Dropping to flat

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Comments

  • Anonymous
    Anonymous Posts: 79,667
    Northwind wrote:
    There's some flats too. But a transition's just a flat at an angle :lol:
    a flat on an angle makes all the difference. Dropping to flat means that you go from the speed you were falling at, to zero, in an instant.
    Landing on a slope, or a transition, means that your falling speed only decreases, and doesn;t actually get halted.
  • Northwind
    Northwind Posts: 14,675
    Stopping instantly is just stopping slowly, only faster :wink:

    Just playing really, but some of those landings mean hitting a transition faster and harder than many of us will ever hit a flat, so the same things apply.
    Uncompromising extremist
  • Anonymous
    Anonymous Posts: 79,667
    No, they don't. The simple fact that there is a transition, makes all the difference.
    It's how ski jumpers can land without having their heelbones fired through the top of their heads.
  • Northwind
    Northwind Posts: 14,675
    Yes, but the forces are exactly the same, just reduced by the landing angle. Your relative rate of drop is lower (compared to the gradient of the ground) but landing a higher drop to a slope is much the same as landing a lower drop to a flat, it's the same gravity.
    Uncompromising extremist
  • Anonymous
    Anonymous Posts: 79,667
    Northwind wrote:
    Yes, but the forces are exactly the same, just reduced by the landing angle. Your relative rate of drop is lower (compared to the gradient of the ground) but landing a higher drop to a slope is much the same as landing a lower drop to a flat, it's the same gravity.
    It's the change in velocity that makes the difference. In fact, if you're traveling at a trajectory that exactly matches the slope, at the point you land, then you will feel no impact, because your velocity doesn't change.
    Think of it like landing on a half-pipe, if you get it right, you don't have to absorb the drop, only the G-out.
    It's simple mechanics.
  • Northwind
    Northwind Posts: 14,675
    Yes, and I did say exactly that. But I also said that if you're hitting a transition harder, it's the same as hitting a flat softer (ie, greater closing speed). It's just not the case that a transition landing is always softer than a flat landing.
    Uncompromising extremist
  • supersonic
    supersonic Posts: 82,708
    Well it does depend on the exact scenario.

    One reason DJers land nose first on steep down transitions is that the rear wheel usually follows - it guides the bike in, plus they can then pump off the slope.
    GT ZASKAR CARBON TEAM

    VOODOO CANZO

    Come and see me at https://www.facebook.com/biketyke/
  • Anonymous
    Anonymous Posts: 79,667
    Northwind wrote:
    if you're hitting a transition harder, it's the same as hitting a flat softer (ie, greater closing speed). It's just not the case that a transition landing is always softer than a flat landing.
    No, a transition landing is (as near as damn it) always softer. Your vertical speed drops to zero when landing to flat. It doesn't when landing on a transition. Anything over a handful of feet to flat is going to be harder than much much higher drops to transition.
    Adding horizontal speed into the equation does nothing to alleviate flat-landings, because your vertical speed will not be affected.
  • Northwind
    Northwind Posts: 14,675
    yeehaamcgee wrote:
    No, a transition landing is (as near as damn it) always softer.

    So dropping off a kerb is harder on your bike than this...

    http://i186.photobucket.com/albums/x106/pcinsc/Diablo5_10_08029e.jpg

    Riiiiight.
    Uncompromising extremist
  • Anonymous
    Anonymous Posts: 79,667
    Northwind wrote:
    So dropping off a kerb is harder on your bike than this...

    http://i186.photobucket.com/albums/x106/pcinsc/Diablo5_10_08029e.jpg

    Riiiiight.
    Oh for crying out loud...
    Read what I said again. :roll:
    fricking muppet.
  • supersonic
    supersonic Posts: 82,708
    I think he means for a certain vertical distance to touchdown lol
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    VOODOO CANZO

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  • Northwind
    Northwind Posts: 14,675
    I didn't just read what you said, I quoted it. Get a grip.

    Of course, it's simply wrong to say that your vertical speed drops to zero instantly when you land to flat, unless you're riding a rigid bike with solid tyres and you don't have any knees. This is what you're missing i think.

    While I'm quoting, this made I laff:
    yeehaamcgee wrote:
    In fact, if you're traveling at a trajectory that exactly matches the slope, at the point you land, then you will feel no impact, because your velocity doesn't change.

    In this scenario, you'll feel no impact because you'll never land :lol:
    Uncompromising extremist
  • Anonymous
    Anonymous Posts: 79,667
    let me say that again but this time I'll use italics to emphasise...
    if you're traveling at a trajectory that exactly matches the slope, at the point you land, then you will feel no impact, because your velocity doesn't change.

    So, imagine a transition, that changes severity. Now imagine the path you and your bike take. If your touchdown point is at an exact tangent to the transition, then you will feel no impact.
    It's the exact same principle as some step-up jumps, where the ground comes up after the take-off lip, and your bike meets terra firms with zero change in velocity.

    You seem to have an innate misunderstanding of the physics involved. Also, a blind refusal to be taught on the subject.

    As for
    Of course, it's simply wrong to say that your vertical speed drops to zero instantly when you land to flat, unless you're riding a rigid bike with solid tyres and you don't have any knees.
    Again. you misunderstand.
    The tyres being qsuashed etc are a result of you and your bike as one body, attempting to lose all it's velocity instantaneously. :roll:
  • The Northern Monkey
    The Northern Monkey Posts: 19,174
    Handbags anyone?! :lol:
    Santa Cruz Butcher
  • Anonymous
    Anonymous Posts: 79,667
    rather use my fists! :twisted:
  • Northwind
    Northwind Posts: 14,675
    yeehaamcgee wrote:
    So, imagine a transition, that changes severity. Now imagine the path you and your bike take. If your touchdown point is at an exact tangent to the transition, then you will feel no impact.

    OK, and what's the relevance of this exactly? Apart from trying to backpedal out of your previous example where you'd freefall forever and never land, over a transition that fell away at the same speed as you fell towards it, that is. Yes, it's theoretically possible to have a transition so perfect that the change of vertical velocity is absent- the ground "coming up to meet you" rather than you falling onto the ground. But the odds of it happening are so slim as to be effectively impossible, and you're trying to apply that ideal theoretical situation to every transition landing, which of course is nonsense.
    yeehaamcgee wrote:
    The tyres being qsuashed etc are a result of you and your bike as one body, attempting to lose all it's velocity instantaneously. :roll:

    Of course they are. Exactly the same as when the suspension compresses on a transition landing. What did I say that suggests otherwise? It's you that's trying to suggest that the two are practically different, not me. The key word here is "attempting"- before you stated that you stop instantly, now you're backing off from that, realising your mistake presumably? But missing, or ignoring, the point that in all landings the act of absorbing the impact and the duration of the impact is the same, only the amount of force caused by the reduced change of vertical velocity is different. You don't change vertical velocity any slower when you land to a slope, you just change less.

    Now, I'm a wee bit bored of this, but if you can post a response without saying anything patronising, flat out wrong, or insulting, maybe we can keep going ;)
    Uncompromising extremist
  • Anonymous
    Anonymous Posts: 79,667
    oh you know what? f*ck you. You're a dickhead, withg learning dificulties. I get it now.
  • SPIRO
    SPIRO Posts: 200
    Reckon its time the mods close this one before the mum insults start :roll:

    .
    S-Works Enduro 09'
  • Northwind
    Northwind Posts: 14,675
    What did you say about my mum? :lol:
    Uncompromising extremist
  • SPIRO
    SPIRO Posts: 200
    Northwind wrote:
    What did you say about my mum? :lol:

    She is a lovely women - what time do you want her back :wink:

    .
    S-Works Enduro 09'
  • biff55
    biff55 Posts: 1,404
    ^^above , lol , love it :lol:
  • Northwind
    Northwind Posts: 14,675
    Well, let her have a bit of a rest first, she's not as young as she used to be you know...
    Uncompromising extremist
  • _Ferret_
    _Ferret_ Posts: 660
    Interesting thread,
    I love the idea of a slope matching your trajectory - classic - sadly with such an idea you would either be on it or not - there is no point of landing! :lol:

    can't wait for next one like this - just don't pick up a physics book beforehand, you'll ruin all the laughs... :wink:
    Not really active
  • Anonymous
    Anonymous Posts: 79,667
    _Ferret_ wrote:
    Interesting thread,
    I love the idea of a slope matching your trajectory - classic - sadly with such an idea you would either be on it or not - there is no point of landing! :lol:
    Oh FFS. you too? a slope that matchces your trajectory at the point you land. Why is that so hard to grasp?
    Did none of you ever cover tangential geometry at school?

    Would you like me to draw some frigging diagrams explaining the theory :roll:
  • myopic
    myopic Posts: 692
    Entertaining guys! Think you may be talking at cross purposes?

    Yeeha, think you are talking about drops to vertical without forward momentum, ie just dropping off. Northwind, I think your drops to flat are ones on a trail where there is a lot of momentum and you therefore have forward motion?
    You don't need eyes to see, you need vision
  • Anonymous
    Anonymous Posts: 79,667
    forward motion makes no difference when dropping to flat. However, it does affect drops to a slope, because your forward speed, once in contact with the slope, allows you to continue traveling downwards as well as along.

    (i.e. being in motion on a slope means you're still losing altitude whereas being in motion on the flat gives no change in altitude)
  • myopic
    myopic Posts: 692
    yeehaamcgee wrote:
    forward motion makes no difference when dropping to flat. However, it does affect drops to a slope, because your forward speed, once in contact with the slope, allows you to continue traveling downwards as well as along.

    (i.e. being in motion on a slope means you're still losing altitude whereas being in motion on the flat gives no change in altitude)

    I'm sure this isn't right! If I was going to do a drop to flat (unless it was just off a kerb) - I would be more confident if I had a run up and some momentum. The higher it was, the more I would feel this was of benefit.
    You don't need eyes to see, you need vision
  • weeksy59
    weeksy59 Posts: 2,606
    yeehaamcgee wrote:

    Would you like me to draw some frigging diagrams explaining the theory :roll:


    Sure, use crayons and ideally some sticklebricks too.
    Salsa Spearfish 29er
    http://superdukeforum.forumatic.com/index.php
  • Anonymous
    Anonymous Posts: 79,667
    myopic wrote:
    yeehaamcgee wrote:
    forward motion makes no difference when dropping to flat. However, it does affect drops to a slope, because your forward speed, once in contact with the slope, allows you to continue traveling downwards as well as along.

    (i.e. being in motion on a slope means you're still losing altitude whereas being in motion on the flat gives no change in altitude)

    I'm sure this isn't right! If I was going to do a drop to flat (unless it was just off a kerb) - I would be more confident if I had a run up and some momentum. The higher it was, the more I would feel this was of benefit.
    So go on.... explain how forward speed affects the downwards acceleration from gravity, and the loss of that downwards speed when you hit the ground.
  • weeksy59
    weeksy59 Posts: 2,606
    yeehaamcgee wrote:
    So go on.... explain how forward speed affects the downwards acceleration from gravity, and the loss of that downwards speed when you hit the ground.

    If speed and velocity wasn't a factor then bullets would just fall on the ground as soon as they leave the barrel of a gun.

    The speed/velocity decreases the ammount of effect grvity has, therefore making it appear to defy the gravitational laws.
    Salsa Spearfish 29er
    http://superdukeforum.forumatic.com/index.php

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