Twike • Hacker News Board

Re: Twike

#141

Post by chrismorgan » Wed, Jul 21, 2021, 2:13 PM UTC

SigmundA wrote: post #128

chrismorgan wrote: post #105

This sort of electrical/pedalling hybrid is an interesting space, but one where legislation is often a real downer. I’m currently planning to build a velomobile that I can live out of while cycling round Australia for a year. A trailer too, designed around a digital piano and some sort of fridge (either a production model or one constructed manually from a compressor). It’ll end up heavy enough¹ that I’ll want to put…

In all my research mechanical -> electrical -> mechanical double conversion is significantly less efficient than a direct mechanical drivetrain. It seems to come down to about 80% for the best electrical vs >95% for mechanical [1][2]. Also there is a weight issue the generator is at least as heavy as the motor and thats a big problem on bikes. Trains do it because they need precise traction control and have little co…

Your 80% figure seems rather spurious, coming I think from extrapolating a gross simplification of some 2009 figures for much bigger motors. My vague understanding is that smaller motors are hard to get as efficient. Some things I was looking at last year suggested things keep improving and that in excess of 90% was in theory quite attainable now for such motor sizes, though in practice you probably won’t find it on the market. But I did find components that should combine to something like 85–87%. (I don’t think I wrote my findings down, or if I did it was on a device I don’t have access to at present. But a quick search shows https://outriderusa.com/pages/electric-bike-efficiency claiming a motor efficiency of 93%, which if paired with a generator of similar efficiency would yield 86.5%, assuming no transmission loss which is of course unreasonable, and assuming the efficiency stays the same at lower power levels, which is likely screamingly wrong.)

>95% for chain systems assumes good components excellently-maintained. In practice chain drives are generally somewhat less efficient, commonly more like 85–90% is what I think I read, with poorly-maintained ones often more like 65–75%. This is where an electrical drivetrain could really shine: it’ll require roughly no maintenance while maintaining its not-best-in-class-but-still-pretty-good efficiency.

These figures are all rather nebulous, and get muddied a lot further once you’re putting a battery into the mix too, trying to take the power from your feet and augment it with another 200W of power from a battery (but preferably without feeding your foot-power through the battery). Then I go from being an amateur that knows just enough to be dangerous to a rank ignoramus.

For my purposes, an electric drivetrain would probably be markedly less efficient, but if it can be enough more convenient, it could be worthwhile anyway. I also have a pet scheme in mind where you simulate 100% efficiency by adding a little more power from the battery to compensate for known losses. I feel that could fit within the intent of legislation, if only that legislation allowed electric drivetrains in the first place.

Re: Twike

#142

Post by drewcoo » Wed, Jul 21, 2021, 2:21 PM UTC

everdrive wrote: post #126

gumby wrote: post #116

Earlier quoted context omitted.

> Pretty sure the car is the most harmful invention of the 20th century. A bit of perspective: the automobile cleaned up cities, which used to have a huge infrastructure to manage animal waste. The automobile enabled freedoms: not just freedom to travel, which the manufacturers emphasize, but freedom of association, unlocked a wider freedom to work, in particular for women, and in general, ironically, enabled the gro…

Are you two equivocating between different kinds of "clean?" Animal waste vs. exhaust, metal, and brake and tire particles?

Is it equivocation to call both a puddle and a downpour wet? No.

Same for clean here. These are not different definitions of the same word. They are different members of the same category.

Re: Twike

#143

Post by kiliantics » Wed, Jul 21, 2021, 2:27 PM UTC

everdrive wrote: post #131

el_nahual wrote: post #12

Another example of how, if you had to design a vehicle for passenger city/suburban use, you would never ever ever come up with an ICE sedan, or to be honest even an electrical vehicle of "normal" proportions. Pretty sure the car is the most harmful invention of the 20th century. The damage it has done to the environment, our health, and social fabric is hard to grok. A couple edits for clarification: - I'm talking ab…

I think this is a great point, and I've always been on board with the general damage done by cars. The solutions I read about are nearly always focused around the cities. Now, this makes sense, since most people live in cities, and so you can make the biggest impact there. But what about people who live in the country or rural areas? What solutions are there for those sorts of folks?

Trains can still go into the countryside. They used to in much of the US and still do in a lot of Europe. Then there are buses too.

Re: Twike

#144

Post by kiliantics » Wed, Jul 21, 2021, 2:29 PM UTC

engineer_22 wrote: post #118

LightG wrote: post #70

Earlier quoted context omitted.

100% this. I live near a school and witnessing the quality of social interactions from Mums* , encapsulated by their SUV-tanks as if controlling a Gundam, is a sight to behold. * Sorry, it mainly is Mums in this situation. And I'm fully cognizant of ejut Dads/Men driving madly in other situations.

I have heard in german-speaking countries they call those style of automobiles "hausfraupanzers". For me, it evokes a silly image of a militant soccer-mom in a tank. I love it.

In the UK, they get referred to as Chelsea tractor, or Chelsea tank. (Chelsea being a rich part of London where they first got popular)

Re: Twike

#145

Post by benrbray » Wed, Jul 21, 2021, 2:30 PM UTC

everdrive wrote: post #131

el_nahual wrote: post #12

Another example of how, if you had to design a vehicle for passenger city/suburban use, you would never ever ever come up with an ICE sedan, or to be honest even an electrical vehicle of "normal" proportions. Pretty sure the car is the most harmful invention of the 20th century. The damage it has done to the environment, our health, and social fabric is hard to grok. A couple edits for clarification: - I'm talking ab…

I think this is a great point, and I've always been on board with the general damage done by cars. The solutions I read about are nearly always focused around the cities. Now, this makes sense, since most people live in cities, and so you can make the biggest impact there. But what about people who live in the country or rural areas? What solutions are there for those sorts of folks?

I've always fancied the German style of having dense clusters of houses/shops around a major train station / highway, with farmland in between. Look at satellite imagery [1] around Stuttgart, for instance. You can totally have walkable city centers in less crowded areas.

Of course Germany is not the United States. I don't know anything about agriculture, or to what extent the needs of German agriculture vs US agriculture would be met by such an arrangement. But this being HN, maybe someone knowledgeable can chime in!

[1] https://www.google.com/maps/place/Stuttgart,+Germany/@48.662...

Re: Twike

#146

Post by htek » Wed, Jul 21, 2021, 2:31 PM UTC

Helmut10001 wrote: post #56

el_nahual wrote: post #12

Another example of how, if you had to design a vehicle for passenger city/suburban use, you would never ever ever come up with an ICE sedan, or to be honest even an electrical vehicle of "normal" proportions. Pretty sure the car is the most harmful invention of the 20th century. The damage it has done to the environment, our health, and social fabric is hard to grok. A couple edits for clarification: - I'm talking ab…

Add to this list: The estrangement that happens when people drive with their SUVs. A car built like a tank entails a certain behavioral or interaction with other people that is detrimental to social cohesion and empathy.

I love the freedom of bicycling, but I hate dealing with people driving cars. I sort of understand why the more militant bicyclists call them "cagers." As I remember angrily explaining to a motorist who thought nothing of fishtailing into my lane after barely passing me (I was biking in the shoulder between the white line and edge of the asphalt), "if I make a mistake, I get killed, if you make a mistake, I get killed."

Re: Twike

#147

Post by isbadawi » Wed, Jul 21, 2021, 2:40 PM UTC

Xylakant wrote: post #138

usrusr wrote: post #77

Earlier quoted context omitted.

One problem is that there's a long tail of car use cases that are served terribly by things like car-sharing. For example if you rent a car for a few hours of driving, two weeks of parking at some trailhead or remote resort and then driving back it's inevitably priced for the wear and tear that would happen if you spent the entire two weeks doing nothing but sleeping and driving. Rentals that aren't dead-set on the p…

I think people underestimate the price of owning a car vs. renting one. I can rent a VW Golf in Berlin for 500 EUR per month. (assuming you buy it new, own it for 5 years and drive 15000km/year) https://www.adac.de/_mmm/pdf/autokostenuebersicht_47085.pdf That means I can rent that car for ~5 month and still come out ahead.

There must be a typo somewhere in your comment, I don't understand how 350/week for 5 months is better than 500/month.

Re: Twike

#148

Post by lucideer » Wed, Jul 21, 2021, 2:41 PM UTC

benrbray wrote: post #49

el_nahual wrote: post #12

Another example of how, if you had to design a vehicle for passenger city/suburban use, you would never ever ever come up with an ICE sedan, or to be honest even an electrical vehicle of "normal" proportions. Pretty sure the car is the most harmful invention of the 20th century. The damage it has done to the environment, our health, and social fabric is hard to grok. A couple edits for clarification: - I'm talking ab…

For anyone who has trouble understanding this perspective because they've lived in car-dependent hell their entire lives, I recommend the Not Just Bikes channel. He does extremely detailed comparisons of US cities vs Netherlands and other places. Here is a recent one [1]. For me, I always felt that something was wrong about American cities / suburbs but I couldn't quite put my finger on it. Then, I spent a few months…

Another +1 on Not Just Bikes.

Something many people overlook about Netherlands is how reliant on public transport they aren't. City design enabling local amenities to actually be truly local (within walking distance) is an underestimated boon. That's enormously easier to do in practice without the burden of highways and carparks.

There's also a general myth about Europe being "forced" into smaller more localized city plans by having older cities with smaller streets (accidentally creating more "local" urban environments) but that's not really the case. Road-widening projects have been common in many old European cities for centuries; the cities that are human-friendly are the ones who've undertaken the gargantuan task of reversing a lot of these car-oriented urban plans[0]

[0] https://www.theguardian.com/cities/2015/may/05/amsterdam-bic...

Re: Twike

#149

Post by kiliantics » Wed, Jul 21, 2021, 2:44 PM UTC

YeGoblynQueenne wrote: post #92

el_nahual wrote: post #12

Another example of how, if you had to design a vehicle for passenger city/suburban use, you would never ever ever come up with an ICE sedan, or to be honest even an electrical vehicle of "normal" proportions. Pretty sure the car is the most harmful invention of the 20th century. The damage it has done to the environment, our health, and social fabric is hard to grok. A couple edits for clarification: - I'm talking ab…

>> As a species we are more than capable (as evidenced by the OP!) of building a variety of modes of transport that are better in most every way (utility, externalities, price) to cars. As a species, yes, but -and I know this sounds hokey- we are not in control of the automobile industry. Market forces are -and we don't control those, either. Like so many mythical creators, we have lost control of our creation and it…

This is a completely ahistorical take. The roads didn't all come out of nowhere and the railways that used to go everywhere didn't just magically disappear. And market forces didn't make these transformations either. Regulation is what got us into this mess and regulation can get us out.

We have also regulated away many things that were favoured by markets but had negative consequences. And there are plenty examples of people who are happy to do the less convenient thing and even end up enjoying it. Including switching from cars to bikes, which has happened in a number of European countries.

Re: Twike

#150

Post by qwertygnu » Wed, Jul 21, 2021, 2:47 PM UTC

gumby wrote: post #123

sudosysgen wrote: post #119

Earlier quoted context omitted.

The automobile did not clean up the streets. The personal automobile was much too expensive for that. Buses and trams and metros and transport trucks and railways and bicycles cleaned up the streets. The average person didn't own a car and use it daily until much after the streets "cleaned up".

Do you have some references for this bold statement? The development of busses, trams, metros etc increased urban traffic (much as widening highways increases traffic, and traffic jams) including animal-drawn traffic, at least in the cities where I have read up on the history of urban transportation (in particular London, Paris, and New York). The GP mentioned Mumbai, which only recently banned animal traffic. It was…

Do you have any references for yours?