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TheBladeOfHades

Foot placement physics

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Ankle dynamics 

I wanted to post a better example of pedal dynamics on a euc to provide a helping hand for riders to understand how your foot placement directly affects your style and skill threshold. 
And I want to give everyone a baseline on the dynamics of balance over one axle.
We can train our muscles to perform many amazing things so everyone can place their feet wherever and compensate with our bodies, so styles and positions differ greatly and all work for the riders they belong to. 
Here is a concept that literally should put you on your heels. 
The flat of your foot is your axis that controls your wheel and should be equally distributed on the pedal, this creates a lower centre of gravity, allows for better stability at speed, better stability breaking, bumps and jumps become second nature, and overall ride enjoyment improves. 
The basis is simple, but a bit scary to get used to. 
Your foot has three contact points, your heel, ball of your foot and your toes. These rotate at your ankle to create a triangle that controls balance and movement. The premise of this style revolves around the main points between your heel and the ball of your foot, (hard point triangle) if just this part of your foot is centred on your pedal the axis of your wheel and foot are more inline with each other and greater control and stability is more natural. The hard points between ankle, heel, and the ball of your foot become more naturally inline with the axle of the wheel giving it a feeling of an extension of your leg. 
This allows you to use your heels as your gas pedal instead of leaning over onto your toes to accelerate or climb hills. 
Every speed wobble or break wobble is usually caused by being too far back on your pedals. 
At speed you are leaning out over the wheel and forcing the contact point of the tire ahead of true centre, this results in speed wobble with a pressurized wheel and the small contact point it provides, this is why lowering the pressure eliminates some wobble. The larger contact point allows for more movement of the centre mass  in the point of contact. Same in reverse for breaking, the heavy brake moves the centre of mass behind true centre and results in wobble. Once adopted the ability to move the wheel with agility under your body will instantly increase and with time will feel like an extension of your ankle and not something you ride on. Any veteran or naturally skilled rider can adopt or realize that is where their natural stability comes from, for new learners it cuts the learning curve dramatically. 
I will tag some videos to demonstrate the premise. 
 
Here Marty Backe rides an MSX up his famous "overheat hill" 
His rearward stance forces him to put all his weight forward to climb. You can see his heels bounce behind him as he puts his weight up on his toes to climb, this is how a rearward rider is forced to compensate for foot placement to achieve forward momentum. Either climbing or just cruising at speed. 
 
 
Here is a video of a young lady wearing ballet heels to ride, the small contact of her boots on the pedal shows the concept of the hard point triangle between wheel and rider. She needs to centralize her boots to ride but has no toes to lean up on. Her hard point triangle is set between her knees and the boot bottom depending on how tight they are. 
 
 
And lastly Fantomas, ripping around notice how he pushes the wheel to the fore and back to to create speed and achieve braking. He rides from his squat and rides hard on his heels instead of toes, he uses the hard point triangle of his feet to great effect. 
 
 
I hope this will help any struggling to advance understand the physics behind foot placement and the hard point triangle of your foot vs movement on a euc. 

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14 hours ago, TheBladeOfHades said:

This allows you to use your heels as your gas pedal instead of leaning over onto your toes to accelerate or climb hills. 

You need to expond on this.

 

14 hours ago, TheBladeOfHades said:

Every speed wobble or break wobble is usually caused by being too far back on your pedals. 

Not every speed wobble is caused by foot position.  Pavement irregularities can induce a wobble.    Based on my desert riding I suspect that high cross winds can induce a wobble.

I've never encountered a brake wobble.

Bruce 

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14 hours ago, TheBladeOfHades said:

I hope this will help any struggling to advance understand the physics behind foot placement and the hard point triangle of your foot vs movement on a euc. 

Unfortunately it didn't mean much to me at all. It doesn't help a lot when give a 15 min video of Marty riding rather than indicate a particular moment in the video that best illustrates what you're trying to say. I did enjoy watching the young lady in the red dress and watched that most of the way through. She didn't feature in the 3rd video so I skipped that one.

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New rider here, only have about 100 km behind me.

i went for a ride with @mrelwood last weekend and he immediately adviced me to “step forward” on my pedals. I had been riding with about a 2 cm overhand of my heel on the backside and he had me adjust my stance so that my heel was at the back edge of the pedal. This is on a ks16b. At first it felt uncomfortable, but accelerating became a lot more naturally and braking by “showing the wheel in front of you” felt about the same. I still need to adjust to this but it for sure felt more stable right away.

i have since developed a habit where my left foot is further forward than my right foot and i kinda stand a bit sideways on the euc. My left knee is also a bit further forward than my right knee. I have not grasped why i do this and i do not know how to correct it... i am too much of a newbie to reposition my feet whilst riding so i will have to figure this out at a later date... just dont want to create any bad habits while learning.

the original pads on the ks16 are too small for my 10.5 size feet, so i will cut some 5mm aluminum sheets to the size of my shoe and.mount them on top of the pedals. I have seen some mods done like this helre on the forum and most of them have the 1 inch overhang for the heel. You would thus recommend not to do this and have the heel at the back of the pedal? I guess the geometry of the foot has to be taken into account and measure the distance from the calcaenus to the base of you metatarsals, split these in half and put this center on the axis?

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Riding with one foot front and one back usually means you have your back heel off the pedal Just a tad to create balance left to right, your Heel has a faster reaction time to small bumps in the road. 
a natural movement using a strong foot and control foot style. 
my intention is to get people off their toes for back to front balance and gain a more stable stance with strong foot or both feet. 
thanks

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16 minutes ago, TheBladeOfHades said:

Riding with one foot front and one back usually means you have your back heel off the pedal Just a tad to create balance left to right, your Heel has a faster reaction time to small bumps in the road. 
a natural movement using a strong foot and control foot style. 
my intention is to get people off their toes for back to front balance and gain a more stable stance with strong foot or both feet. 
thanks

I got that.. but for me it feel like i am riding twisted left to right... ive read so e people use one foot fot acceleration and one for co trol and prefer this riding style... i am not sure that i like it though as it feels like i am riding sideways... 

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Perfectly normal, you lean into it with a shoulder. Gives you good weight transfer from left to right and front to back, and we feel like a superhero flying forward by extending into the open air. Personal style is just that, stability comes from muscle control and foot placement, as long as you can keep one heel pressed to the plate your agility will come naturally and personal style will flourish. 

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I'll give that a try on my trip along the Delaware Water Gap trail on Monday.

Thanks,

Bruce

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I had great trouble understanding @TheBladeOfHades’s explanation in the first post (as well as in the earlier topic), but the pencil drawing indeed made all the sense. Seems that I just think and tend to word the same thing differently. As @FinRider wrote, I pushed him forward a bit, like I have recommended many riders to do. A front to back centered shoe just isn’t a good place to be in, but it seems to be where many beginners find themselves. I have also seen a few beginner guides instructing to do exactly that.

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The key to this foot placement is making sure you have at least one heel on direct contact with a pedal at all times. Squatting or using a strong/control foot style are both valid for maximum control. For off-roading or carving/showing off I use a squatting style with my butt as my centre of gravity and move the wheel around under my mass. For top end gliding I switch to a strong/control style for better small adjustments at advanced speeds. 
always press a heel into the pedal, you might need to constantly remind yourself to do so (I know I did when I changed to this style)

 

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For safety reasons I suggest always using a squatting method of propulsion, we are are skilled and love to lean but you can achieve just as much by squatting down. Style factor is not to high (until you bust out some moves to avoid an intrusion into your ride) Going over bumps and holes you can do with your eyes closed (not ever suggested) because your over the axle evenly, back to front and right to left using your knees to do the lean at a lower centre of gravity. 

If you have ever seen a video of a bird that keeps its head still while the handler moves its body around you might understand my next implementation into your skill set. Try and squat the keep your upper half locked as you move the wheel under you, this will also keep a lower centre of gravity that supports your core instead of being dependent on it. 
happy to post any other quick iPhone videos of right/left pedal triangle or answer any other questions if there is any interest. 

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Today while out on my continuing quest to learn to ride in reverse I tried out your suggest foot position. My feet were much further forward than in my usual riding stance.  Heels just on the rear edge of the pedal and my toes overhanging the front edge.

I found that mounting brought my foot readily into the desired position on the pedal.  With my prior foot placement it could be anywhere from where I wanted it to be to too far forward.

I also tried it out on a steep hill.  Bending my knees instead of leaning my body forward provided better speed control.  No lifted heels, no extreme body lean which has on a couple of occasions caused me to come off the front of the wheel.

Thanks,

 Bruce

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Posted (edited)
5 hours ago, PennBruce said:

 

Today while out on my continuing quest to learn to ride in reverse

 

Sorry if this stance isn’t great for backward riding but happy you tried it forward 

thank you  

 

Edited by TheBladeOfHades

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6 hours ago, PennBruce said:

I also tried it out on a steep hill.  Bending my knees instead of leaning my body forward provided better speed control.  No lifted heels, no extreme body lean which has on a couple of occasions caused me to come off the front of the wheel.

I’m excited you have the feel for the weighted heel, check out another post I did called "the benefits of riding on your heels" 

explains a bit of the physics but mostly my personal experience while switching to the Sasquat style (lol) amazing for control and breaking, but not acceleration.

getting to speed can be accomplished by other means but riding at any speed is safer on your heels. 

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On 5/29/2020 at 4:25 PM, TheBladeOfHades said:

 

Excellent explanation. The physics makes perfect sense. I’m a beginner, learning on a KS-18XL, and all of the EUC tutorial videos that I watched instructed the rider to “center” the foot on the pedal. In doing so, I’ve noticed that this forces me to adopt a slight forward-lean to maintain speed; any attempt to ride in a more vertical posture induced braking (unless I compensated by lifting me heel).

I’m excited to experience how the foot position you describe will result in better alignment between my center of mass and the wheel axis. Thanks for taking the time to create and post this video. 

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