Lost my cycling ability, back to the beginning.

Discussion in 'Cycling Archive' started by Adam Lea, May 3, 2012.

  1. Adam Lea

    Adam Lea Guest

    One week in Florida in mid April, come back and find that suddenly
    cycling to work has become a huge slog, and it is not just the incessant
    wind and rain. Average speed going to work, a pathetic 11-11.5 mph this
    week. For comparison, when I first started cycling to work in spring
    2006 I averaged 11.5 mph on the same bike (different drivetrain) and a
    longer route. I'm hoping I'll get my cycling legs back soon.
     
    Adam Lea, May 3, 2012
    #1
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  2. Adam Lea

    PeterFox Guest

    As Frankie Howerd would say "fret ye not". My bike has been used as an extra
    clothes-horse for the last month. I'm getting worried that American tourists
    will start coming to have their photographs taken standing in front of this
    genuine icon of English heritage.

    The 'confusion-friction-disillusion' is in your legs but the 'spark' is in your
    head. The first will evaporate. Study evaporation and see how the pool stays
    until one day the last half-millimetre dries-out in minutes. (You know it will.)
     
    PeterFox, May 4, 2012
    #2
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  3. Adam Lea

    Rob Morley Guest

    A week off should see you quicker, not slower - there's something else
    going on, maybe jet-lag related?
     
    Rob Morley, May 4, 2012
    #3
  4. Heh, if I get my moving average as high as 11.5mph over a month I feel
    I'm doing well :) (11.9 first half of April, but 11.4 the second half.
    Only 11.3 so far in May).

    Hope you get back to normal and enjoying it soon!
     
    Eleanor Blair, May 4, 2012
    #4
  5. Adam Lea

    mrc7--urcm Guest

    In message <>
    You didn't notice any illness, perhaps flu like symptoms? Insect bites?
    Or other symptoms of lethargy in general?

    Mike
     
    mrc7--urcm, May 4, 2012
    #5
  6. Adam Lea

    Adam Lea Guest

    Yes I am generally tired, particularly in the morning, but that is
    normal for me.
     
    Adam Lea, May 4, 2012
    #6
  7. Adam Lea

    Adam Lea Guest

    Well I am only 34, and at my age am probably as fit as I am ever going
    to get, so I'm hoping I will get back into it soon.
     
    Adam Lea, May 4, 2012
    #7
  8. Adam Lea

    Adam Lea Guest

    One thought that springs to mind is that due to the Easter break and the
    Florida trip I did lose the daily orange from my diet for nearly three
    weeks. When I started eating oranges regularly a year or so ago I did
    notice a reduction in fatigue and an increase in endurance and recovery
    ability.
     
    Adam Lea, May 4, 2012
    #8
  9. Adam Lea

    OG Guest

    You'd be surprised how much difference a bit of wind can make. The
    Easterly winds we had recently made a huge difference to my speed.

    Oh, and it's not symmetric - losing 5mph on the outward journey into a
    headwind isn't balanced out by gaining 5mph with a tailwind on the
    return; put them together and your average speed is reduced.
     
    OG, May 5, 2012
    #9
  10. Adam Lea

    Rob Morley Guest

    That's it then - you've got Rocky Mountain spotted fever, Lyme disease,
    West Nile virus, St. Louis encephalitis ... dodgy place, Florida.
     
    Rob Morley, May 5, 2012
    #10
  11. Adam Lea

    Paul Rudin Guest

    Yes, and this isn't terribly well understood. It's essentially because
    air resistance goes with the square of speed.

    So in a still wind if you're cycling at, say 10mph, with no wind and the
    air resistance is x, then if the wind blows with a 5 mph headwind, you
    effectively have 15mph wind to deal with and so you have x * (1.5^2) =
    2.25x air resistance. But if you have a 5 mph tail wind then you have
    effectively 5 mph wind and so x * (0.5^2) = 0.25x air resistance.

    The average of the two (for an out and back route) is 1.25x; whereas if
    you'd had no wind to deal with the average would have been x.
     
    Paul Rudin, May 6, 2012
    #11
  12. Adam Lea

    OG Guest

    To be honest, that's not what I was referring to.

    I was making the point that 1 mile out at 5 mph followed by 1 mile home
    again at 15mph takes a longer time than 2 miles there and back at 10mph
    - hence the slower average speed.
    I can see what you're trying to say, but in your example the cyclist
    doesn't adjust his speed, which is still 10mph on the ground in both
    directions.

    Yes, in your case he uses more energy, but his average speed doesn't
    change.
     
    OG, May 6, 2012
    #12
  13. Adam Lea

    Clive George Guest

    No oranges in Florida? :)
     
    Clive George, May 7, 2012
    #13
  14. Adam Lea

    Paul Rudin Guest

    That's true, but it's a strange way to look at it - at constant effort
    you won't gain the same speed with the tailwind as you lose with the
    headwind - so the 5mph and 15mph figures are not related just to the
    wind.

    That's right - it takes more energy to cover the distance in the same
    time with a wind, than without. Similarly, if you assume that you keep
    a constant power output then your average speed will be lower for the
    whole trip.
     
    Paul Rudin, May 7, 2012
    #14
  15. Adam Lea

    Adam Lea Guest

    I got out of the habit of eating them, these things happen after a
    sudden change of routine.
     
    Adam Lea, May 7, 2012
    #15
  16. Adam Lea

    Adam Lea Guest

    There was a big thread on urc which considered the case where a cyclist
    cycled at a constant effort for a fixed distance both in still air, and
    with a headwind. The conclusion was that the cyclist did the same amount
    of work in both cases as work done = force x distance, but I always had
    a problem with this as it seemed so counter-intuitive, after all,
    cycling at the same effort for longer in a headwind is surely
    dynamically equivalent to cycling for the same effort and time, but
    greater distance in the still air case?
     
    Adam Lea, May 7, 2012
    #16
  17. Adam Lea

    Clive George Guest

    My thread :)

    It wasn't constant effort, it was constant airspeed. Obviously what
    you're saying is right, so the power exerted in the headwind case needs
    to be lower. I think this is one of the main reasons people didn't get
    it - in real life you don't put less power in, so the theoretical
    situation didn't really match with people's experience.
     
    Clive George, May 7, 2012
    #17
  18. Adam Lea

    Danny Colyer Guest

    Most of the work done is in moving through the air. In the headwind
    case, the distance moved through the air is effectively greater.
     
    Danny Colyer, May 7, 2012
    #18
  19. Adam Lea

    Tom Gardner Guest

    That thread was wrong.

    There are two components which take energy to overcome: rolling
    resistance, and air resistance.

    To overcome air resistance:
    * energy consumption to make a journey, measured in J/km is
    proportional to the square of the velocity.
    * power consumption is proportional to the cube of the
    velocity - which is why it is more difficult to go at
    one more mph than it is to go at 1 mph

    To overcome rolling resistance:
    * the energy consumption does not depend on speed

    For a bicycle the transition from rolling-resistance-dominated
    cycling to air-resistance-dominated cycling takes place at
    a speed of about 12 km/h

    Source: http://www.inference.phy.cam.ac.uk/withouthotair/cA/page_260.shtml

    Read http://www.withouthotair.com/ to learn many things about
    energy - and to be able to cut through much guff about energy.
     
    Tom Gardner, May 7, 2012
    #19
  20. Adam Lea

    Paul Rudin Guest

    If by "constant effort" we mean the same power output then clearly the
    amount of energy expended is higher if you maintain that power output
    for a longer period.
     
    Paul Rudin, May 7, 2012
    #20
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