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  • How do you turn corners?

    What makes a unicycle change direction smoothly?

    A practical question:
    can anyone give me some tips to help me turn smoothly, particularly on hills please.

    An academic question:
    Where does the rotational force come from to make the wheel turn a corner please?

    Thanks.
    "I have to overcome a 'stress hill' when tightening the nuts, but once installed they sit in a 'stress valley'. "

    --Klaas Bil

  • #2
    Re: How do you turn corners?

    Originally posted by mike.hinson
    What makes a unicycle change direction smoothly?
    Mike,
    since you were putting emphasis on **smooth** turning, you may want to read the nicely phrased introduction to the theory of turning (as it related to spins, but you can ignore those paragraphs) by Ken Fuchs:
    http://www.unicycling.org/unicycling...mail/0427.html
    If you do not mind a more jerky turning style, a pure action/reaction turn from a standstill is another option. I am convinced that tire friction (and the relationship between friction and speed) plays a role here, but I will leave the details to the more theoretically inclined members of this group.

    Have fun,
    Fred

    Comment


    • #3
      Thanks for the link to Ken's excellent article.

      Am I to take it from the lack of additional replies that this subject is a bit of a mystery? I thought there would be some advanced maths to be explained, and lots of experiences shared.

      When I am cornering on my Uni I always feel like I am forcing it to do something it doesn't want to do & consequently my turns lack the control I would like. This is particularly in the context of Muni.

      Please help. Thanks.
      "I have to overcome a 'stress hill' when tightening the nuts, but once installed they sit in a 'stress valley'. "

      --Klaas Bil

      Comment


      • #4
        Originally posted by mike.hinson
        Am I to take it from the lack of additional replies that this subject is a bit of a mystery? I thought there would be some advanced maths to be explained, and lots of experiences shared.
        Countersteer.

        Do a Google search on "countersteer bicycle"
        Google
        Lots of stuff on the reason for and physics of countersteering.

        Unicycles need to countersteer too. That's how you force the uni to initiate a sharper turn.
        john_childs (att) hotmail (dott) com
        Team Never Wash Your Muni
        My Gallery :: Unicycling Bookmark List :: World Clock

        Comment


        • #5
          There are two basic ways to turn a unicyle: the gradual curve, as in following the curve of a road or path, and the sudden sharp turn through 90 or 180 degrees (or more) almost on the spot. (This excludes hopping and turning and all that clever stuff.)

          For the gradual turn, the unicycle leans in the general direction you want to turn, just like a bicycle or motorcycle. You need to keep the speed up. Long constant radius turns require concentration - the tighter the curve, the more concentration needed.

          For the sharp turn, it is easiest to turn to the right as the right pedal goes down, or to the left as the left pedal goes down.

          To see how this works, get off the uni, stand it up, and push down on the pedal with your hand. If you allow it to do so, the uni will lean slightly and turn sharply.

          Virtually all of the steering effect comes from the lean and the curvature of the wheel. It is nothing to do with hip snad thighs, gripping the seat or waving your arms, although these things can help in some circumstances. ;0)

          Back to counter steering, all you do is you use the pedal steering effect as for a 'sharp turn' to turn the uni a little way to the right, but with out allowing it to lean to the right. As your momentum is carrying you forwards, and the wheel is moved to the right, the effect is to tip the uni onto its left side quite quickly and smoothly, then you pedal round the curve as for a gentle curve.

          Of course, once you can do it, you should seldom think about it - just do it. So if you want one simple answer: you steer with the pedals, not the seat.
          My first novel, Bridge of Otherwhere, Michael Wilkinson, on Kindle. A tale of subtle magic, mystery, friendship and love. Tinyurl.com/Bridge-of-Otherwhere For US$ page: TinyURL.com/OtherwhereBridge

          Comment


          • #6
            Re: How do you turn corners?

            >Back to counter steering, all you do is you use the pedal steering
            >effect as for a 'sharp turn' to turn the uni a little way to the right,
            >but with out allowing it to lean to the right. As your momentum is
            >carrying you forwards, and the wheel is moved to the right, the effect
            >is to tip the uni onto its left side quite quickly and smoothly, then
            >you pedal round the curve as for a gentle curve.


            >Of course, once you can do it, you should seldom think about it - just
            >do it. So if you want one simple answer: you steer with the pedals, not
            >the seat.


            Pedals may have some part in steering a unicycle, but to say that
            unicycles are steered with the pedals is misleading.

            Almost all turning is initiated by a counter-steer. To counter-steer a
            unicycle, angular action / reaction is used. To turn left, a
            counter-steer to the right must first be done to establish a left lean.
            To counter-steer to the right, the upper body must twist to the left (the
            action) and in reaction the lower body must twist to the right which is
            the right counter-steer. With the left lean established it is now
            natural for the unicycle to circle to the left by just pedaling through
            it. To get out of the left turn at the desired turn angle, just do a
            counter-steer to the left to neutralize the lean and continue straight
            forward.

            The part the pedals play in counter-steering is they transmit some of
            the lower body twisting to the unicycle, but the seat also plays this
            role as well. Of course, the pedals have no role in the upper body
            twisting other than being a part of the reaction to that action.

            Sincerely,

            Ken Fuchs <kfuchs@winternet.com>

            Comment


            • #7
              of course, as ultimate wheel riders will tell us, the seat is not essential to the steering. I agree that all turns must start off with some good old Newtonian reaction against a mass - which means (in crude terms) you turn your lower body against the mass of your upper body and/or arms. I don't agree that counter steering is always used - in a turn 'on the spot' for example. However, counter steering is an essential component of steering when riding at any sort of speed.

              But back tot he steering with the pedals. It may or may not be literally true, but it is a useful way of 'feeling' what you are doing. Especially with sharp turns, or at low speed, timing the turn to coincide with the pedal going down is a useful skill.

              When riding, we don't consciously do physics calculations - we ride by feel. if the 'steering with the pedals' idea feels right and helps a new rider to develop the skill, surely that's all to the good.
              My first novel, Bridge of Otherwhere, Michael Wilkinson, on Kindle. A tale of subtle magic, mystery, friendship and love. Tinyurl.com/Bridge-of-Otherwhere For US$ page: TinyURL.com/OtherwhereBridge

              Comment


              • #8
                Re: How do you turn corners?

                On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
                <mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

                >An academic question:
                >Where does the rotational force come from to make the wheel turn a
                >corner please?


                I read this question as: from what does a rider derive a reaction
                force (moment) to turn the unicycle (and wheel) around its vertical
                axis. I'm not sure that Mike meant it this way, but anyway this
                question was not addressed yet. Countersteering is not an answer.
                Whether we do initial countersteering or not, there must be a first
                vertical twist but against what does a rider push or pull to bring it
                about? This question can be so puzzling that some people are tempted
                to say that unicycling is theoretically impossible.

                I think Mikefule may be closest to an answer by pointing at the
                pedals. If a rider rides relaxed and not in a corner/curved
                trajectory, the tyre contact point will actually describe a wiggly
                line. Every wiggle corresponds to one pedal stroke. On average, the
                contact point is below our centre of gravity. If then the rider would
                push one pedal a little harder, the corresponding wiggle will be
                larger (or maybe smaller but at least different), hence the tyre will
                deviate from the position under the centre of gravity, and here we
                have the initial lean that will drive the rider automatically into
                riding a curve.

                Klaas Bil

                If you had this signature, I have forged it.

                Comment


                • #9
                  Re: How do you turn corners?

                  On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
                  <mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

                  >An academic question:
                  >Where does the rotational force come from to make the wheel turn a
                  >corner please?


                  I read this question as: from what does a rider derive a reaction
                  force (moment) to turn the unicycle (and wheel) around its vertical
                  axis. I'm not sure that Mike meant it this way, but anyway this
                  question was not addressed yet. Countersteering is not an answer.
                  Whether we do initial countersteering or not, there must be a first
                  vertical twist but against what does a rider push or pull to bring it
                  about? This question can be so puzzling that some people are tempted
                  to say that unicycling is theoretically impossible.

                  I think Mikefule may be closest to an answer by pointing at the
                  pedals. If a rider rides relaxed and not in a corner/curved
                  trajectory, the tyre contact point will actually describe a wiggly
                  line. Every wiggle corresponds to one pedal stroke. On average, the
                  contact point is below our centre of gravity. If then the rider would
                  push one pedal a little harder, the corresponding wiggle will be
                  larger (or maybe smaller but at least different), hence the tyre will
                  deviate from the position under the centre of gravity, and here we
                  have the initial lean that will drive the rider automatically into
                  riding a curve.

                  Klaas Bil

                  If you had this signature, I have forged it.

                  Comment


                  • #10
                    Re: How do you turn corners?

                    On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
                    <mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

                    >An academic question:
                    >Where does the rotational force come from to make the wheel turn a
                    >corner please?


                    I read this question as: from what does a rider derive a reaction
                    force (moment) to turn the unicycle (and wheel) around its vertical
                    axis. I'm not sure that Mike meant it this way, but anyway this
                    question was not addressed yet. Countersteering is not an answer.
                    Whether we do initial countersteering or not, there must be a first
                    vertical twist but against what does a rider push or pull to bring it
                    about? This question can be so puzzling that some people are tempted
                    to say that unicycling is theoretically impossible.

                    I think Mikefule may be closest to an answer by pointing at the
                    pedals. If a rider rides relaxed and not in a corner/curved
                    trajectory, the tyre contact point will actually describe a wiggly
                    line. Every wiggle corresponds to one pedal stroke. On average, the
                    contact point is below our centre of gravity. If then the rider would
                    push one pedal a little harder, the corresponding wiggle will be
                    larger (or maybe smaller but at least different), hence the tyre will
                    deviate from the position under the centre of gravity, and here we
                    have the initial lean that will drive the rider automatically into
                    riding a curve.

                    Klaas Bil

                    If you had this signature, I have forged it.

                    Comment


                    • #11
                      Re: How do you turn corners?

                      On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
                      <mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

                      >An academic question:
                      >Where does the rotational force come from to make the wheel turn a
                      >corner please?


                      I read this question as: from what does a rider derive a reaction
                      force (moment) to turn the unicycle (and wheel) around its vertical
                      axis. I'm not sure that Mike meant it this way, but anyway this
                      question was not addressed yet. Countersteering is not an answer.
                      Whether we do initial countersteering or not, there must be a first
                      vertical twist but against what does a rider push or pull to bring it
                      about? This question can be so puzzling that some people are tempted
                      to say that unicycling is theoretically impossible.

                      I think Mikefule may be closest to an answer by pointing at the
                      pedals. If a rider rides relaxed and not in a corner/curved
                      trajectory, the tyre contact point will actually describe a wiggly
                      line. Every wiggle corresponds to one pedal stroke. On average, the
                      contact point is below our centre of gravity. If then the rider would
                      push one pedal a little harder, the corresponding wiggle will be
                      larger (or maybe smaller but at least different), hence the tyre will
                      deviate from the position under the centre of gravity, and here we
                      have the initial lean that will drive the rider automatically into
                      riding a curve.

                      Klaas Bil

                      If you had this signature, I have forged it.

                      Comment


                      • #12
                        Re: How do you turn corners?

                        On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
                        <mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

                        >An academic question:
                        >Where does the rotational force come from to make the wheel turn a
                        >corner please?


                        I read this question as: from what does a rider derive a reaction
                        force (moment) to turn the unicycle (and wheel) around its vertical
                        axis. I'm not sure that Mike meant it this way, but anyway this
                        question was not addressed yet. Countersteering is not an answer.
                        Whether we do initial countersteering or not, there must be a first
                        vertical twist but against what does a rider push or pull to bring it
                        about? This question can be so puzzling that some people are tempted
                        to say that unicycling is theoretically impossible.

                        I think Mikefule may be closest to an answer by pointing at the
                        pedals. If a rider rides relaxed and not in a corner/curved
                        trajectory, the tyre contact point will actually describe a wiggly
                        line. Every wiggle corresponds to one pedal stroke. On average, the
                        contact point is below our centre of gravity. If then the rider would
                        push one pedal a little harder, the corresponding wiggle will be
                        larger (or maybe smaller but at least different), hence the tyre will
                        deviate from the position under the centre of gravity, and here we
                        have the initial lean that will drive the rider automatically into
                        riding a curve.

                        Klaas Bil

                        If you had this signature, I have forged it.

                        Comment


                        • #13
                          Re: How do you turn corners?

                          On Mon, 30 Sep 2002 03:25:18 -0500, mike.hinson
                          <mike.hinson.bsb8m@timelimit.unicyclist.com> wrote:

                          >An academic question:
                          >Where does the rotational force come from to make the wheel turn a
                          >corner please?


                          I read this question as: from what does a rider derive a reaction
                          force (moment) to turn the unicycle (and wheel) around its vertical
                          axis. I'm not sure that Mike meant it this way, but anyway this
                          question was not addressed yet. Countersteering is not an answer.
                          Whether we do initial countersteering or not, there must be a first
                          vertical twist but against what does a rider push or pull to bring it
                          about? This question can be so puzzling that some people are tempted
                          to say that unicycling is theoretically impossible.

                          I think Mikefule may be closest to an answer by pointing at the
                          pedals. If a rider rides relaxed and not in a corner/curved
                          trajectory, the tyre contact point will actually describe a wiggly
                          line. Every wiggle corresponds to one pedal stroke. On average, the
                          contact point is below our centre of gravity. If then the rider would
                          push one pedal a little harder, the corresponding wiggle will be
                          larger (or maybe smaller but at least different), hence the tyre will
                          deviate from the position under the centre of gravity, and here we
                          have the initial lean that will drive the rider automatically into
                          riding a curve.

                          Klaas Bil

                          If you had this signature, I have forged it.

                          Comment


                          • #14
                            six times klaas!
                            a new record?
                            whatever caused this is causing more of it at the moment


                            mike, i'm curious, why the need for 'smoother' turns?
                            Three short Gs and a long E-flat™ - UniHoki
                            If I'm Murdered, Don't Execute My Killer.
                            harper
                            MikeFule Seager BluntRM
                            NAMASTE!
                            Dave

                            Comment


                            • #15
                              > I read this question as: from what does a rider derive a reaction
                              > force (moment) to turn the unicycle (and wheel) around its
                              > vertical axis. I'm not sure that Mike meant it this way, but
                              > anyway this question was not addressed yet.

                              All answers are interesting & lead to further understanding, I am also trying to understand where the force comes from to _continue_ turning the unicycle (and wheel & unicyclist) around its vertical axis as the unicycle continues to be ridden around a curve.

                              /\/\
                              "I have to overcome a 'stress hill' when tightening the nuts, but once installed they sit in a 'stress valley'. "

                              --Klaas Bil

                              Comment

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