Probability and consequence of slipping

Discussion in 'Cycling Equipment' started by Ivar Hesselager, Jul 19, 2004.

  1. I am preparing for the Oetztahler Radmarathon in Tyrol in late August and
    will prepare my bike and myself for the possibility of having to ride down
    the Alps in the cold rain. I could use some advice from exprienced mountain
    riders or bicycle scientists. I have planned to bring with me, as a spare
    tire, one Conti GP 4 Seasons, which is supposed to have a much better grip
    in cold and rainy weather than the GP 3000, that I normally use.
    Now granted, that I have only one GP 4 Seasons tire with me, where should I
    mount the tire with the better grip: Front or rear?

    I am not attempting any speed record, just want to make it through wihtin
    the time limit. But I am rather old and heavy for the climbing of 5.500 m
    during the day. So I could can sure use the weiht advantage going downhill -
    without having to ride too "courageously".

    My consideration - not based on experience - is that though front as well as
    back wheel can slip - it does not have the same probability and not the same
    consequence.

    Back wheel slip is more probable (I routinely brake the back wheel first)

    Back wheel slip during braking can be saved by releasing the brake quickly
    (my experience)

    Front wheel carries the bigger part of the load on steep downhill turns

    Front wheel slip will more often result in a fall

    Front wheel slip will make a quicker and harder fall


    Logically I need data for the formula of risk: Probability times
    consequence. But the best I can come up with is a feeling, that I should
    mount the tire with the better grip on the front wheel.




    Anyone with experience, knowledge or better analyzing skills?




    Regards

    Ivar of the Lowlands
     
    Tags:


  2. Ivar Hesselager wrote:
    > I am preparing for the Oetztahler Radmarathon in Tyrol in late August and
    > will prepare my bike and myself for the possibility of having to ride down
    > the Alps in the cold rain. I could use some advice from exprienced mountain
    > riders or bicycle scientists. I have planned to bring with me, as a spare
    > tire, one Conti GP 4 Seasons, which is supposed to have a much better grip
    > in cold and rainy weather than the GP 3000, that I normally use.
    > Now granted, that I have only one GP 4 Seasons tire with me, where should I
    > mount the tire with the better grip: Front or rear?
    >
    > I am not attempting any speed record, just want to make it through wihtin
    > the time limit. But I am rather old and heavy for the climbing of 5.500 m
    > during the day. So I could can sure use the weiht advantage going downhill -
    > without having to ride too "courageously".
    >
    > My consideration - not based on experience - is that though front as well as
    > back wheel can slip - it does not have the same probability and not the same
    > consequence.
    >
    > Back wheel slip is more probable (I routinely brake the back wheel first)


    This is not the best procedure. For most conditions, you're better off
    using the front brake by itself.

    See: http://sheldonbrown.com/brakturn

    > Back wheel slip during braking can be saved by releasing the brake quickly
    > (my experience)
    >
    > Front wheel carries the bigger part of the load on steep downhill turns
    >
    > Front wheel slip will more often result in a fall
    >
    > Front wheel slip will make a quicker and harder fall


    Yes. If you will be using two tires with different traction qualities,
    the one with better traction always should be on the front wheel

    Sheldon "One Brake At A Time" Brown
    +-----------------------------------------------------------+
    | It is by riding a bicycle that you learn the contours |
    | of a country best, since you have to sweat up the hills |
    | and coast down them. |
    | Thus you remember them as they actually are, while in a |
    | motor car only a high hill impresses you, and you have |
    | no such accurate remembrance of country you have driven |
    | through as you gain by riding a bicycle. |
    | -- Ernest Hemingway, By-Line |
    +-----------------------------------------------------------+
    Harris Cyclery, West Newton, Massachusetts
    Phone 617-244-9772 FAX 617-244-1041
    http://harriscyclery.com
    Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
  3. "Sheldon Brown" wrote:
    For most conditions, you're better off
    > using the front brake by itself.


    I have read the well argued articles about breaking techniques by Sheldon
    Brown and Jobst Brandt - and though I am impressed with their detailed
    insight, I feel confirmed that braking rear wheel first is a good habbit.
    I am convinced though, that the habit in my case originates from the
    aparantly worldwide myth (which was prevailing wisdom in the 80's) that
    braking frontwheel first, is likely to throw you head on over the handlebar.

    I am sure Brown&Brandt are right, that in most cases it is unnesseray to
    brake back wheel first. But it follows from that, that it IS necessary in
    some other situations - when front wheel traction is low, or - and this is
    important - lower than you expect.

    It is logical, that you don't know when the traction is lower than you
    expect, so you don't (allways) know when you should brake back wheel first.
    And since in worst case it is unnecesary but harmless to brake back wheel
    first, and in other cases - that you can't predict - it is necesary to
    brake backwheel first, you are in my opinion still better off making it a
    habit to brake back wheel first.

    Roads in my part of the world get slippery from traffic film, rain, sand,
    fallen leaves, ice etc. And a back wheel slide , which can be recovered,
    can be considered as an early warning much preferable to a frontwheel slide,
    that will probably bring you down. Furthermore the (limited) deceleration
    of the back wheel braking, may just be sufficient to prevent the front wheel
    from sliding when the front brake is applied.
    So braking backwheel a split second before frontwheel is still the safer
    procedure - and a good habit.




    Thanks Sheldon for your brief and precise stating, that the tire with the
    better traction goes on the frontwheel. No further explanation is needed.


    Ivar of Denmark

    ------------------------------------


    The word is round (I think Christobal Columbus said that)

    The bike will get you aorund (I said that)









    > See: http://sheldonbrown.com/brakturn
    >
    > > Back wheel slip during braking can be saved by releasing the brake

    quickly
    > > (my experience)
    > >
    > > Front wheel carries the bigger part of the load on steep downhill turns
    > >
    > > Front wheel slip will more often result in a fall
    > >
    > > Front wheel slip will make a quicker and harder fall

    >
    > Yes. If you will be using two tires with different traction qualities,
    > the one with better traction always should be on the front wheel
    >
    > Sheldon "One Brake At A Time" Brown
    > +-----------------------------------------------------------+
    > | It is by riding a bicycle that you learn the contours |
    > | of a country best, since you have to sweat up the hills |
    > | and coast down them. |
    > | Thus you remember them as they actually are, while in a |
    > | motor car only a high hill impresses you, and you have |
    > | no such accurate remembrance of country you have driven |
    > | through as you gain by riding a bicycle. |
    > | -- Ernest Hemingway, By-Line |
    > +-----------------------------------------------------------+
    > Harris Cyclery, West Newton, Massachusetts
    > Phone 617-244-9772 FAX 617-244-1041
    > http://harriscyclery.com
    > Hard-to-find parts shipped Worldwide
    > http://captainbike.com http://sheldonbrown.com
    >
     
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