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Wheel weight


Tech Nossomy
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When discussing the wheel and its merits with others I sometimes interject 'free transport'. No one ever picks up on that, perhaps because it is thought of as not achievable, even if it is desirable. When there is more time and the discussion goes into more detail I also often mention that it is a very light mode of transport, meaning to bring the point forward that weight is actually a criterion. When I mention it and continue to emphasise it, I often get a look that is something between puzzlement and irritation. I think it is because it is thought of as neither achievable nor desirable.
I am not convinced that Priuses and Teslas are the future shape of cars, they're just too heavy. Their weight has consequences for their required power output and the conditions that are placed on our infrastructure. So despite being propelled by renewable energy, they are still insanely wasteful and where there is waste, there is a business opportunity.
 

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Increasing speed and range can be done if the rider can deal with it, so it's a soft (rider dependent) constraint.

Decreasing (mostly battery) weight and (mostly battery) cost is a hard (because technical) constraint and you can't get around it by clenching your teeth together and doing what needs to be done (if you know what I mean);)


That being said, if my ACM was 10 kg instead of 20 kg, it would behave totally differently (less stable and less glued to the ground). So weight isn't only bad (cost is, of course).

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The weight is a problem when you lost control of euc. Euc comes safer for people surrounding if they are lighter. 

When you try to change the direction of a mass it come harder as this mass is bigger. Acceleration, braking and turn come slower and you need more time to complete those. Also if any unexpected force act (like a bump) you need more effort to recover the control.

Lightness is also performance. All kind of speed competition looks for a optimal power/weight balance. Where the weight are the price for power, not a setup for performance (unless for lightness)

Sorry for those "weight is safe" devotes but the euc isn't a car, is more like a bike where nobody wants a extra gram 

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The cost to build the transportation infrastructure for cars is the same regardless if you're using Teslas or Hummers, and parking especially doesn't decrease as you go more electric. The parking lot, the strip mall, and endless miles of roadway are the defining features of American living, and those are here to stay as we eventually go 100% electric.

And lest we forgot, cars are supremely comfortable and safe compared to most other form factors.

I'm with @Demargon on this one; smaller lighter wheels at the same power and range are better in every way including safety for others when (not if) you crash. If you want more stability simply go with a bigger diameter wheel.

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Yeah, for my EUC, I kind of prefer the heavier , larger wheel over my smaller lighter wheel. It adds a lower center of gravity stability...to counteract my significantly upper center of gravity :( .

As for the car discussion, I agree that weight is an issue. But I think they are totally different issues. A car weight can have a much more significant impact on performance, gas mileage, style, etc. For example, my current car is a Honda CRZ. It is based on the old Honda CRX, but due to additional safety regulations, the car comes in heavier, so it is limited to being a 2 seater. IF you could modify or somehow de-regulate the safety requirements, construction, etc...maybe have it manufactured as an "experimental vehicle", some very interesting things might have happened...giving it back seat, much greater gas milage, more cargo room. I dunno. That's a lot of "IF's". 

 

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What about aerodynamics?

In transport vehicles, they are removing the weight because they are replacing weight with downforce. Commercial trucks are still being heavy.  what I do believe though that vehicle to person's weight ratio should be considered more. A car of 400/500kg (how much a car weighs? when I was young I remember I saw figures of tons on old cars) is normally carrying 2 persons... assuming they are like me that's 170kg, the rest is energy "wasted" for the motor to carry itself and what it is holding it. In EUC 2 pieces of EUCs that are around, 20kg are carrying the same 170kg. That makes it hugely more efficient to my opinion as long as it meets the range we travel.

Mentioning above, aerodynamics also affect the efficiency of the vehicles. In EUC travelling, aerodynamics is efficiency is bad as we need to balance. think about when you are riding against the wind. Cars, on the other hand, cut through the winds, so their final efficiency in pushing it is less reduced by air resistance as opposed to the EUCs.

As a matter of safety, modern cars also see lighter (to a limit) as safer as @Circuitmage and @Demargon mentioned, because the car is more capable of absorbing impacts. As for me, my EUCs range from 7.5kg to 13.5kg. It's perfectly fine to ride my 7.5kg every day, but when I know I need to handle heavy objects the 13.5 handles much better could also be because the bigger one is 16" too

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I would say aerodynamics, at our speeds is of minor concern, unless we are racing. Then we could get into wearing all the fancy equipment and trim down our EUC's for weight (or whatever) like the bicycle racers do. Then, though, the race riders will be 4' tall (like horse riders) and I won't have to worry about competing!

It is a bad thing that we are pushing a human, flat facing the wind. On the other hand, if you have a tail wind, I imagine that would greatly increase our range...having a human sail and all.

 

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Weight is a much more important form factor for bicycles or EUCs than it is for cars. As long as most people prefer to drive cars with ~100kW instead of ~20kW, weight will remain a rather insignificant design factor for cars. As long as the motor has 100kW anyways, there is no pressing reason to throw out the stereo or the air conditioning or... to reduce weight thereby also reducing comfort.

Only if we are short of power (bicycle) or want to carry the device (EUC, bicycle), weight becomes a significant form factor in transport.

Having said that, for me weight is a primary factor in choosing an EUC. As of yet, 19kg is still a deal breaker for me.

Edited by Mono
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On 29/09/2017 at 5:35 PM, LanghamP said:

And lest we forgot, cars are supremely comfortable and safe compared to most other form factors.

Your lifetime chance to be killed by a car is about 1%.

Apart from the motorbike, I am not aware of a less safe form factor than cars. Taking the train, walking or cycling in the absence of cars, or taking the airplane have all a much smaller death toll than cars.

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7 minutes ago, Mono said:

Your lifetime chance to be killed by a car is about 1%.

Apart from the motorbike, I am not aware of a less safe form factor than cars. Taking the train, walking or cycling in the absence of cars, or taking the airplane have all a much smaller death toll than cars.

Walking is neither safer nor more comfortable that cars, either by passenger mile nor by per trip.

Trains and planes aren't comfortable, especially planes, and both trains and buses leave you vulnerable to physical assault by people who don't look or act like you.

Both pedestrians and cyclist using roads that cars are sharing have exceptionally high rates of collisions with the resulting injuries and deaths. I suppose one could stay in dedicated trails in parks. Speaking for only the US, it's almost entirely car centric at the cost of other forms. And all those other form factors require, without exception, walking to get to the form of transportation which leaves you vulnerable to a car collision.

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7 hours ago, LanghamP said:

Walking is neither safer nor more comfortable that cars, either by passenger mile nor by per trip.

But it would be kind-of funny to make this to be an argument for cars as transportation device, as the essentially only reason why walking is not safe is cars. How safe walking is varies very much by country though. The US isn't like the greatest of all role models in this respect, IIRC in some European countries it's ten times safer to walk than it is in the US.

7 hours ago, LanghamP said:

Trains and planes aren't comfortable, especially planes, and both trains and buses leave you vulnerable to physical assault by people who don't look or act like you.

You forgot to mention the common sniper shooting people driving by...

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