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Old 04-18-2012, 11:43 AM   #81
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Quote:
Originally Posted by texlurch View Post
Centrifugal force on any object traveling in an arc or circle acts in the same direction.. out.

If it didn't, you wouldn't even have to lean the bike to counteract it.. just turn that wheel.

Fact: for a given radius, you have to lean more as speed is increased.. even tho you are still carving the same arc and line (body in the same spot)..

why is that?

Because as speed increases, so do the centrifugal forces trying to stand the bike up.

The only way to counteract that is move more weight in and lower...

Regardless of the affect the change in tire radius and steering angles etc etc, the force you are countering is the one trying to stand the bike up.
You don't understand the centripetal forces of the wheel. Newton's first law invalidates your idea that the centripetal forces act in the way you suggest: the wheel, once forced into the lean stays there until acted on by an outside force. What outside force makes it stand up? Here's a video demonstrating something spinning at an angle. It doesn't try to stand up.

Gyroscope - YouTube

not embedded so that it's fast forwarded to the pertinet part.

EDIT: nevermind, Mh now auto-embeds. Fast forward to 2:18.
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Last edited by Chubby Racer; 04-18-2012 at 11:47 AM.
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Old 04-18-2012, 11:46 AM   #82
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Quote:
Originally Posted by po-po 5.0 View Post
You don't understand the centripetal forces of the wheel. Newton's first law invalidates your idea that the centripetal forces act in the way you suggest: the wheel, once forced into the lean stays there until acted on by an outside force. What outside force makes it stand up? Here's a video demonstrating something spinning at an angle. It doesn't try to stand up.

Gyroscope - YouTube

not embedded so that it's fast forwarded to the pertinet part.
Don't cars have wheels that too act as gyros? They won't maintain a turn if you let go of the wheel
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Old 04-18-2012, 11:48 AM   #83
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Quote:
Originally Posted by Bevo View Post
Don't cars have wheels that too act as gyros? They won't maintain a turn if you let go of the wheel

Cars have totally different dynamics owing to having 4 wheels, and wide and flat contact patches.
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Old 04-18-2012, 11:49 AM   #84
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Quote:
Originally Posted by po-po 5.0 View Post
Cars have totally different dynamics owing to having 4 wheels, and wide and flat contact patches.
Get a throttle lock and a GoPro and show us your results
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Old 04-18-2012, 11:52 AM   #85
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To answer OP.

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Old 04-18-2012, 11:57 AM   #86
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If the spinning wheels were the only dynamic involved, you would be correct.

If the wheels were spinning, leaned over, in a straight line, sure.

Once you start them into an arc, they want to stand back up.

The centripetal force of the spinning wheels is what makes the bike want to stand up and go straight, and resist changes in direction.. hence the reason you countersteer to change the slip angle of the front wheel, causing the bike to lean over.. the wheel then turns back into the turn.. otherwise you will turn not much at all.

You have to figure in the force acting on that 400 lbs + mass sitting 3 feet off the ground traveling in a circle.
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Old 04-18-2012, 12:05 PM   #87
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Quote:
Originally Posted by texlurch View Post
The centripetal force of the spinning wheels is what makes the bike want to stand up and go straight
no

Quote:
Originally Posted by texlurch View Post
and resist changes in direction..
yes






these two things are contradictory. The centripetal forces EITHER resists changes in direction OR makes it stand up and go straight. It ain't both. Netwon's first law tells us its the former.
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Old 04-18-2012, 12:14 PM   #88
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Quote:
Originally Posted by AaronP220 View Post
I followed you an entire session that day. Yer knee didn't go down once. LOL.

CLOSE. But not actually down.

You didn't look closely enough. Bevo has realized the only way to protect those knee pucks is to use something that is more durable than the puck but still smooth on the track surface. When it comes to tough and smooth there is only one thing that will do the job. Bevo himself.

picturephp?albumid608&amppictureid3262
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Old 04-18-2012, 12:16 PM   #89
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Quote:
Originally Posted by kibitzer View Post
You didn't look closely enough. Bevo has realized the only way to protect those knee pucks is to use something that is more durable than the puck but still smooth on the track surface. When it comes to tough and smooth. There is only one thing that will do the job. Bevo himself.

picturephp?albumid608&amppictureid3262


Use this pic

1 b6a27a2b
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Old 04-18-2012, 12:27 PM   #90
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lol..this freaking thread is full of wins!
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Old 04-18-2012, 12:32 PM   #91
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I thought this thread was about something COMPLETELY different....

original tebow 495x371
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Old 04-18-2012, 12:33 PM   #92
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Quote:
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I thought this thread was about something COMPLETELY different....

original tebow 495x371
I hope you fall and break your tebown for posting that.
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Old 04-18-2012, 12:39 PM   #93
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Quote:
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I hope you fall and break your tebown for posting that.
I will have to tebow and hope that doesn't happen.
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Old 04-18-2012, 12:45 PM   #94
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Old 04-18-2012, 12:46 PM   #95
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Quote:
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I hope you fall and break your tebown for posting that.
As soon as my knee is well I'm going to invent Tebow planking
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Old 04-18-2012, 12:48 PM   #96
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Quote:
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As soon as my knee is well I'm going to invent Tebow planking
Is that like putting a zero in the denominator?
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Old 04-18-2012, 12:49 PM   #97
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Quote:
Originally Posted by Senator View Post
Is that like putting a zero in the denominator?
I'll let you know in the year 1999
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Old 04-18-2012, 12:55 PM   #98
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Will read again.
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Old 04-18-2012, 12:59 PM   #99
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Quote:
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I will have to tebow and have faith that doesn't happen.

fixed.
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Old 04-18-2012, 01:35 PM   #100
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Quote:
Originally Posted by chase View Post
The knee is a gauge, and as you get faster it will happen less and less. I used to drag around every turn every lap, but now I just kinda tap knee every now and then. People that pivot on their tanks to get a knee down sadden me, as that style will eventually put them on the ground. But to address the hanging off comment, the lighter a rider is the more he needs off to get weight on the inside peg. A 150 lbs rider needs atleast half a cheek off the seat if not more, where 190 lbs and up gets half a cheek off at most. Hanging upper body off is not for dragging knee, though, the purpose of that is to get as much weight as possible to the inside of the centerline of the bike. By having your upper body inside and low, you stand the bike up more and are able to be more aggressive on the throttle on the exit, while adjustments midcorner are more forgiving as you now have much more room to work with lean angle wise.

Dragging knee doesn't make you fast, I've seen people win cmra championships on one set of kneepucks that looked almost new at the end of the season.

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Exactly what Keith Code told us in class. We even did a drill with it to practice trying to "stand up" the bike to get on the throttle sooner coming out of the turn.
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