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| esullivan |
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 esullivan Could Be A Chat Bot

Joined: 06 Mar 2012 Karma :   
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 Posted: 17:53 - 14 Apr 2014 Post subject: machine control course that I would recommend |
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I spent today on a windswept airfield in Bovington, doing a course on motorcycle control through i2i. Recommended, even if you think you have no issues with control. I did the first, basic course (Machine Control 1).
The instructor started the day by demonstrating pretty convincingly that the most unstable part of the motorcycle is the rider. We went through some exercises, culminating eventually with me standing up on the pegs, arms spread, turning right and left, while doing 30-35 down the landing strip. He showed us that cross winds have basically zero effect, even if we don't believe it, and demonstrating why we seem to get pushed to the side (hint: it's the rider).
We also did emergency stops, counter steering, slow control and swerving around hazards, but at a much higher speed and level than on the mod 1.
I didn't know what to expect. I was actually more interested in some of their higher level courses, and MC1 is a prerequisite, but I was pleasantly surprised. Even on slow control, which I do daily, I learned a thing or two. ____________________ Current: '14 VFR800X Test passed 31/10/12.
Previous: '12 NC700S, '11 CBF 125, '04 SH 125. |
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| FLV |
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 FLV Trackday Trickster

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| Rogerborg |
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 Rogerborg nimbA

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| Vincent |
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 Vincent Banned

Joined: 16 Oct 2006 Karma :    
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 Posted: 18:57 - 14 Apr 2014 Post subject: |
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If side winds have zero effect, why do they drill holes in the fairings at windy Philip Island?  ____________________ Space Is Deep |
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| esullivan |
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| esullivan |
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 esullivan Could Be A Chat Bot

Joined: 06 Mar 2012 Karma :   
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 Posted: 19:13 - 14 Apr 2014 Post subject: |
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On the wind, it was a good day for it because there was a strong, gusty crosswind. No one believed him when he said the wind has no effect.
He took a tyre and before rolling it down the runway, asked us which way it would eventually fall. All of us pointed in the direction of the wind. All of us were wrong. It actually fell into the wind.
The reason is physics -- an action causes an equal and opposite reaction. A motorcycle, with two spinning gyroscopes, will go straight as an arrow in all but hurricane-force winds. But it does react to the action of the wind by leaning into it. The rider, thinking the wheels are being swept out from under them, will counteract this by trying to straighten the bike up, leading to the bike seemingly get pushed over the road by the wind. ____________________ Current: '14 VFR800X Test passed 31/10/12.
Previous: '12 NC700S, '11 CBF 125, '04 SH 125. |
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| Pete. |
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 Pete. Super Spammer

Joined: 22 Aug 2006 Karma :     
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 Posted: 19:26 - 14 Apr 2014 Post subject: |
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So motorcycle have some magical properties that make them immune to Newton's third law? Don't think so. ____________________ a.k.a 'Geri'
132.9mph off and walked away. Gear is good, gear is good, gear is very very good  |
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| badgermat |
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 badgermat Two Stroke Sniffer

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| Islander |
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 Islander World Chat Champion

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 Islander World Chat Champion

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 Pete. Super Spammer

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| badgermat |
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 badgermat Two Stroke Sniffer

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| esullivan |
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| anthony_r6 |
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 anthony_r6 World Chat Champion

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| esullivan |
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 esullivan Could Be A Chat Bot

Joined: 06 Mar 2012 Karma :   
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 Posted: 06:22 - 15 Apr 2014 Post subject: |
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Another point I found interesting: A Frisbee is a gyroscope. You throw it (assume correctly) and it has a nice stable spin. Now, what happens if someone hits the Frisbee with their fingertips? It wobbles for a while before finding its balance again and straightening out. That's what happens with the front wheel sometimes, such as in a crosswind or even a tank slapper. The wheel will find its balance again on its own, almost instantly. Consider the youtube video with the tank slapper on the Isle of Man TT. After finally spitting off its rider (who is fighting the bars so much his arse and legs are flying through the air), the bike straightened up immediately (albeit briefly).
The main point he was making and reinforcing with the exercises was to let the gyroscope do its work -- have an extremely light touch on the bars. Don't fight them.
The other interesting aspect of gyroscopes is that they apply any force against them at 90 degrees off (some physics law again that I don't remember). To demo, he put a bicycle tyre in our hands with a long axle and asked us to turn it right and left. No problem. Now he spun the wheel and asked us to do it again. Instead of turning right and left, the wheel leans. It's hard to believe unless you try it, but your right hand is pushing forward and your left hand is pulling back, but the wheel is leaning to the right (and still pointing straight ahead) and you can't help it. Hence, counter steering. ____________________ Current: '14 VFR800X Test passed 31/10/12.
Previous: '12 NC700S, '11 CBF 125, '04 SH 125. |
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| esullivan |
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| Pete. |
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 Pete. Super Spammer

Joined: 22 Aug 2006 Karma :     
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 Posted: 06:46 - 15 Apr 2014 Post subject: |
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| badgermat wrote: | | Pete. wrote: |
But a gyroscope doesn't try to resist movement along (or perpendicular to) it's axis of rotation, as if the wind was blowing the bike sideways or the bike itself is moving forward. |
Agreed, though I would hope the tyres might provide some resistance to lateral movement.
I think the original point was that any lean is rider generated rather than wind generated. That was the way I read it, at least.
Whether that's true or not, I have no idea. But I suspect it's more a case that the increased sideways inertia of a gyroscope means that the wind has a considerably smaller effect on lean than rider input.
That said, I'm an ad-man not an engineer, so I officially have no idea what I'm talking about. I may not be alone in this, it is the internet, after all
bm |
Tyres will provide a lot of resistance to sideways movement, and yes, the lean is rider-generated because the wind is trying to fold the bike over with the tyre contact patch as the pivot. If the wind pushes the bike over then the bike will turn away from the wind so to counter it you have to lean in and provide an opposing force. ____________________ a.k.a 'Geri'
132.9mph off and walked away. Gear is good, gear is good, gear is very very good  |
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| Pete. |
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 Pete. Super Spammer

Joined: 22 Aug 2006 Karma :     
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 Posted: 06:52 - 15 Apr 2014 Post subject: |
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| esullivan wrote: | Another point I found interesting: A Frisbee is a gyroscope. You throw it (assume correctly) and it has a nice stable spin. Now, what happens if someone hits the Frisbee with their fingertips? It wobbles for a while before finding its balance again and straightening out. That's what happens with the front wheel sometimes, such as in a crosswind or even a tank slapper. The wheel will find its balance again on its own, almost instantly. Consider the youtube video with the tank slapper on the Isle of Man TT. After finally spitting off its rider (who is fighting the bars so much his arse and legs are flying through the air), the bike straightened up immediately (albeit briefly).
The main point he was making and reinforcing with the exercises was to let the gyroscope do its work -- have an extremely light touch on the bars. Don't fight them.
The other interesting aspect of gyroscopes is that they apply any force against them at 90 degrees off (some physics law again that I don't remember). To demo, he put a bicycle tyre in our hands with a long axle and asked us to turn it right and left. No problem. Now he spun the wheel and asked us to do it again. Instead of turning right and left, the wheel leans. It's hard to believe unless you try it, but your right hand is pushing forward and your left hand is pulling back, but the wheel is leaning to the right (and still pointing straight ahead) and you can't help it. Hence, counter steering. |
Whoa now - you (or rather he) is claiming that counter-steering is an effect of gyroscopic procession? A 10 kilo wheel being turned through perhaps 1 or 2 degrees of axis-change is going to roll a quarter of a ton of bike and rider when the larger rear wheel gyro is working to resist it? I ain't buying that - it might sound clever and plausible but it doesn't wash here. ____________________ a.k.a 'Geri'
132.9mph off and walked away. Gear is good, gear is good, gear is very very good  |
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| esullivan |
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| barrkel |
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 barrkel World Chat Champion
Joined: 30 Jul 2012 Karma :   
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 Posted: 10:31 - 15 Apr 2014 Post subject: |
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Re wind: a side wind will push the bike into a bit of a lean, the steering (through rake and trail) will turn into the lean to steer the bike back towards upright, but the bike's vector will have changed direction away from the wind. But it has to be a pretty strong wind to affect a bike (or tyre on its own) doing any speed. Also, the movement of a tyre on its own isn't like a bicycle - bicycles have a hinge between the two wheels.
To keep on a straight vector in strong wind you do need to apply some input. But it's not a lot, and I've never been blown around much, even when my GF feels like she's being blown around on her bike. I'm not sure why that is. It might be that she's gripping the bars too tightly.
If I'm travelling slowly enough for the wind to have a bigger effect, I tend to just countersteer to lean the bike into the wind like it's a big cushion, but being ready to countersteer back upright if it stops. Gusty winds require more focus, but that's about it. The wind is at its most annoying when I'm completely stopped and I need to switch feet on the ground to keep the bike balanced.
I'd like to try the experiment with the wheel on the long axle. ____________________ Bikes: S1000R, SH350; Exes: Vity 125, PS125, YBR125, ER6f, VFR800, Brutale 920, CB600F, SH300x4
Best road ever ridden: www.youtube.com/watch?v=s2MhNxUEYtQ |
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| tbourner |
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 tbourner World Chat Champion

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| map |
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 map Mr Calendar

Joined: 14 Jun 2004 Karma :     
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 Posted: 13:12 - 15 Apr 2014 Post subject: |
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Late to the party about crosswinds.
Apology if mentioned above (I skip read) I have found that the real problem lies with gusts of crosswind. A constant force can be countered, bugger all you can do if it's unpredictable.
A bit like overtaking lorries on the motorway. Their wake can be a bit unsettling. ____________________ ...and the whirlwind is in the thorn trees, it's hard for thee to kick against the pricks...
Gibbs, what did Duckie look like when he was younger?  |
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| Pete. |
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 Pete. Super Spammer

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| esullivan |
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 esullivan Could Be A Chat Bot

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| tbourner |
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 tbourner World Chat Champion

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Old Thread Alert!
The last post was made 11 years, 258 days ago. Instead of replying here, would creating a new thread be more useful? |
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