Gymkhana skills in the real world

[Brian A]

At a steady speed into a curve your vehicle will be controlled by inertia and that external force can push you into the other lane (attempting to stop will take you into that lane) if going too fast but by putting power to the rear wheel it will change the inertia and the force will make your turn tighter..

Sounds good except for pretty much everything you said.

One sample: Inertia in NOT an external force.

Suggestion: Study Newton's First Law of Motion.

In the mean time, hope you don't crash.

Edited to add:  Do you really have an idea what you are talking about?

[klaviator]

That's not because of ...

You brought up a very good point that I completely forgot to mention; looking through the turn.  While this has nothing to do with physics it can make the difference between getting through the curve or crashing :respect-048:

Of course this is one of the keys skills in Gymkhana as well.

[Brian A]

And a FWIW comment: Kevin B is one of those guys I have ridden with. One of those guys I have been behind, beside and in front of at very brisk speeds.
He knows about that of which he speaks.

Based on my reading of your comments here, you possess uncanny, almost superhuman skills. You are a combination of Valentino Rossi and Graham Jarvis.

Please, share more.

[Slede]

this is one of those topics that would be really good in person

[Brian A]

If a bike does a casual 50 mph in curve without changing his speed and he finds it too fast for the curve and he will be straying into the wrong lane. (seen it many times) Trying to stop will often keep you headed in the way the bike is pushing into a possible collision. Giving it gas and power to the rear wheel will take you around that curve much easier because you are not fighting the inertia.
Works in cars too. It may not be expressed properly but it works.

The LAST thing I want to do if going too fast into a curve is to speed up.

WHAT ???  Have you any clue at all about the subject?

Give it gas and power to the rear wheel but the last thing one wants to do is speed up?

This is an interesting and fascinating concept.

Given the fact that a motorcycle is a vehicle which achieves forward motion as the result of "power to the rear wheel", how does one apply more power to the rear wheel and not speed up (because this is the LAST thing one would want to do) while at he same time managing to not fight inertia (which is the tendency of a body in motion to remain in uniform, straight line motion unless acted upon by an outside force) while dealing with the fact that the more momentum a body has, the more kinetic energy it has, so the more inertia it has.

It may not be expressed properly but it works.

Whatever "It" is, I'm betting a dollar to a nickle it ain't expressed properly and a dollar to a dime if you DID express it properly (as you are trying to explain it) anyone who attempted to apply the riding techniques you are describing would wind up in a ditch in very short order.



(side note - what have you NOT seen many times?)

[Chitza]

I failed physics. I just subscribe to the Slede school of motorcycle riding:

"When in trouble, shower on the throttle. It will either solve the problem or end the suspense."

Saved my ass in Alaska  :respect-058:

[Brian A]

Giving it gas and power to the rear wheel will take you around that curve much easier because you are not fighting the inertia.
Works in cars too.

DISCLAIMER - If you are describing applying sufficient power to the rear/drive wheels so that the tire(s) break traction and "drift" to the outside of the turn, then Yes, that is a legitimate technique for executing a turn.

But, not NOT because it has anything in the world to do with "inertia".

But... because it changes the net velocity/acceleration vector.

The easiest, quickest, most common example of this is to observe flat track motorcycle racing. They "give gas and power to the rear wheel" to take [them] around the curve much easier.

Is this what you are describing as a common technique for riding on the street?

[IceCold4x4]

Actually rolling off the throttle mid corner will make the bike run wider, and a bit more will help tighten a corner. This is of course predicated on the assumption you aren't already at the limit of traction. Watch twist of the wrist 2 for a more in depth example.

[Brian A]

MY APOLOGIES TO ALL.

This was meant to be a thread about "Gymkhana skills in the real world" and I believe I have been guilty of participating in a significant derailing of the thread.

Time for it to get back on track.

[klaviator]

MY APOLOGIES TO ALL.

This was meant to be a thread about "Gymkhana skills in the real world" and I believe I have been guilty of participating in a significant derailing of the thread.

Time for it to get back on track.

No need to apologize.  So what if we got a little off track.  This has been an interesting discussion.  It's my thread and I approve this message.

[klaviator]

Actually rolling off the throttle mid corner will make the bike run wider, and a bit more will help tighten a corner. This is of course predicated on the assumption you aren't already at the limit of traction. Watch twist of the wrist 2 for a more in depth example.

I don't have time right now to watch this video but I think you have it backwards.  Keep in mind that if you accelerate the bike will go faster and require more lean angle to maintain a steady turn.  If you decelerate then keeping the same lean angle will cause your line to tighten up.  There are a few other factors that complicate all this.  For one, when you roll into a curve you need some additional throttle just to maintain a constant speed since the edges of tires have a smaller circumference than the middle of the tire.  Second, depending on chassis geometry and tires, chopping the throttle MAY cause the bike to want to stand up and run wide.  I would guess that if your bike tends to stand up under braking it might also want to stand up if you chop the throttle.  Regardless, if you slow down you can tighten your line with proper steering inputs. 

Here's a quote from an article on cornering as well as the link to the entire article:

"Note that acceleration typically makes the bike drift wide and deceleration can either cause the bike to drop into the corner more or cause it to stand up, depending on how abruptly the throttle is chopped and how the machine /tire combo responds to this input."

http://www.ridinginthezone.com/how-not-to-suck-at-cornering/

Regardless, if you are going into a curve too hot, rolling on the throttle is NOT the best way to make it around the curve. 


I did take the California Superbike school.  Keith code did recommend rolling on the throttle as the fastest way around a curve but he was assuming that you slowed down enough before the curve to be able to do this.  Also there are plenty of racers who don't agree with this technique and trail brake into the curve and roll on the throttle once past the apex as they start to stand up the bike and accelerate out of the curve.

[klaviator]

While it may seem that we have drifted away form the original topic, I would argue this is all relevant.  One of the great things about gymkhana is that you can practice a lot of the skills needed to ride your bike at lower speeds and in a controlled environment.  You do get to experience what happens when you roll power on or off in a curve or brake in a curve.  These skills still apply at higher speeds although there are obviously some differences in how you bike responds at higher speeds.  Whether you are riding at low or high speeds the laws of physics do not change and neither do your bikes controls. 

[IceCold4x4]

The short version of what I got from the video is that the weight transfer to the front from going off throttle increases the size of the front contact patch and that causes the bike to try and stand up. It's not a permanent running wide deal as once more speed is bled the bike will indeed turn tighter. I've tested the theory by rolling on and laying off throttle mid corner and find that a bit more throttle will tighten a line and less will go a bit wider. This was on my zrx and the old Vulcan 750. Haven't tried it on a dirt bike yet...

Needless to say the physics that control a 2 wheeled vehicle are rarely ever truly simple and generally have a laundry list of variables and things to account for.

I'll never claim to be the next rossi and have yet to do a track day so my observations are all street related and performed likely way under the limit of what the bike is capable of.

However bench racing is always a nice diversion.

Sent from my SM-N950U using Tapatalk

[Chitza]

In the MSF course, I was taught when approaching a curve you use the following sequence:

SLOW - reduce your speed to a safe speed to enter the curve, by rolling off the throttle or braking BEFORE the curve
LOOK - through the turn to your exit point
PRESS - countersteer
ROLL - roll on the throttle as you exit the curve

All of this with the outside, inside, outside path through the curve
(Outside being the half of the lane opposite the curve, so for a left hand turn, you would set up to the right side of the lane. The inside would be same as the turn, as in the left hand turn, left side of the lane).

What I have learned after much anguish and over analyzing is that practice improves the skills and creates muscle memory that can get you out of a bind quickly. Reaction times are quicker if you don't have to think about what to do. Your mind/body simply react.

[klaviator]

In the MSF course, I was taught when approaching a curve you use the following sequence:

SLOW - reduce your speed to a safe speed to enter the curve, by rolling off the throttle or braking BEFORE the curve
LOOK - through the turn to your exit point
PRESS - countersteer
ROLL - roll on the throttle as you exit the curve

All of this with the outside, inside, outside path through the curve
(Outside being the half of the lane opposite the curve, so for a left hand turn, you would set up to the right side of the lane. The inside would be same as the turn, as in the left hand turn, left side of the lane).

What I have learned after much anguish and over analyzing is that practice improves the skills and creates muscle memory that can get you out of a bind quickly. Reaction times are quicker if you don't have to think about what to do. Your mind/body simply react.

The MSF really does their students a big disservice by making a big deal about not braking while in the curve and leaned over.  A lot of riders now have the idea that you shouldn't touch the brakes while leaned over.  This is TOTAL BS.   While there are many who advocate completing your braking BEFORE the curve, Braking while IN the curve is a very useful skill that EVERY rider should have.