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This is why it is harder to get a larger wheel up a hill


RockyTop
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I know it's in my nature to take the opposite view, but after processing the proposed theory in the back of my mind I'm not quite certain that the contact patch location has to do with larger wheels being more difficult to move up a hill.  Keep in mind I'm no physicsologist, but I often pretend to be one on the forums.  :whistling:

I think it possibly has to do more with the length of the pedal arm (pedal to axle) distance and size of the pedal.  I'm postulating that if you shorten and make the pedal support length the same on a larger wheel as a smaller wheel the torque force you can apply should be the same.  Or increase the pedal size enough to allow more force to be applied.

If one could mount the Mten3 pedal support on a Monster wheel one should be able to apply a similar force resulting in a greater motor power drive to balance it out if the control boards were located in the same locations and shell / battery weights made the same.  I wonder though if the firmware needs to be tweaked for different pedal lengths though.

I might be wrong, but that's my theory.  Maybe imagine an infinite flat gimbal riding surface.  In a horizontal postion both wheels move the same, but as the surface is tilted up the contact patch moves to the front of the tire's original spot.  The riders still lean at the same angle.  Gravity still acts in the same direction.  As the surface tilts up more the larger, heavier wheel needs more effort due to overcoming gravity,  but due to the longer pedal cannot apply much torque to the shell.

With the Pulse Glider the pedals were mounted very high making it quite nimble.  It would be interesting to see how a Monster with short pedals support arms rides like.

Edited by Hunka Hunka Burning Love
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17 hours ago, RockyTop said:

At first it did not make any sense as to why it is harder to get a larger wheel up a hill then it hit me!!

It is astonishing how simple an apparently hard to grasp problem can be made when it is as well and briefly explained as this ?. Great explanation  @RockyTop.

It is also amusing having just come from the pages of waffle that instinctively tell you a concept is just wrong in this thread ?

 

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15 hours ago, RockyTop said:

I plan on getting a set of these angled side pad wedges from EUCGUY  to help with the hills. 

 

are these going to be sold to us they look really good

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3 hours ago, Hunka Hunka Burning Love said:

 

I think it possibly has to do more with the length of the pedal arm (pedal to axle) distance and size of the pedal.  I'm postulating that if you shorten and make the pedal support length the same on a larger wheel as a smaller wheel the torque force you can apply should be the same.  Or increase the pedal size enough to allow more force to be applied.

I agree that the length of the pedal arm has some effect.  A shorter arm Would give you a more direct leverage.  A larger percentage of your weight would be directed into tipping the wheel.  I came up with a few mechanical solutions to this but the unicycle Gods of simplicity would likely not approve.  

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5 hours ago, esaj said:

Sounds about right, but also if you use a "stiff" ride-mode, the wheel tries to stay horizontal against the gravity, and you're also "fighting" the motor. I found out that with the stronger motors of KS16B & S (800W & 1200W respectively), I'm having much harder time getting the wheel to accelerate on steep hills than the 16" Firewheel with 550W motor. What I ended up doing was to switch the KS's to medium ride-mode, and accelerating uphills is no more an issue. Likely the small "give" on the pedals makes it easier to get higher proportional "error" in the control loop and thus command the wheel to accelerate... For heavier weight riders it's probably not as much of an issue, but the wheels weight over quarter of my body weight  :P

When you put some wheels on soft mode it allows the wheel to stay tilted forward a small amount.  This kinda cheats the geometry allowing more in front of tire contact line. 

After looking at the physics I kinda felt bad for the light guys with small feet. At least they still get better distances and less overheating. 

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Stone Tower - a more forward pedal stance for the right foot

I had good luck today (no blown MOSFETs, no uphill walk offs, topped a previously not topped Hill) by both gripping the Monster and by advancing my right foot (left normal for stability) to increase leverage on the pedal when weighting it on the uphill climb.

The sensation of a highly torqued wheel in slow movement forward took some getting used to but it climbed the hill (Stone Tower - Lynn Woods - South approach) as I had hoped☺.

Stone tower - Lynn Woods

 

 

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9 minutes ago, Bob Eisenman said:

 by both gripping the Monster and by advancing my right foot (left normal for stability) to increase leverage on the pedal when weighting it on the uphill climb.

I have heard several others adopting a staggered foot pastern.  I like it when I can remember to use it. 

That is one beautiful fire watch tower!  Your videos make me miss my home towns of Rochester NH, Andover NH and Arlington Mass.   I also miss Hampton Beach!  I don't miss the white stuff.

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2 hours ago, RockyTop said:

don't miss the white stuff.

I used to do some tech work for 'Kim' (S. Korean) (over) a decade ago before he moved to the Atlanta GA area ( 130 miles SE of Chattanooga ). He said it was 'hot' but he was getting used to it. His daughter (& I in 1975) graduated from UMass Amherst.

http://www.scholarena.com/eb/129/Hyung-Goo-Kim-SAJ-Genetics/

 

I went to the Grand Olde Opry a long time ago in Nashville. I remember eating at the 'Black and White' cafe.

Nice video!

 

Edited by Bob Eisenman
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