The Vanishing Point

[budman]

Sweet Dan... another

 

[BigMatt408]

I have already started practicing this, it is helping out a lot!

 

[Zerox]

It is painful and sobering to see that phuzzy3d posted in this thread earlier this year.

 

[Dr_SLO]

The VP is an excellent guide for interpreting unfamiliar turns. The VP can also be 'increased/decreased' by minor changes in road positioning. Riders who like to find the best apex for the fastest speed through a turn will tend to turn in earlier. As this thread, I believe, is for improved riding on unfamiliar roads the fastest (read shortest) line through a corner is not necessarily the best to take for reading the road ahead.

To increase and prolong the VP it's useful to position the motorcycle as far to the left (towards the centre line for right hand corners) or as far to the right (towards the fog line for left hand corners) as it is safe to do so. This is explained in Motorcycle Roadcraft. Keeping this position through a corner will extend and prolong the VP but it will mean you'll not apex the corner.

This technique, plus 'right gear for the right speed' has helped me a lot on unfamiliar roads for years. Hitting an apex is great for open roads where the vanishing points are a long way off or for the race track. You never know what to expect around the next corner, especially on roads in the Bay Area and beyond...

 

[hobbes]

I nominate this thread for sticky status. All in favor?

Aye!

Probably best of BARF rather than a sticky.

 

[VaderSS]

Bump for a powerful tool!

 

[VFRrider]

I use this everytime I get on the bike. thanks dan

 

[PastRedline]

I have a question on this that may seem stupid, but I just want to make sure that I understand.

In my MSF course, and riding with several friends, I was always taught to begin a gentle roll-on as soon as I got leaned in. Not for acceleration but rather to get the weight to the back of the bike.

It sounds like, according to this technique, that if I have a decreasing radius turn, I would end up rolling off the throttle mid-turn (which has always been described to me as a good way to find myself in the dirt, wondering what happened).

Could someone clarify this for me slightly?

Thanks,

Kyle

 

[DataDan]

I have a question on this that may seem stupid, but I just want to make sure that I understand.

In my MSF course, and riding with several friends, I was always taught to begin a gentle roll-on as soon as I got leaned in. Not for acceleration but rather to get the weight to the back of the bike.

It sounds like, according to this technique, that if I have a decreasing radius turn, I would end up rolling off the throttle mid-turn (which has always been described to me as a good way to find myself in the dirt, wondering what happened).

Could someone clarify this for me slightly?

Glad to. And it's a good question.

The technique does not recommend rolling off in mid turn. Until the VP begins to recede, you haven't reached the tightest part of the turn. As long as it's getting closer, you continue to slow because you don't yet know how tight the turn is. You need to be able to lean farther if it continues to tighten, so you don't want to be on the gas yet.

When you're no longer closing in on the VP and it is staying a constant distance ahead, you're looking at the tightest part of the turn (see pics 5 and 6 of the photo sequence). This is the key transition. When the VP is at a constant distance ahead you can commit to lean angle and begin to roll on the throttle--as you say, not for acceleration yet, but to stabilize the bike.

 

[Aluisious]

I like the first way this is explained in the OP because it's so succinct, common-sense oriented, and everything you need to know flows out of it:

Don't ride so fast you can't see where your stopping point would be.

If people would do that it would fix so many problems encountered in the hills...

 

[Underdog]

I have a question on this that may seem stupid, but I just want to make sure that I understand.

In my MSF course, and riding with several friends, I was always taught to begin a gentle roll-on as soon as I got leaned in. Not for acceleration but rather to get the weight to the back of the bike.

It sounds like, according to this technique, that if I have a decreasing radius turn, I would end up rolling off the throttle mid-turn (which has always been described to me as a good way to find myself in the dirt, wondering what happened).

Could someone clarify this for me slightly?

Thanks,

Kyle

Actually, rolling on the throttle moves the weight FORWARD not backwards. This allows the chassis to settle down and stabilize.

If you correctly set your entry speed to a turn, you wouldn't ever need to roll off the throttle. If it's a decreasing radius turn, leaning in (WHILE maintaining throttle) will suffice.

 

[budman]

Actually, rolling on the throttle moves the weight FORWARD not backwards. This allows the chassis to settle down and stabilize.

If you correctly set your entry speed to a turn, you wouldn't ever need to roll off the throttle. If it's a decreasing radius turn, leaning in (WHILE maintaining throttle) will suffice.

Quick comment.

I have always found when the gas is applied it transfers weight to the rear.
Rolling on will minimize the amount, but will help settle the chassis so weight is leveled out/stabilized as noted above.

And it is not true all the time that maintaining throttle will suffice. If you have judged things correctly true.. if you have not then the "throttle on" will force you to lean more to maintain the turn = a more severe lean angle required for the additional speed.

Closing the throttle will apply more weight to the front.. if your not going way too fast the bike should still track thru in most cases. If you are going to fast chopping the throttle late in the turn can put you on your ass...fast.

I find that if you feel you are going to fast, most of the time you can chop the throttle as long as you are not already in much of a lean... and you can still make the turn. This is different on every bike and really best explored on the track.. and is a real moment on the street for new riders and experience a like.

Leaning further than your comfortable with is scary.. but bikes really do go to some pretty decent angles and IMO this is your best chance to make it thru.
Just stay off the brakes.. and hope

 

[Underdog]

Quick comment.

I have always found when the gas is applied it transfers weight to the rear.

There are ways of proving that, I'd be happy to supply that claim, K.Code on TwistOfTheWrist has proof as well.

And it is not true all the time that maintaining throttle will suffice. If you have judged things correctly true.. if you have not then the "throttle on" will force you to lean more to maintain the turn = a more severe lean angle required for the additional speed.

Agreed. These level of freedom interact as said. It's your choice whether you want to lean+throttle or keep your line and maintain throttle. Following the line-of-sight scenario, I assumed you have correctly judged your entry speed based on what you can see. If you find yourself at a decreasing radius turn, you may choose to lean more and add more throttle.

I find that if you feel you are going to fast, most of the time you can chop the throttle as long as you are not already in much of a lean... and you can still make the turn. This is different on every bike and really best explored on the track.. and is a real moment on the street for new riders and experience a like.

I'd rather not go there. Newbies are often told to use the clutch to slow down when needed.

Leaning further than your comfortable with is scary.. but bikes really do go to some pretty decent angles and IMO this is your best chance to make it thru.

+1. Sport bikes can lean PLENTY. Much more than you'd ever want to do battle with on the street anyway.

 

[PastRedline]

Great answers, guys. Thanks for taking the time to clarify for me.

My understanding is this:

1) Don't roll off the throttle mid-turn (you might get away with it, but it builds bad habits, too quick of a chop and you'll almost certainly have an off-bike experience). The usual advice applies - if you think you're going too fast, lean harder and correct the mistake next time.

2) When used correctly, the VP technique will have you holding a line at the outside of the turn with deceleration until the VP distance goes steady, at which point you should be in more of a maintenance throttle mode, and then when you see the VP start to get further away, commit to a lean angle and roll on.

Please let me know if I seem to have gotten the gist of it.

Thanks again,

Kyle

 

[tzrider]

And it is not true all the time that maintaining throttle will suffice. If you have judged things correctly true.. if you have not then the "throttle on" will force you to lean more to maintain the turn = a more severe lean angle required for the additional speed.

Bud, this is true if the bike picks up significant speed in the corner. Merely cracking on the gas doesn't result in the bike gaining speed (unless we're in a steep downhill turn). In fact, if the throttle is only open to the setting that would have maintained speed in a straight line, the bike will slow down in the turn because of the increase in friction from the turn against the unchanged thrust coming from the engine. It takes a little increase in throttle just to maintain the speed you carried into the corner. The rider can accomplish this by slowly rolling on the gas through the turn. As long as the speed remains about the same, the lean angle can too, unless the rider must tighten his line.

If the rider does accelerate in the turn, he will need to increase lean angle if he's on a constant radius line.

There are ways of proving that, I'd be happy to supply that claim, K.Code on TwistOfTheWrist has proof as well.

I think you've misunderstood Keith if you have the idea that rolling on the gas transfers weight to the front. He does not say that anywhere.

What you may be thinking of is what he writes in TotWII, Chapter Three, "Throttle Control, Suspension and Traction." In the sub section "Rear Suspension and Gas," (page 14 in my copy) he describes how the rear suspension tends to rise when the rider is on the gas. This is not a description of weight transfer, it is a description of how the rear suspension behaves when torque from the rear wheel is applied to the swingarm. Under these conditions, the torque causes the swingarm pivot to rise, despite the fact that weight is transferring rearward. This isn't a nitpick; it's pretty important to understand.

 

[DataDan]

2) When used correctly, the VP technique will have you holding a line at the outside of the turn with deceleration until the VP distance goes steady, at which point you should be in more of a maintenance throttle mode, and then when you see the VP start to get further away, commit to a lean angle and roll on.

Please let me know if I seem to have gotten the gist of it.

Correct. When the VP is staying at a constant distance, you're approaching a constant-radius section of turn. At that point, you steer and begin to roll-on the gas.

See the last pic in the photo sequence, the aerial with sightlines drawn in, to better understand the relationship between the radius of turn in front of you and the progress of the VP.

 

[budman]

Agreed Andy... good point.. I was comparing throttle off --scrubbing speed-- throttle on would be maintaining as you pointed out or on more.. adding speed.

Very important aspects for the new rider to understand

 

[Robin]

Good stuff Dan
One can also use other objects to further 'read' a corner. Hedgerows, lamp posts, power lines can give you a feel for where the road goes when it becomes blind.

 

[izzy_OCR]

I'd rather not go there.Newbies are often told to use the clutch to slow down when needed.

Hi can you explain this to me "I'd rather not go there.Newbies are often told to use the clutch to slow down when needed."Do you mean, newbies hold the clutch in and to slow down? I've been riding for a couple of years, and there have been time when, I'll be going into a turn too fast; so what I do is, I squeeze the front brakes hard to slow down a little bit then down shift a gear! As a Vet. (I'm guessing) how would you handle this, when you are going to fast into a turn, I know you would want to lean and have a steady line but, what I'm doing is right??

 

[Bumble6ee]

Very useful info, thank you!

 

[sanjuro]

I was reminded about this today on my bicycle commute.

I was headed downhill to a right turn on a tight street. I've could have easily hit the turn doing 20mph but there were a parked SUV blocking my vision.

I slowed down to probably 10mph and instead of making a wide turn which would have put me into the middle of the street, I took an angle closer to 90 and was able to keep the turn tight.

Good thing because a car was driving down the middle of this very tight street, and I was able to squeeze by even though instead half the road, I barely had the width of a bike lane.

If I had gone full speed, I would have ended up in the middle and I would have gone into the windshield.

When I am on my motorcycle, I tend to take all street turns rather cautiously because the variables are much greater than the highway. But the line of sight is the most important factor in navigating the streets.

 

[latindane]

DataDan, the link on your first post sent me to an AT&T net "content blocked" page; would it be possible for you to attach the pics to the thread? I think they would help me visualize the technique...

 

[DataDan]

DataDan, the link on your first post sent me to an AT&T net "content blocked" page; would it be possible for you to attach the pics to the thread? I think they would help me visualize the technique...

Thanks for finding that. The server space I used to have through AT&T is no longer available. Photos now appear in the OP of this thread, inline with the text.

 

[latindane]

Very nice post! Thank you Dan for uploading the pics. I had heard about the vanishing point, but thought it was a way to keep your sight focused far ahead from the (where you want to go). Will give this one a try next time I'm on the road.

Thank you for taking the time to write this kind of posts for the benefit of the rest of us.

 

[DataDan]

Here's a vivid real-world example of how the VP can help you to judge a turn.

The General thread Crash on HW9 this afternoon (3/28/10) - Rider airlifted is about a crash that occurred on a notorious blind, decreasing-radius right-hander. Misjudging the turn, the rider ran wide at the exit and hit an oncoming pickup (not head-on, but at the rear wheel).

If you have Google Earth, you can follow the turn on which the crash occurred from the same point of view the rider had. Go to 20716 California 9, Boulder Creek, CA. The turn is just south of that location (though nominally north, since that's the direction to Skyline), a right-hander marked with a 25mph warning sign. Click one of the street view icons and rotate your view so you're behind the red Corvette. Follow the Vette through the turn, taking note of the distance to the VP.

What do you notice about the progress of the VP through the turn? At what point would you commit to a line?