EUC dangerous for super tall riders??

[wstuart]

So I'm just starting off in this hobby and I have a question about wheel cutoffs.  

I am 6'8" and 225 lbs.  I am concerned that my height in combination with my weight might put an extra load on the wheel.  

Correct me if I'm wrong but when we lean to accelerate the wheel (and the wheels accelerates  to counter the lean)  we apply a torque, or angular force to the wheel.  If my 225 lb center of mass if further from the wheel would it apply more torque to the wheel?  Here is my rough bar-napkin calculation:

Torque = distance × force.   (Foot x lbs)

If my center of mass is 10% higher (than a 6ft tall person) then my effective weight is 10% more.  My 225 lbs might be equivalent to 250lbs for a 6ft tall rider.  Does this seem right??

 

I'm learning on a V8f and I'm trying to be very cautious with my lean.  Should I be looking for only 2500w plus wheels?  HT only?  I also have an MSP HT that doesn't seem to stress at all with my weight.  Should I not try to push the MSP HT past 25 mph? Could I get away with a v11 or a kinsong 18L?

Do any of you know really tall riders 6'6" or taller?  Do they have trouble with wheels cutting out?  

Edited February 2, 2022 by wstuart

[.....]

I think its weight more than height. Altho being taller, COULD improve your leverage when using pads. At your size you need to step into the bigger wheels. Its not the speed or range, its the headroom. Obviously a smaller wheel can manage you as you are still new. It's almost a given, that you will start to demand more and more from a wheel and not even realize it. You could probably ride an 18L, but you'd have to be mindful of how you pull hills or accellerate. Even at my puny 130lbs, I was sagging my 18L dagerously low, very easily. I consider myself a slightly aggressive rider, but I have the benefit of being a toothpick. You would fare much worse than I, under same agression. The easy answer is... of course its dangerous for ALL of us. If you ride VERY conservatively ALL the time, you have less to fear. However, it only takes a moment of asking too much, for you to realize your folley.

Here's some food for thought. At 6'3 130lbs, I can sag my SHERMAN battery down to dangerously low overhead, within 10 minutes of a full battery. I can make it do this on flat ground if I merely ride 40mph for a few moments and lean into it to get up to 45mph. Granted, this is pretty fast and the battery bounces back quickly to near full. I just mention this, to give you some context of how power demands can be surprising, and its not a linear thing. I have videos of how I ride, and its really not as hard as one would think.

If you plan to travel and ride at 30mph for distances, go big or go home....

Run a 3rd party app and monitor your voltage on the HT. I would suspect you can cruise around 30mph+ on it(Gw HT), as long as its not extended uphill or long into the battery's range. Its pretty tough to overpower the motors, as they can handle a LOT more than stated, for peak current. Overlean cutoff is a problem, but I find battery sag (for my ride style) to be more a concern. There are no definitive numbers for safety, its a moving goal post thing. The trick is, to watch the reality of how you use it and ride accordingly, or re-evaluate your wheel choice.

Edited February 2, 2022 by ShanesPlanet

[The Fat Unicyclist]

I am a taller and heavier rider... Though not quite as tall (or light) as you...

My initial comment is, don't buy an Mten3, or any other smaller wheel. 

But a larger diameter wheel 18"+ should be fine for your dimension!

One further comment... I previously thought it applied to heavier riders, but it may actually be not significant for taller riders... Don't lean with your whole body. 

Keep your shoulders back and your back straight and push forward with your hips! This will keep you more comfortably upright, but also shift your CoG forward (and back) as required. 

I can make more comments too (from the perspective of this size rider)... Just ask specific questions.    

[yoos]

6 hours ago, wstuart said:

Torque = distance × force.   (Foot x lbs)

If my center of mass is 10% higher (than a 6ft tall person) then my effective weight is 10% more.  My 225 lbs might be equivalent to 250lbs for a 6ft tall rider.  Does this seem right??

the distance in this equation is the distance from the axis to the point where the force is applied. Unless you are using powerpads (or handlebars which are present in some obscure archaic EUCs or some other leverage to tilt the EUC) the furthest you can apply your weight is the edge of the pedals. So height is irrelevant here while weight is important. If you are using powerpads be careful indeed not to overpower the EUC. 

6 hours ago, wstuart said:

Should I not try to push the MSP HT past 25 mph?

It should handle your weight fine. Still, I would advise to not go fast while learning. Ramp up speed slowly (e.g. stay below 15 mph for 100 miles, then below 20 for another 100, then 25 for 500 miles etc. your mileage may vary depending on your type of riding). There are EUC-specific hazards (like wobbles appearing at high speeds to inexperienced riders -- many threads about that on the forum) that can cause a crash even if you have previous scooter/motorcycle etc experience.

Another tall-rider problem is increased wind drag which might slightly reduce your max speed. Look out for alarm beeps in any case. And watch out for low-hanging fruits branches, road signs etc.

[Eucner]

13 minutes ago, yoos said:

the distance in this equation is the distance from the axis to the point where the force is applied. Unless you are using powerpads (or handlebars which are present in some obscure archaic EUCs or some other leverage to tilt the EUC) the furthest you can apply your weight is the edge of the pedals.

Actually, distance in the equation is the horizontal distance from the axis to the center of gravity. If not using pads and riders center of gravity is not above pedals, you would fall off the wheel.

[yoos]

2 minutes ago, Eucner said:

Actually, distance in the equation is the horizontal distance from the axis to the center of gravity.

It's a bit more complicated than that. First of all, the "x" in "distance × force" implies a vector product so indeed if the force is vertical then only the horizontal distance enters.

But more importantly, the body is a complicated mechanical system and not a rigid body. For example, you can move your c.o.g. beyond your toes and still prevent a fall (this is done instinctively, but you can also analyze the mechanics and understand why this works). You can also apply a higher force than mg by jumping, i.e. using your leg muscles to amplify the force. That is a known way to test the EUC overpower limit: strongly press with you toes (as if to jump) at the front of the pedals. In this maneuver your c.o.g remains roughly above the axis but for a short duration you apply a high force at the pedal edge and produce a high torque. Since you use muscle strength for this instead of moving you c.o.g this is safe, because the overpower (if it happens) will result in a short duration pedal dip instead of faceplant. 

Unlike the rider, the EUC shell can be considered rigid and that is why it is correct to say that the max leverage distance on a padless EUC is indeed the pedal length. If we consider a stationary regime (riding at constant speed with body posture fixed) then the max torque would indeed be pedal length (or half-length to be precise) times mg. A dynamical situation is more complicated and in general taller riders should have an easier time exerting extra force on the pedals using body movements.

[mhpr262]

I am 6'3'' and I weighed 290lbs without clothes and gear at my worst and my V10F has handled my weight just fine. As long as you dont accelerate abruptly or attempt to go over a big bump when the wheel is already at its limits it will always warn you in time.

[Richardo]

At 6'1" and 200lbs I want to say the mten3 still works for me, but on the other hand I have wiped out on it without warning beeps so it'd be dumb to push it to other (big) people. Incredibly fun wheel though, and I don't think I'd ever give it up.

Edited February 2, 2022 by Richardo

[wstuart]

10 hours ago, yoos said:

It's a bit more complicated than that. First of all, the "x" in "distance × force" implies a vector product so indeed if the force is vertical then only the horizontal distance enters.

But more importantly, the body is a complicated mechanical system and not a rigid body. For example, you can move your c.o.g. beyond your toes and still prevent a fall (this is done instinctively, but you can also analyze the mechanics and understand why this works). You can also apply a higher force than mg by jumping, i.e. using your leg muscles to amplify the force. That is a known way to test the EUC overpower limit: strongly press with you toes (as if to jump) at the front of the pedals. In this maneuver your c.o.g remains roughly above the axis but for a short duration you apply a high force at the pedal edge and produce a high torque. Since you use muscle strength for this instead of moving you c.o.g this is safe, because the overpower (if it happens) will result in a short duration pedal dip instead of faceplant. 

Unlike the rider, the EUC shell can be considered rigid and that is why it is correct to say that the max leverage distance on a padless EUC is indeed the pedal length. If we consider a stationary regime (riding at constant speed with body posture fixed) then the max torque would indeed be pedal length (or half-length to be precise) times mg. A dynamical situation is more complicated and in general taller riders should have an easier time exerting extra force on the pedals using body movements.

Ah this helps.  I just realized something.  The EUC has no idea how tall I'm or how high up the leaning force is coming from.  The EUC only experiences the force applied to the pedals.  

This helps - thankyou

[meepmeepmayer]

Beware of another tall person pitfall: you might bump your head on some bridge, tree branch, or likewise structure that looks tall enough to go under but isn't with the extra pedal height (and maybe the extra helmet height). A helmet helps here.

Edited February 3, 2022 by meepmeepmayer

[wstuart]

Good point!!!! Thankyou.  I already have trouble with this even without a unicycle. 

[.....]

6 hours ago, meepmeepmayer said:

Beware of another tall person pitfall: you might bump your head on some bridge, tree branch, or likewise structure that looks tall enough to go under but isn't with the extra pedal height (and maybe the extra helmet height). A helmet helps here.

I clean ceiling fans with my head by accident, frequently.

Edited February 3, 2022 by ShanesPlanet

[gon2fast]

I actually think height+mass works better with EUCs as one does not have to lean into the wheel as aggressively to get performance. On the other hand, I have almost fallen over the front of my wheels on steep inclines. Knowing your center of balance as a tall rider is very important in certain situations.

Edited February 3, 2022 by gon2fast

[.....]

26 minutes ago, gon2fast said:

I actually think height+mass works better with EUCs as one does not have to lean into the wheel as aggressively to get performance. On the other hand, I have almost fallen over the front of my wheels on steep inclines. Knowing your center of balance as a tall rider is very important in certain situations.

Tall people can bend down to get shorter. Short people.... neener neener, can't do much about it!

[Felix]

10 hours ago, wstuart said:

If we consider a stationary regime (riding at constant speed with body posture fixed) then the max torque would indeed be pedal length (or half-length to be precise) times mg. A dynamical situation is more complicated and in general taller riders should have an easier time exerting extra force on the pedals using body movements.

I think body height matters more than pedal length assuming foot and pedal are always in contact and pedal-to-leg angle is the similar and rigid. A tall person just has higher center of gravity therefore body is acting as a longer lever, more torque is exerted on the axle.  I'm with OP's original assumption (even though it seems he changed his mind:) .

[yoos]

1 hour ago, Felix said:

A tall person just has higher center of gravity therefore body is acting as a longer lever, more torque is exerted on the axle.

Torque is r x F - that's a vector product: |r x F| = xF_z-zF_x (assuming flat motion, i.e. no turns and side motions. x is the horizontal direction of movement, z is vertical). If you are just using your weight then F_z=mg and F_x=0. Thus, only x enters the torque while z (which is the height of your c.o.g.) does not.

[techyiam]

At the outset, since motor torque is along the same direction as the axis of rotation, no other components of torque would be relevant pertaining to acceleration or braking.

yoo's argument on the MAXIMUM torque that a rider can exert on the euc hinges on the assumption that the rider is not rigidly "coupled" to the pedals. If power-pads are used, or if the rider is wearing ski boots that are latched on to to the pedals, then it would be a totally different story (coupled).

Having said that though, in the case where both a short 300 pound rider and a very tall 300 pound rider move their hips forward to accelerate, both have to be equally careful in how much he moves his hip (center of mass) forward to accelerate, whereas, if both leans forward to accelerate, the taller rider has be extra careful in how much he leans forward.

I am making an assumption here that both riders can exert equally a maximum torque that can easily over power the wheel.

Edited February 3, 2022 by techyiam

[Felix]

I'm only saying that i think in this sketch the long lever would produce more torque on the axel than the short one. The rest is too complex for me

[techyiam]

If the rider stands rigidly on the pedals wearing ski boots that are rigidly latched on the pedals, then the sketch would be a more accurate analogy.

[.....]

Human body is a lever, but it also has a few hinge spots. I DID used to get called 'stick boy' a lot.

Edited February 3, 2022 by ShanesPlanet

[mhpr262]

Yeah, being taller doesnt mean more leverage unless your boots are firmly attached to the pedals or you use power pads. Without those a taller person can just lean a little less forward than a short person before he falls over.

[Felix]

7 minutes ago, mhpr262 said:

Yeah, being taller doesnt mean more leverage unless your boots are firmly attached to the pedals or you use power pads. Without those a taller person can just lean a little less forward than a short person before he falls over.

On one hand you say being taller doesn't mean more leverage (which it does imo) , on the other you say a tall person can't lean as much forward as a short one. So do you do agree with me that for the exact same lean a tall person makes the EUC work harder? Even without power pads or attached to the pedals etc.

[yoos]

13 minutes ago, Felix said:

exact same lean

if you mean "same angle lean", then yes, the taller person exerts more torque. If you mean "same shift of c.o.g in the horizontal direction" then the torque is the same. In either case, like stated by @mhpr262, @techyiam, unless you have powerpads or other ways to lock yourself in with the wheel (as opposed to standing on the pedals), the max torque anyone can exert [while moving horizontally with the EUC, i.e. no jumping or other intrabody dynamics] is governed by your weight and pedal length. It's just that the taller person achieves this max torque easier in the sense that his body leans to a lesser angle to place his c.o.g. above the front pedal edge.

[mhpr262]

The center of gravity of a person's body cant be further forward than the front edge of the pedal or else he will fall off the EUC. A taller person with a higher up center of gravity will be able to lean forward less than a short person until their center of gravity exceeds that limit. Like in this diagram: 

 

Blue line is the short person, green line is the tall person, red line is the front edge of the pedal.

[Felix]

6 minutes ago, yoos said:

if you mean "same angle lean", then yes, the taller person exerts more torque. If you mean "same shift of c.o.g in the horizontal direction" then the torque is the same. In either case, like stated by @mhpr262, @techyiam, unless you have powerpads or other ways to lock yourself in with the wheel (as opposed to standing on the pedals), the max torque anyone can exert [while moving horizontally with the EUC, i.e. no jumping or other intrabody dynamics] is governed by your weight and pedal length. It's just that the taller person achieves this max torque easier in the sense that his body leans to a lesser angle to place his c.o.g. above the front pedal edge.

I believe OP was talking about same angle lean (same horizontal shift obviously has same effect) , and the work the EUC has to do for it compared to a short guy/girl: For him the EUC has to work harder which IMO is the point of this whole thread