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Something I'd Love To See


faffi
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I guess this should be done by an instructor ideally, but this is what I'd like to see:

 

Riding in a circle, to avoid influence by quick-flick and other inputs that comes with a change of direction, I'd like to see a snapshot directly head-on of a rider going at exactly the same speed

- leaning out somewhat

- sitting bolt upright in line with the machine

- hanging off, but torso upright

- hanging off, torso low against the tank

- hanging off to the extreme, like Elias, for instance

 

Why? Because it would show what impact various riding positions have on how far the bike must lean over. The speed should, I reckon, be set so that the bike is decking out a little with the rider leaning out. Having the same rider do this should give a better indication than what I have seen from graphic descriptions elsewhere. It will also show just how valuable hanging off is, especially around long sweepers, I presume.

 

But perhaps I'm just weird and the only one to think this way :unsure:

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I guess this should be done by an instructor ideally, but this is what I'd like to see:

 

Riding in a circle, to avoid influence by quick-flick and other inputs that comes with a change of direction, I'd like to see a snapshot directly head-on of a rider going at exactly the same speed

- leaning out somewhat

- sitting bolt upright in line with the machine

- hanging off, but torso upright

- hanging off, torso low against the tank

- hanging off to the extreme, like Elias, for instance

 

Why? Because it would show what impact various riding positions have on how far the bike must lean over. The speed should, I reckon, be set so that the bike is decking out a little with the rider leaning out. Having the same rider do this should give a better indication than what I have seen from graphic descriptions elsewhere. It will also show just how valuable hanging off is, especially around long sweepers, I presume.

 

But perhaps I'm just weird and the only one to think this way :unsure:

There was a mag scan posted here detailing this pretty much in detail not so long time ago (this year I think). I think I have it on my desktop somewhere. Stay tuned...

 

Kai

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Thanks, Kai!

 

However, these 5 shots cannot have been taken at the same speed, I reckon. If you compare picture 1, 4 and 5, you see that #1 and #4 have the same lean angle, whereas #1 and #5 have similar riding positions.

 

It's surprising how little effect hanging out has. Even more surprising is how much hanging off in #3 helps, although this rider hangs off pretty far. He also seems to be more upright than what I've seen suggested here in just about every image; nothing much "looking at the mirror" here. Regardless - saving 13 degrees from hanging off seems, to me, a bit unrealistic. However, if they were shot at the same speed during steady cornering, I have to accept the evidence ;)

 

Taking this a bit further, the bloke leaning over 52 degrees is already going well over 1 G. And if we accept that hanging off gives 52 degrees combined with the bike leaned over 39 degrees, then the GP riders leaning the bike over 60 degrees must have a combined centripedal force of, well, A LOT. 60 degrees off vertical is already 2 G, and then add the benefit of hanging off and a MotoGP bike should be able to corner about 1.5 times as fast as a Porche or Ferrari street car.

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Hey Eirik, I reckon that's something you could try yourself... I have no problem believing that body position would have such a dramatic effect on lean angle. The rider is the upper half of the motorcycle - that's alot of weight that can be placed in various positions, so it logically follows that dramatically different body positions would have dramatically different effects on the bike.

 

I'm also interested to know more about how you got those figures for 52 degrees lean equalling 1G? Are these taken for an engineering or physics type of aspect? (As in what's 'possible', or are they actual measurements that have been taken?) I was reading Performance Bikes magazine recently and they have a guy who goes on all the bikes tests with datalogging gear. They said that effective braking was equal to about 1G. Maybe I don't quite understand if they're talking about typical braking on the street or track, but I can say that based on my own experience of track riding that I can't see how it's possible to carry the same sort of forces in a corner as are possible under heavy braking. Or maybe I'm wrong, or on the completely wrong track. But those figures got my attention.

 

The Nissan GT-R has a gauge that measures g-force, if I remember correctly it can achieve about 1.5g (I am fairly certain that it was not able to corner at anything near 2g). As much of a bike fan that I am, I have to admit that cars are capable of much higher cornering forces and corner speeds than a motorcycle.

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52 degrees is more than one G -one G = 45 degrees combined. Cars like the Dodge Viper, IIRC, is less than one G. It seems that 1 G is just about the limit for street cars, although I'm not very much into cars. If the Nissan can manage 1.5G it would mean that it's either in a class of its own or I haven't kept up ;)

 

I don't think I'd be a good example to use as I do not master hanging off very well and I also do not have a machine that can lean off to such a degree.

 

Why I'm sceptical that hanging off can give you 13 "free" degrees? Well, Hailwood won races long after hanging off became the norm, and he was always in line with the bike. Giving up that much cornering speed should prevent that. And if you look at the 125 racers, where the rider consist of about half the combined weight and hence hanging off should help more than on a comperatively heavy streetbike, the amount the bike is leaning doesn't change when they sit up on the seat, even if they do so when leaned over. I'm not debating that hanging off have an effect, I'm just stunned that it could have such a pronounced effect.

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I'm also interested to know more about how you got those figures for 52 degrees lean equalling 1G? Are these taken for an engineering or physics type of aspect?

 

http://www.motorcyclistonline.com/newsandupdates/122_0911_leaning_the_bike/index.html

 

 

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Cheers for that link - very interesting!

So 60 degrees would equal nearly 2g... that is getting fairly phenomenal!

Well there ya go, I learnt something new and found another goal - to join the 1g cornering club! biggrin.gif

 

(I still have niggling questions in the back of my mind as to whether nearly 2g would actually be measured if some data acquisition gear was attached to a bike. That figure is kinda massive, still blowing my mind...)

 

Now that I think about it more, it seems that I was confusing 'g' as a measure of available traction. But I guess that's not the whole story...

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Now that I think about it more, it seems that I was confusing 'g' as a measure of available traction. But I guess that's not the whole story...

'g' is the (specific) gravitational acceleration of the planet Earth or pull, if you like. It varies a little depending on where on the planet you are, but it's roughly 9.82 m/s^2.

This means that if we didn't have resitance from air drag etc, a ball dropped from some height would accelerate to a speed of 9.8 m/sec after 1 second, and 39.28 m/sec after one more second - that's 141.4kmph or 88 mph!

 

Imagine if we had NO gravitation and therefore no traction - we would move like in space, in a direct line until we fired a rocket-like engine in order to change direction.

So while gravitation is not only what keeps us to the ground, but it also determines how much traction we have - and although "gravity sucks", it's not a bad thing after all :)

 

Kai

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Gravity sucks? Nah I wouldn't say that, don't know what I'd do without it!

 

But what I meant was the difference in effective weight between different bikes & riders, cars etc. For example a GT-R at 1.3g would need enough traction to hold 2,262kg, a bike at 1.3g only needs enough traction to hold, say, 351kg. But the proportional amount of tyre contact patch is probably much greater for the GT-R, what I mean is it probably requires more than 6.4x the contact patch the bike has. What's my point...? I dunno - just trying to sort this out in my head. laugh.gif

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