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Re: [NYCKickScooters] Re: Micro Black - any thoughts?

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  • Michael Y. Knackerson
    Masked (do you have a real name, btw?), Using your short 10 mile ride, you wrote that it would be 5,280 kicks, but the extra energy needed to scoot with a Roma
    Message 1 of 20 , Mar 15, 2011
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      Masked (do you have a real name, btw?),

      Using your short 10 mile ride, you wrote that it would be 5,280 kicks, but the extra energy needed to scoot with a Roma is comparable to climbing 5 floors of stairs.

      So, let's say that a flight has 10 steps, so that's 50 steps for 5 flights.  I also think that a simple step takes much less energy than a kick, but just to keep it simple, lets say that a step equals a kick, so, those 50 extra steps divided by 5,280 kicks comes to 0.0094 or roughly 0.9% of the total kicks required.  So, by your calculations, going 10 miles translates to less than 1% more energy expenditure on a Roma vs. an MG.  

      My gut feeling is that the average person is not going to notice an iota of difference in energy expenditure and to me, the difference in deck elevation is essentially comparable to the proverbial flea on the elephant's butt :-).  Ah, but remember, you wrote that one can kick more efficiently with the narrow deck of the Roma, which seems to me would far outweigh the extra energy requirement of the 1/8 inch higher deck, considering that there are 99% more kicks of the more efficient type as compared to your MG, where you have to widen your kick stance.  Heck, I still think that the measly extra 1% of energy needed is relatively insignificant.

      As for comparing the Roma to the Micro, at 25 flights, just scale up by a factor of 5, so that would be less than 5% of extra energy and aside from the much better "exercise", you could consider it my "penalty" for being able to ride the Roma comfortably with both feet on the deck for 10 miles (when I'm not kicking, of course)!  Sorry, I'd rather coast when I can and admire the scenery as compared to constantly trying not to step on my own feet with the minimal deck space for 10 miles, again!

      Btw, when you get to your destination after scooting that 10 miles, the calorie intake of that frosty cold beer that you will gulp will far surpass any amount of extra energy expended to get there and any thoughts of how much extra energy you expended in the first place will be long forgotten, but I bet you'll still enjoy your beer!  

      Just keepin' it real, so happy scootin!

      Mikey




      From: maskedmarvelswat <maskedmarvelswat@...>
      To: NYCKickScooters@yahoogroups.com
      Sent: Tue, March 15, 2011 8:50:27 PM
      Subject: [NYCKickScooters] Re: Micro Black - any thoughts?

       

      Thanks for the pictures, Mikey! Yes, a difference of 1/8 of an inch in kick height does not sound (or look) like a big difference.

      But think about it this way. A kick height that is 1/8 of an inch higher means that I have to lift my own weight straight up by that much with EVERY kick. Actually, first I have to lower my weight by bending my knee that much further with every kick, which also takes energy. But to keep it simple, let's assume that energy is only expended after the kick when I straighten my support leg and thereby lift my body up.

      Let's assume that I kick once every 10 feet, which means I kick 528 times in a mile and 5280 times in my typical 10-mile ride. I weigh about 200 lbs (100 kg).

      So, in order to compensate for the higher kick height of Xootr Roma, I would have to spend extra energy that is equivalent to lifting a weight of 100 kg straight up by a distance of 1/8 inch * 5280. That's 660 inches = 16.8 meters. Expressed as joules, the amount of extra energy is about 16,800 J or 16.8 kJ.

      Did I do the math right?

      That's not a trivial amount of energy. Even if you weigh less than I, it's the same amount of energy you would need to climb 5 floors of stairs when the elevator is broken. Most people would be out of breath after that. Of course, if your goal is to burn as many calories as possible, it's not a bad thing. But if you want to scooter as effectively as possible, you may want to pick the scooter with the lowest possible kick height.

      The kick height on the Micro Black is 1/2 of an inch lower than that on the Xootr Mg and therefore 20/32 of an inch lower than that on the Xootr Roma. To go from Micro Black to Xootr Roma would require 5*16.8 kJ = 84 kJ of extra energy per 10 miles. Put in another way, that would be the same as climbing 25 floors of stairs up.

      --- In NYCKickScooters@yahoogroups.com, "Michael Y. Knackerson" <maknak@...> wrote:
      >
      > Masked,
      >
      >
      > Be careful what you wish for, because I just happen to have both a Roma as well
      > as a MG in my fleet of scooters, so taking them out, lining them up and snapping
      > a few pics should answer the mail for you and all other interested person. It
      > appears that the Roma deck is approximately 2 7/8 of an inch from the ground and
      > the MG deck is 2 3/4 inch, so we're talking about 1/8 of an inch difference. I
      > hardly think that amount is noticeable when kicking for any distance or length
      > of time. As they say, a picture is worth a thousand words, so see attached and
      > I've uploaded to the YHG photos as well, at:
      >
      > http://groups.yahoo.com/group/NYCKickScooters/photos/album/813739492/pic/list
      >
      > Mikey
      >


    • roybassist
      ... He signed some previous posts (#1041, for example) as John . ... I believe John is talking strictly about the amount of energy used by the standing
      Message 2 of 20 , Mar 16, 2011
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        --- In NYCKickScooters@yahoogroups.com, "Michael Y. Knackerson" <maknak@...> wrote:
        >
        > Masked (do you have a real name, btw?),
        >

        He signed some previous posts (#1041, for example) as "John".

        >
        > Using your short 10 mile ride, you wrote that it would be 5,280 kicks, but the
        > extra energy needed to scoot with a Roma is comparable to climbing 5 floors of
        > stairs.
        >
        > So, let's say that a flight has 10 steps, so that's 50 steps for 5 flights. I
        > also think that a simple step takes much less energy than a kick, but just to
        > keep it simple, lets say that a step equals a kick,

        I believe John is talking strictly about the amount of energy used by the standing (support) leg *against gravity* in lifting the rider's weight. You, as a mechanical engineer, know that in physics work is defined as the amount of energy transferred by a force acting through a distance. In comparing a step in a flight of stairs to an extra 1/8" of vertical movement when kicking a scooter for any one person, the force will be the same in each case: equal to the weight of the person. The distance, however is very different. There is no standard height for stair steps, but they typically range from 7" to around 10". Even if you consider the minimum height of a stair step, 7", that is 56 times more distance than 1/8". So the amount of work done against gravity in lifting your body up one step in a flight of stairs is at least 56 times the amount done in raising your body an additional 1/8". So in terms of work against gravity, rather than one step being equal to the incremental effort of an additional 1/8" per kick, it is more like one step equals at least 56 kicks.

        > so, those 50 extra steps
        > divided by 5,280 kicks comes to 0.0094 or roughly 0.9% of the total kicks
        > required. So, by your calculations, going 10 miles translates to less than 1%
        > more energy expenditure on a Roma vs. an MG.

        To determine how significant the additional 1/8" is, for any distance, there is a simpler way that doesn't require assumptions about steps. For each kick, the work done against gravity by the support leg is equal to the total kick height times the weight of the rider. The percent increase from the MG to the Roma would be (Weight x Roma height – Weight x MG height)/(Weight x MG height). Since the weight term is always the same for a given rider, it cancels out and you are left with (Roma height – MG height)/MG height, which works out to 0.045 or 4.5 percent. This is for each kick, regardless of distance. Whether that is significant or not is a subjective judgment.

        > As for comparing the Roma to the Micro, at 25 flights, just scale up by a factor
        > of 5, so that would be less than 5% of extra energy

        A similar calculation using the relative kick heights for the Micro Black versus the Roma yields about a 28 percent increase, and Micro Black versus MG is about 22 percent.

        Obviously, there are many other factors that influence the amount of exertion required of a rider, such as rolling resistance; but I think this shows why the kick height of a scooter matters.
      • maskedmarvelswat
        Thanks for your interesting posts, Mikey and Roy! I agree with Roy. Climbing stairs is definitely a more strenuous activity than scootering. I don t think many
        Message 3 of 20 , Mar 17, 2011
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          Thanks for your interesting posts, Mikey and Roy!

          I agree with Roy. Climbing stairs is definitely a more strenuous activity than scootering. I don't think many of us would be scootering if it were equally exhausting to climbing stairs. I can scooter for hours, but I can climb stairs for only a few minutes.

          Here's a link to a scientific article where they measured the energy cost of ascending stairs:
          http://journals.lww.com/acsm-msse/pages/articleviewer.aspx?year=2002&issue=04000&article=00021&type=abstract

          They found that the energy cost of climbing the vertical height of 15 cm is 0.11 nutritional calories (kcal) for a person with a body mass of 60 kg. Thus, the energy cost of climbing 16.8 meters is 12.3 calories. (This is more than the theoretical 16.8 kJ = 4 nutritional calories I calculated earlier probably because what I calculated was energy output rather than energy cost = calories burned).

          The energy cost of scootering has not been measured experimentally to my knowledge. But assuming that the energy cost of scootering is approximately similar to walking at a brisk pace (3.5 mph; 258 nutritional calories/hour), the energy cost of scootering for 90 minutes, which is the time it takes me to scooter 10 miles, would be 387 calories.

          Thus, an increase of 1/8 of an inch in the kick height (= the difference between Xootr Mg and Roma) would translate to a 3.2% increase in the total energy cost. The kick height difference between the Micro Black and Xootr Roma would translate to an increase of 16% in the total energy costs.

          I agree with Mikey that some or all of the kick heigh difference between Xootr Mg and Roma may be canceled out by the wider deck of the Xootr Mg, which has essentially the same effect as a higher kick height. I think the effect of a wider deck depends somewhat on the length of your legs (inseam). At least in theory, those with longer legs are affected less by a wider deck than those with shorter legs.

          As Roy noted, my name is John. I think it is generally a good idea to protect your identity online whenever possible and not to publish your full real name. My full name, address, and phone number are on file with Dorlene. I'd be happy to email that information to anyone else who is interested as well. I'm going to email it to Mikey.

          John


          --- In NYCKickScooters@yahoogroups.com, "roybassist" <roybassist@...> wrote:
          >
          > --- In NYCKickScooters@yahoogroups.com, "Michael Y. Knackerson" <maknak@> wrote:
          > >
          > > Masked (do you have a real name, btw?),
          > >
          >
          > He signed some previous posts (#1041, for example) as "John".
          >
          > >
          > > Using your short 10 mile ride, you wrote that it would be 5,280 kicks, but the
          > > extra energy needed to scoot with a Roma is comparable to climbing 5 floors of
          > > stairs.
          > >
          > > So, let's say that a flight has 10 steps, so that's 50 steps for 5 flights. I
          > > also think that a simple step takes much less energy than a kick, but just to
          > > keep it simple, lets say that a step equals a kick,
          >
          > I believe John is talking strictly about the amount of energy used by the standing (support) leg *against gravity* in lifting the rider's weight. You, as a mechanical engineer, know that in physics work is defined as the amount of energy transferred by a force acting through a distance. In comparing a step in a flight of stairs to an extra 1/8" of vertical movement when kicking a scooter for any one person, the force will be the same in each case: equal to the weight of the person. The distance, however is very different. There is no standard height for stair steps, but they typically range from 7" to around 10". Even if you consider the minimum height of a stair step, 7", that is 56 times more distance than 1/8". So the amount of work done against gravity in lifting your body up one step in a flight of stairs is at least 56 times the amount done in raising your body an additional 1/8". So in terms of work against gravity, rather than one step being equal to the incremental effort of an additional 1/8" per kick, it is more like one step equals at least 56 kicks.
          >
          > > so, those 50 extra steps
          > > divided by 5,280 kicks comes to 0.0094 or roughly 0.9% of the total kicks
          > > required. So, by your calculations, going 10 miles translates to less than 1%
          > > more energy expenditure on a Roma vs. an MG.
          >
          > To determine how significant the additional 1/8" is, for any distance, there is a simpler way that doesn't require assumptions about steps. For each kick, the work done against gravity by the support leg is equal to the total kick height times the weight of the rider. The percent increase from the MG to the Roma would be (Weight x Roma height – Weight x MG height)/(Weight x MG height). Since the weight term is always the same for a given rider, it cancels out and you are left with (Roma height – MG height)/MG height, which works out to 0.045 or 4.5 percent. This is for each kick, regardless of distance. Whether that is significant or not is a subjective judgment.
          >
          > > As for comparing the Roma to the Micro, at 25 flights, just scale up by a factor
          > > of 5, so that would be less than 5% of extra energy
          >
          > A similar calculation using the relative kick heights for the Micro Black versus the Roma yields about a 28 percent increase, and Micro Black versus MG is about 22 percent.
          >
          > Obviously, there are many other factors that influence the amount of exertion required of a rider, such as rolling resistance; but I think this shows why the kick height of a scooter matters.
          >
        • maskedmarvelswat
          I forgot to mention that I think Roy s calculations are very elegant and accurate, but apply only to the energy spent by the support leg, just like the
          Message 4 of 20 , Mar 17, 2011
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            I forgot to mention that I think Roy's calculations are very elegant and accurate, but apply only to the energy spent by the support leg, just like the calculations in my earlier post #1504.

            The kicking leg does not work as hard as the support leg, but there is some energy cost associated with kicking as well, particularly if you are using Roy's "swinging pendulum" technique. The energy spent for kicking does not depend on the kick height.
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