9/18    What makes a bike turn? The horizontal component of lift makes an
        airplane turn. Does that mean the horizontal component of weight
        shift in a bike makes it turn?
        \_ bike tires have a circular profile (when inflated). the strip
           of rubber running down the middle of the crown is the farthest
           from the center of the wheel (radius), while the edges of the
           crown the closest. when you "turn" a bike at speed, you are
           really leaning into the turn and riding a contact patch biased
           towards one of the edges. the rubber stripes at the inner and
           outer edges of this patch travel different distances
           (circumferences) for the same revolution, and this causes the turn.
                -jwang
        \_ Equal and opposite force.
        \_ It's the horizontal component of the friction on the front wheel.
           Weight points downward, and the horizontal component is zero.
           -- yuen
        \_ no, the horizontal component of lift on an airplane only makes it
           go sideways.  horizontal deflection of air from the tail only
           is what makes it yaw (turn).
           \_ WRONG. link:www.gleim.com/Aviation/howtheyfly.html
                \_ quite simply, that page is confusing at best, and
                   technically wrong at worst.  You can turn a plane without
                   banking it  (its called a 'slipping turn'?).  The rudder
                   controls the 'turning' part, the yaw, which is even
                   mentioned on that page.   that Gleim page is  more of
                   an instructional one that tries to simplify things.

        \_ Bunch of dumb asses!  You turn the steering wheel, so it turns!
                \_ Haven't you guys ever seen the experiment where you hold
                        a spinning bicycle tire in your hand and try to turn
                        it along an axis perpendicular to the one about which
                        it is spinning?  I can't really explain it, but I
                        believe this is related to why a bike turns if you
                        lean over.  If the bike was moving, but the wheels
                        were not spinning (for example if you were sliding on
                        ice), then you would fall over instead of turn if you
                        lean.  It's conservation of angular momentum or
                        something.
                        lean.  It's conservation of angular momentum.  When
                        you lean, you change the angular momentum vector.  To
                        conserve angular momentum, the bike changes direction.