi (or in my day, Kenny Roberts), if you're constantly at that edge of the envelope on the street, you're a menace to others (I don't really care about the idiot, Darwin will address that branch of the evolutionary tree at some point) and should be nailed for it.

 

 

So judgmental... Much along the lines of Carlin's "jackasses and maniacs" (paraphrased to please the demigods of PC) wherein anyone who passes you is a maniac and anyone slower is a jackass.

 

This type of inflammatory statement takes nothing into account the skill of another rider, only your perception/emotional reaction to be slowed down or passed.

 

I'll never ride at a track pace on the street, but I certainly have no fear of stepping over a speed limit now and then. And I am as safe and courteous as I can be to avoid that same jackass/maniac thing from those I pass. I want them to see a rider in gear acting safely and seeming to enjoy himself by testing his own limits.

 

I would advise learning to ride as well as possible and not worrying about any kind of comparison against anyone but you.

just my $.03 (accounting for inflation... )

[russell_bynum]

My comment was directed to an entirely different range of bike operation: idiots that are going so fast on public roads that they *have* to hang off, else they'll run off the turn -- those folks should be banned from two wheels until they acknowledge the hazard they are creating and start riding like they recognize they have an obligation to avoid endangering others.

 

Totally agree. ...though it's rare to see people going fast enough that they actually have to hang off. Most of the people you see hanging off on the street don't know what they're doing and can easily be passed by a 2-up R1100RT while the passenger turns around to take their picture.

 

Or....so I've heard.

[mneblett]

Or....so I've heard.

 

Lol'd -- made my day!

[mneblett]

So judgmental...

Yep. I have no patience for those that selfishly put others at risk.

 

This type of inflammatory statement takes nothing into account the skill of another rider, only your perception/emotional reaction to be slowed down or passed.

I believe you've missed the point -- this is not about someone driving faster or slower than me (I couldn't give a rat's pootuty about whether someone passes me -- although frankly, it's not that often).

 

It is about people (regardless of their skill level) riding at 10/10 (for their skill level) or taking away someone else's safety margins (like blasting past within inches in the same lane) when/where their actions can hurt someone else.

 

I'll never ride at a track pace on the street, but I certainly have no fear of stepping over a speed limit now and then. ... I want them to see a rider in gear acting safely and seeming to enjoy himself by testing his own limits.

I do exactly the same -- my GPS's speed readout is rarely not red. But I don't do it in a way that puts an innocent party at risk.

 

That's not being judgmental in the sense of saying that someone that rides fast relative to me is "bad," it's judgmental in the sense that I believe no one should be allowed to create a substantial risk of harm to others. Saying "I'm that good" is not an excuse for riding that close to the edge of the envelope when/where others might be hurt.

 

If someone wants to take a chance on flying off into a canyon when no one else is around, fine. Darwin will sort out the winners and losers -- without anyone else paying for it.

[russell_bynum]

Or....so I've heard.

 

Lol'd -- made my day!

 

Professional rider. Closed course. Do not attempt. Void where prohibited by law. YMMV.

 

The best reaction I...er....I mean....a friend of mine got was when he ran down a group of crotch rockets in the twisties...on a DRZ400 on knobbies. Their faces when they finally caught up to me him at the stoplight at the bottom of the canyon was priceless.

[lkchris]

Reminds me of my favorite thing from a motorcycle mag a long time ago.

 

It was a statement from King Kenny Roberts who related the time he was out riding a Ducati Elephant (early GS clone) and came upon some crotch rocket guys that wanted to have some fun. Roberts related that he refused because he had too many monetary assets at risk should he be sued.

 

King Kenny is widely credited with inventing knee dragging and it was also noted that his ability to win at the world top level road racing came significantly from his bringing dirt tracking expertise to the game. There wasn't a lot of tire sliding in road racing at the time but if you watch #93 in MotoGP now it's unbelievable how much there is.

 

A couple points I think not mentioned so far ...

 

The lean angle shown in the #93 photo isn't possible at street speeds. Lot of that traction is created by centrifugal force.

 

I think a lot of leaning into the turn also involves leaning forward. The guy leaning opposite is maintaining his preferred upright position and locked straight elbows.

 

Electronic traction control is the future. In one 2013 race #93 was side-by-side in a corner with his teammate #26 and leaned enough into his teammate's bike that he broke or disconnected some traction control wiring. #26 high sided within 20 feet without it.