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Date: 02 Nov 2007 15:42:46
From: Ken Roberts
Subject: propulsive forces tacking to climb hill
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While "tacking" to climb up a steep hill, I found some moves different from
normal cycling to help me get up the hill easier: swinging my shoulders
sideways up the hill, and using my arms to "sweep" my wheels directly
sideways toward down the hill. It enabled me to survive a long steep hill --
and doing it made the climbing sorta fun.
By "tacking" I mean turning my bike diagonally off my overall direction of
forward motion, then turning my bike again to go diagonally toward the other
side, and repeating to make a sort of curved zig-zag path. Of course I would
only do this when I have lots of road-width available with no other vehicles
using it. Using a "tacking" path can make it easier to climb up a steep hill
by spreading a fixed vertical gain over a much longer horizontal distance --
effectively reducing the hill's steepness, and so reducing the minimum power
output required to climb up it with losing control or stopping.
The zig-zag path also offers some different opportunities to _add_ more
propulsive work and power for the climbing. I found this out when I wanted
to do this long steep climb on a rental bike that didn't have low gears.
There was supposed to be an exciting descent on the other side that I wanted
to try, but I knew I was going to have to "cheat" to get to the top without
lots of walking. It was a remote area on a mid-week day with little car
traffic, so I decided to try some "tacking". And that helped make it easier,
as expected.
In the midst of the climb I got the idea that I could take some burden off
my leg muscles by directly "throwing" the weight of my upper body up the
hill. While riding mostly sideways across the hill, just as I started my
turn to go the other way, I swung my shoulders sideways up the hill. And
that made it easier to pedal thru the turn -- which is the tough part of
tacking up a steep hill. This worked for me while pedaling either standing
or sitting. So I did those upper body move lots more. Then my abdominal
muscles got tired from doing all that the sideways "tossing" -- it's not
something I trained for. So I went back to simple pedaling, then did some
more sideways tossing again later.
With this new tool, now I can take on even steeper climbs, I thought. So the
next day I decided to try the east side of Colle dell'Agnello on the
Italy-France border. It's the third-highest paved mountain pass in Europe,
used in the Giro d'Italia recently, sustained steeper than Stelvio (and much
steeper than Alpe d'Huez), also an automated time-trial course. Until that
day it was unimaginable that I could survive climbing it on a rental bike
lacking ultra-low gears. I started early in the morning, very little
traffic, and when I reached the sustained steep part I started tacking
again, and some of the "sideways shoulder-tossing" move -- and then I
thought to try another move:
While pedaling sitting going diagonally across the road, just at the start
of the turn to go the other way, I pushed my hand down on the uphill end of
the handlebar, and pulled my hand up on the downhill end of the handlebar --
which pushed my wheels directly sideways in the direction diagonally down
the hill -- sort of "sweeping" the wheels under me from the uphill side to
the downhill side (thus toward the outside of the turn I was going into). It
definitely helped me get thru the zig-zag turn more easily. It felt really
different to be pushing the wheel directly sideways. And it was fun to play
with: different timing of the start and finish of the move relative to the
turn, mixing it with the "sideways shoulder toss", standing versus sitting,
tighter higher-frequency zig-zags. I was the first rider up to the pass, and
I felt so good I rode part of the way down the other side into France and
climbed back.
This second "wheels side-sweep" move is different from tilting the bike from
side while standing, because that purpose of that standing move is to add
more force thru the _legs_ pushing on the pedals and drivetrain to help the
wheels roll forward. This "wheels side-sweep" move also works while pedaling
sitting, and transmits force thru the frame and axles directly to the wheels
to push directly sideways, not thru the chain and cogs to roll forward. The
physics is more like _skating_ than normal bicycling.
On my descent I went by the other cylists climbing the "correct" way,
straight up the road in low pedaling frequency, and there was no doubt it my
mind that cheating with those strange moves was just more fun.
Ken
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Date: 03 Nov 2007 22:34:55
From: Bob
Subject: Re: propulsive forces tacking to climb hill
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On Nov 3, 7:57 pm, Tom Sherman <sunsetss0...@REMOVETHISyahoo.com >
wrote:
> landotter wrote:
> > On Nov 2, 11:32 am, "Leo Lichtman" <l.licht...@worldnet.att.net>
> > wrote:
> >> "Ken Roberts" wrote: While "tacking" to climb up a steep hill, I found some
>
> >> moves different from normal cycling to help me get up the hill easier:
> >> swinging my shoulders sideways up the hill, and using my arms to "sweep" my
> >> wheels directly sideways toward down the hill. (clip)
> >> ^^^^^^^^^^^^^^^^^^^
> >> I recently saw a guy going up a hill on a scooter doing something like this.
> >> This was not a normal scooter--it was V shaped, with one front wheel and two
> >> rear wheels, and he had one foot on each side of the V. He did not touch
> >> the ground with his feet at all, so the propulsion HAD to come from the way
> >> he was tacking and throwing his body weight back and forth.
>
> >http://www.razor-scooters.com/trikke-scooters/default.htm
>
> >http://youtube.com/watch?v=5hsEDgpI_h4
>
> And some people complain about recumbent trikes taking up too much width
> on the MUP! The riders of the Trikke are taking up about twice the width.
>
> --
> Tom Sherman - Holstein-Friesland Bovinia
> When did ignorance of biology become a "family value"?- Hide quoted text -
>
> - Show quoted text -
You realize of course that your statement is simply a variation on the
classic "I'm not as bad as so and so". Personally, I have no major
issue with trikes or even those four person pedal carriages they rent
down at Navy Pier. Some do yield the right of way to others. I just
wish they all did.
Regards,
Bob Hunt
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Date: 03 Nov 2007 08:51:43
From: Doc O'Leary
Subject: Re: propulsive forces tacking to climb hill
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In article <WzHWi.16$9N6.13@trnddc03 >,
"Ken Roberts" <iKen7Roberts7-nn7_no7s@yahoo7.com > wrote:
> By "tacking" I mean turning my bike diagonally off my overall direction of
> forward motion, then turning my bike again to go diagonally toward the other
> side, and repeating to make a sort of curved zig-zag path.
FYI, this is more often referred to as switchbacks. For the obvious
reason, see:
http://en.wikipedia.org/wiki/Hairpin_bend
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My personal UDP list: 127.0.0.1, 4ax.com, buzzardnews.com, googlegroups.com,
heapnode.com, localhost, ntli.net, teranews.com, vif.com, x-privat.org
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Date: 05 Nov 2007 01:15:56
From: Ken Roberts
Subject: Re: propulsive forces tacking to climb hill
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Doc O'Leary wrote
> http://en.wikipedia.org/wiki/Hairpin_bend
I did not see anything on that page which sounded like what I was doing with
my bike on those steep climbs.
"Tacking" is a possible cycling technique even if the road goes perfectly
straight up the hill. I can steer my bike thru a zig-zag path, even if the
road does not make any zig-zags. In fact I mostly did tacking moves only
when the road was _not_ in a curve.
My understanding is that "switchbacks" are when the road makes zig-zags;
"tacking" is when me and my bike make zig-zags.
Ken
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Date: 05 Nov 2007 07:52:43
From: Doc O'Leary
Subject: Re: propulsive forces tacking to climb hill
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In article <g9uXi.2249$b%1.1075@trnddc01 >,
"Ken Roberts" <iKen7Roberts7-nn7_no7s@yahoo7.com > wrote:
> Doc O'Leary wrote
> > http://en.wikipedia.org/wiki/Hairpin_bend
>
> I did not see anything on that page which sounded like what I was doing with
> my bike on those steep climbs.
Look again. You went back and forth while moving up a slope. That's a
switchback.
> My understanding is that "switchbacks" are when the road makes zig-zags;
> "tacking" is when me and my bike make zig-zags.
Your understanding is wrong. You are mistaking pavement for path. The
technique is the same regardless of the surface you're on. In fact, it
could even be necessary to ride switchbacks *on* a switchback road!
--
My personal UDP list: 127.0.0.1, 4ax.com, buzzardnews.com, googlegroups.com,
heapnode.com, localhost, ntli.net, teranews.com, vif.com, x-privat.org
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Date: 06 Nov 2007 00:33:14
From: Ken Roberts
Subject: Re: propulsive forces tacking to climb hill
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Doc O'Leary wrote
> The technique is the same regardless of the surface you're on.
Maybe that's true for your technique -- but it's not "the same" for mine.
The two propulsive techniques I described in my original post are much more
effective for adding net positive propulsive work when performed on a short
tight turn -- because of (a) Newton's Third Law about reactive force; and
(b) Force = Mass * Acceleration in a limited distance situation.
(a) In order for the muscular force and work of accelerating my
center-of-mass sideways relative to the bicycle wheels not to be _cancelled_
by the force of decelerating my center-of-mass on the other side, there
needs to be a change in the direction of the bicycle frame during the time
between the acceleration and the deceleration. Otherwise the "equal and
opposite" reactive force from deceleration will slow me and my bike down
just as much as my acceleration move speed me up. So for a given rolling
speed, the larger is the radius of curvature (and thus the smaller the
change in direction), the higher the percentage of the muscular work put
into my two techiques gets cancelled out -- self-cancelled.
(b) Since Work = Force * Distance, and the distance I can move my
center-of-mass sideways is strongly limited, the Work from each move depends
on the Force, and since Acceleration is proportional to Force in the case,
that means that getting more Work from each move requires reaching higher
relative sideways Velocity. Then since the Distance of sideways motion of my
body relative to the bicycle frame is strongly limited, then the Time
duration between the start and finish of the sideways move must be much
briefer. I cannot get the same of work from either of those moves by doing
the same distance, but slower.
So if my change of direction is made on a curve with the wider radius of a
typical road "switchback" or "hairpin", instead of my snappy little
tight-radius "tacking" turns, there are two cases:
* If I make one of my special sideways moves slowly so it starts with the
start of the road curve and finishes with the end of the road curve, then I
generate little work (according to (b));
* If I make my move very quickly somewhere in the midst of the road curve,
then much of its work is self-cancelling (according to (a)).
Size matters.
Intelligently controlling my own turns to achieve my own goal works much
better than having my turns dictated by a road designed for a different
goal.
Ken
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Date: 02 Nov 2007 13:57:11
From: landotter
Subject: Re: propulsive forces tacking to climb hill
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On Nov 2, 11:32 am, "Leo Lichtman" <l.licht...@worldnet.att.net >
wrote:
> "Ken Roberts" wrote: While "tacking" to climb up a steep hill, I found some
>
> moves different from normal cycling to help me get up the hill easier:
> swinging my shoulders sideways up the hill, and using my arms to "sweep" my
> wheels directly sideways toward down the hill. (clip)
> ^^^^^^^^^^^^^^^^^^^
> I recently saw a guy going up a hill on a scooter doing something like this.
> This was not a normal scooter--it was V shaped, with one front wheel and two
> rear wheels, and he had one foot on each side of the V. He did not touch
> the ground with his feet at all, so the propulsion HAD to come from the way
> he was tacking and throwing his body weight back and forth.
http://www.razor-scooters.com/trikke-scooters/default.htm
http://youtube.com/watch?v=5hsEDgpI_h4
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Date: 03 Nov 2007 19:57:19
From: Tom Sherman
Subject: Re: propulsive forces tacking to climb hill
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landotter wrote:
> On Nov 2, 11:32 am, "Leo Lichtman" <l.licht...@worldnet.att.net>
> wrote:
>> "Ken Roberts" wrote: While "tacking" to climb up a steep hill, I found some
>>
>> moves different from normal cycling to help me get up the hill easier:
>> swinging my shoulders sideways up the hill, and using my arms to "sweep" my
>> wheels directly sideways toward down the hill. (clip)
>> ^^^^^^^^^^^^^^^^^^^
>> I recently saw a guy going up a hill on a scooter doing something like this.
>> This was not a normal scooter--it was V shaped, with one front wheel and two
>> rear wheels, and he had one foot on each side of the V. He did not touch
>> the ground with his feet at all, so the propulsion HAD to come from the way
>> he was tacking and throwing his body weight back and forth.
>
> http://www.razor-scooters.com/trikke-scooters/default.htm
>
>
> http://youtube.com/watch?v=5hsEDgpI_h4
>
And some people complain about recumbent trikes taking up too much width
on the MUP! The riders of the Trikke are taking up about twice the width.
--
Tom Sherman - Holstein-Friesland Bovinia
When did ignorance of biology become a "family value"?
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Date: 03 Nov 2007 03:34:55
From: Ken Roberts
Subject: Re: propulsive forces tacking to climb hill
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landotter wrote
> http://www.razor-scooters.com/trikke-scooters/default.htm
> http://youtube.com/watch?v=5hsEDgpI_h4
That Trikke looks like a very creative device. Not very expensive. It's
tempting to try.
On the other hand, I've already worked thru the learning curve with inline
skates out on the roads, and I think they're more different from a
bicycle -- so they offer me a greater variety of experience.
. (On the Trikke Comparison Chart, it looks to me like somebody got confused
between percent grade and degrees, as a way to measure the steepness of a
hill-climb.)
Ken
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Date: 02 Nov 2007 16:32:05
From: Leo Lichtman
Subject: Re: propulsive forces tacking to climb hill
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"Ken Roberts" wrote: While "tacking" to climb up a steep hill, I found some
moves different from normal cycling to help me get up the hill easier:
swinging my shoulders sideways up the hill, and using my arms to "sweep" my
wheels directly sideways toward down the hill. (clip)
^^^^^^^^^^^^^^^^^^^
I recently saw a guy going up a hill on a scooter doing something like this.
This was not a normal scooter--it was V shaped, with one front wheel and two
rear wheels, and he had one foot on each side of the V. He did not touch
the ground with his feet at all, so the propulsion HAD to come from the way
he was tacking and throwing his body weight back and forth.
I haven't figured out why it works, and wouldn't have believed it if I
hadn't seen it. I rolled my window down and said, "You can't do that," and
he laughed.
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Date: 02 Nov 2007 19:12:22
From: Ken Roberts
Subject: Re: propulsive forces tacking to climb hill
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Leo Lichtman wrote
> I recently saw a guy going up a hill on a scooter doing something like
> this.
Strange things are out there. Probably there's a video of it somewhere.
Here's a video of guy propelling himself on one skate (on the flat) by
pushing it diagonally to one side and then the other.
http://www.youtube.com/watch?v=mMmDzY5f0gk
At first he does it with two skates on the ground, and it looks pretty
believable -- feels like "I could do that, too". Then around time 1:08 he
takes it to his limit.
I wonder if riding a bicycle on smooth flat pavement, if you could propel
yourself on a zig-zag path using only cleverly-timed sideways
shoulder-shifts and pulling up and down on the handlebars for wheel
side-force -- with no pedaling at all?
Ken
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Date: 02 Nov 2007 21:16:45
From:
Subject: Re: propulsive forces tacking to climb hill
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Ken Roberts writes:
>> I recently saw a guy going up a hill on a scooter doing something
>> like this.
> Strange things are out there. Probably there's a video of it
> somewhere.
> Here's a video of guy propelling himself on one skate (on the flat)
> by pushing it diagonally to one side and then the other.
http://www.youtube.com/watch?v=mMmDzY5f0gk
> At first he does it with two skates on the ground, and it looks
> pretty believable -- feels like "I could do that, too". Then around
> time 1:08 he takes it to his limit.
> I wonder if riding a bicycle on smooth flat pavement, if you could
> propel yourself on a zig-zag path using only cleverly-timed sideways
> shoulder-shifts and pulling up and down on the handlebars for wheel
> side-force -- with no pedaling at all?
Try it. You'll find just yoyoing the steering of your bicycle from
side to side will propel it forward... slowly. Use a standing start.
Jobst Brandt
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Date: 03 Nov 2007 03:27:16
From: Ken Roberts
Subject: Re: propulsive forces tacking to climb hill
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jobst.brandt@stanfordalumni.org wrote
> Try it. You'll find just yoyoing the steering of your bicycle from
> side to side will propel it forward... slowly. Use a standing start.
Thanks, now I'm eager to see how it will feel.
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