Bike Rumor: just wow.

Questions about bike hire abroad and everything light bike related. No off-topic chat please

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youngs_modulus
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Location: Portland, OR USA

by youngs_modulus

I've seen more than my share of bad technical journalism about bicycles and bike-related subjects, but this is the worst by a country mile:
https://bikerumor.com/2019/11/25/teslas ... destrians/

The BR author argues that because a concept car's body panels are advertised as "hardened" that such a vehicle would be a clear and present danger to cyclists the moment it hits the road.

The author has no idea how crash safety regulations work, let alone physics. But that doesn't keep him from presenting bald speculation as fact:

"Safety is an afterthought"

"Cyclists [...] will likely be facing essentially a brick wall (moreso than any other car)."

Neither of those things is true--not even a little bit. The author has no idea what he's talking about. Worse, he has no idea that he has no idea what he's talking about.

I'm posting this to warn other WW folks to read BR's technical content with a jaundiced eye. They often get technical details wrong and uncritically accept marketing claims as fact. Yeah, that annoys me, but articles like this are downright deceptive, even if they're not intended to be.

BR has never been a stalwart of rigorous journalism—the site has been credibly accused of overt plagiarism by respected journalists like James Huang, among many others.

Between accusations of plagiarism and this pseudo-technical sensationalist dreck, I think people should know that BR drives many journalists and engineers to spork their eyes out.

(For what it's worth, I'm a mechanical engineer who specializes in simulation. I've done plenty of impact analyses—"explicit dynamics" is the term of art—and the BR article is way, way off base. It's not right. It's not even wrong).

cdncyclist
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by cdncyclist

While I didn't make much of the article, I am curious to know your insight as to why their suppositions are wrong, and what are the relevant factors regarding safety if a collision should occur. I assume that is just other factors / variables that are more relevant rather than the properties of the material?

by Weenie


youngs_modulus
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by youngs_modulus

Yeah, you're mostly on track about my objections. The biggest one, though, is that the writer apparently saw "hardened steel" and decided that was Real Bad. Also, he apparently decided that none of his concerns had ever occurred to anyone at Tesla.

Asking "is this safe for cyclists" is a totally valid question. But that question has been answered; the BR author was just too lazy to look it up.
Michael Gushulak wrote:Most, if not all, trucks to date have been built around a heavy-duty chassis with more forgiving body panels. With Cybertruck, the strength is built in the body panels themselves by using Ultra-Hard 30x Cold-Rolled stainless steel.
First of all, the guy is clearly unfamiliar with the distinction betweeen unibody and body-on-frame construction. Gushulak didn't make a peep when the Honda Ridgeline debuted in 2006; that was (AFAIK) one of the first unibody trucks. BTW, nearly every single car on the road today is built with a unibody. So the "forgiving body panels" bit is a fantasy. Cars have been built in the manner proposed for Tesla's truck for literally my entire life—and I'm pushing 50!

Hardness is a weird concept, so I don't fault Gushulak for misunderstanding it. It has to do with stiffness, yield strength and a few other factors. But frankly, 300-series stainless isn't very hard as steels go. It can be work-hardened and even nitrided to make it harder; none of that matters to a cyclist who's been mowed down by a vehicle. As BR commenters pointed out, the driving factor in a bike/truck collision is the relative masses. I've been hit by a car. Body panel compliance is tertiary.

If Gushulak wants to complain that Tesla is a hype-driven company, I won't argue. But the guy is out of his depth here. Pedestrian impact standards have been on the radar of European regulators for 15 years. Even a cursory Google search would have made that clear, but Gushulak could't be bothered (evidently).

You want high-strength steel in crumple zones, including the body panels cyclists contact as you run them over. The higher the strength, the more energy the steel
absorbs (in plastic deformation, AKA permanent bending). I don't mind that Gushulak got this wrong. My objection is that he clearly thinks he's the first ever to consider the question. He's not.

Tesla is subject to the same pedestrian impact standards that apply to Volvo—they both sell cars to the European market, after all. Has Volvo exceeded those standards? Great! Wanna hold Tesla to the high standard Volvo has set? Great! Then publish an op-ed that says so, rather than "I have a hunch that truck is too pointy! Or too blunt!"

I'm all for cars that are safer for cyclists. But this article was lazy and incurious—and it should be ignored.
Michael Gushulak wrote:[...] hopefully, we can all agree that the design they’ve presented us needs to take a second look at the safety of those who will be sharing the roads with it.
Easy there, tiger. It's Michael who needs to take a second look—or a third. The guy needs to do his homework—you know, like Tesla's engineers already have.

(I'm no Telsa fanboy. Compliance with with Euro pedestrian-impact standards was surely a requirement from the beginning).

Impact simulations happen long before tooling is cut for body panels. I wouldn't ordinarily fault Gushulak for not knowing that, but he's clearly happy to hold forth without concern for whether he's making any sense. He's not, and that's why I felt I should speak up. Fundamentally, this is concern trolling disguised as bike-tech journalism. Let's call it what it is.

cdncyclist
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by cdncyclist

Thanks for the info and insights, interesting reading!

youngs_modulus
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by youngs_modulus

Hey—no problem. I'm glad that helped.

Here are a few other tidbits about the relevant physics:

Hardness is not the same as stiffness. All steels are essentially equally stiff, no matter their hardness. So hardened stainless is no stiffer than annealed (non-hardened) steel. Sheet thickness is the driving factor in (for example) how stiff a hood/bonnet is when a cyclist lands on it.

And that cyclist wants a relatively stiff hood that will absorb lots of energy before contacting the engine. A "soft" hood will provide minimal deceleration until the hood hits the engine block, at which point there's no cushioning at all. A stiffer hood means lower peak acceleration (g) and thus lower risk of injury.

The European pedestrian safety standards include detailed requirements about bumper height, deceleration and mitigating head impacts.

My problem isn't that the BR author didn't comprehend the underlying science. I don't mind that he has no idea that regulators require car companies to design for pedestrian (and, to an extent cyclist) impacts.

My objection is that the guy did zero research and presented his opinion—one entirely untainted by factual support—as something on which "we can all agree." This is Dunning-Kruger in action.

Finally—and this is secondary to the other stuff—the BR author sketchily implies that he was physically present at the Tesla unveiling with phrases like "we were treated to a live demo" and "after the show." It's bad journalism to imply that you were on the scene when you weren't. I can't say whether the author's implication was intentional—it could be shady or it could just be sloppy. Either way, it's not good.

Butcher
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by Butcher

The Tesla is a prototype. As far as I know, prototypes do not have to meet any standard. That truck was a sales ad to generate interest and money.

I read the article and the statement about safety. I agree with you, nothing mentioned was based on facts. The article is not news, it's just an editorial at best.

Unibody SUV's have been around way before the Ridgeline. My 81 VW Rabbit pickup [I know, it just looks like a pickup] is unibody.

youngs_modulus
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by youngs_modulus

You're totally right about unibody trucks. The Ridgeline was far from the first--Jeep's Cherokee went unibody in 1984. And sure--your Rabbit counts in my book.

I don't mind technical editorials at all—James Huang's "JRA" series on Cyclingtips is great. But this article was so ill-informed that I hesitate to call it an editorial. It's a little like an editorial warning of the threat fairies pose to mountain bikers. No matter how much fairies terrify the author, the threat is still imaginary.

TLN
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by TLN

Butcher wrote:
Tue Nov 26, 2019 4:57 pm
The Tesla is a prototype. As far as I know, prototypes do not have to meet any standard. That truck was a sales ad to generate interest and money.

I read the article and the statement about safety. I agree with you, nothing mentioned was based on facts. The article is not news, it's just an editorial at best.

Unibody SUV's have been around way before the Ridgeline. My 81 VW Rabbit pickup [I know, it just looks like a pickup] is unibody.
Heres's pictue of Ridgeline unibody.
Image
All that is hidden under varouos panels in the fronts: headlights, hood, frony bumer and side panels, that designed to take impact. Same applies to body on frame: rigid frame, carries less rigid body parts and then panels on top.

Currently tesla cybertruck is designed inside-out: most rigid parts are on the outside of the truck and not meant to deform on impact. And that was proven on video. Having no panels to absorb damage sounds a bit more dangerous to me. However (again, my thought) that it only applies to slow-speed impacts. At 60kmh it will be equally bad.

youngs_modulus
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by youngs_modulus

TLN wrote:
Tue Nov 26, 2019 11:59 pm
Currently tesla cybertruck is designed inside-out: most rigid parts are on the outside of the truck and not meant to deform on impact.
Interesting! Got a source for that?

I'm skeptical, but let's see what you've got.

TheRich
Posts: 505
Joined: Tue Jan 01, 2019 1:36 am

by TheRich

When up against a soft pink body, does it matter?

It's a weird article though, if you want to bag on Musk, there's plenty of obvious material.

TobinHatesYou
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by TobinHatesYou

TheRich wrote:
Wed Nov 27, 2019 5:38 am
When up against a soft pink body, does it matter?

In practical terms? Yes, there's a reason why modern cars look the way they do, with high bumpers, grilles, hood panels designed in certain ways. If I were to broadside you at 15mph with my 1980 300SD, you can bet the damage to your body would be considerably worse than if I had hit you with any modern car.

But let's use something even more relevant. Say you're one of those guys riding around with a counterfeit non-certified helmet and you take a pure gravity fall from 1-2 meters. It is possible to experience >800G peak on your skull...which would almost certainly be fatal. Add just a few centimeters of crushable EPS and that reduces the G forces to <300...which still leaves the possibility of TBI, but is survivable.

We're constantly pushing the envelopes for safety standards. I'll happily buy safety equipment that can back up its claims of being, say, as safe or safer than the competition in more extreme circumstances. In this case extreme circumstances would be something like 17mph instead of 15mph. It doesn't sound like much, but it is.

TLN
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by TLN

youngs_modulus wrote:
Wed Nov 27, 2019 4:03 am
TLN wrote:
Tue Nov 26, 2019 11:59 pm
Currently tesla cybertruck is designed inside-out: most rigid parts are on the outside of the truck and not meant to deform on impact.
Interesting! Got a source for that?
I'm skeptical, but let's see what you've got.
Oh, no source.
But they're hitting doot panel and there're no damage. I assume same applies to hood and other panels, that won't deform on impact.
All the modern cars, unibody or body on frame covered with frames (bumper, hood, side panels) that will absorb some impact.

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Konsi
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by Konsi

I seriously doubt Tesla is looking for the truck to be on the European market. With the available specs, you most likely would need a license for proper trucks, not just for cars, with all the other consequences (max 80km/h on highways, 60km/h on all other roads ...). And I hope to never see this on the roads here either, not only the impact safety seems doubtful, but the driver would have a hard time seeing cyclists in the first place.

TLN
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by TLN

I think it's all clever marketing. They're entering new segment, which is very brand loyal. They want to be on the news. A lot. That's the goal right now. In 2 years they will redesign truck and make it compliant with all the standarts.

by Weenie


ND4SPD
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by ND4SPD

Butcher wrote:
Tue Nov 26, 2019 4:57 pm
The Tesla is a prototype. As far as I know, prototypes do not have to meet any standard. That truck was a sales ad to generate interest and money.
+1

Tesla Cybertruck is just a concept/prototype, ergo, this whole discussion is pointless.

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