Polaris OBark

Ice skating works because ice melts under pressure, whereas the phase diagram for most other solids show that pressure has the opposite effect.

That's junior high level physical chemistry. I don't think you are in a great position to comment on the "level of technical knowledge on this forum," but would point out that no one is holding an AK-47 to your head and flipping the safety on and off to convince you to stay.

TC1

The previous commenter literally self-applied the same term.

Polaris OBark

We make some exceptions given an extreme level of arrogance infused with idiocy.

TC1

That is more clearly described in the second reference, which was added subsequently. If you thought you had a "Gotcha!", here, reconsider. With regard to other solids, who cares? Those are not relevant to the topic at hand.

And leave y'all to your delusions about hydroplaning? Perish the thought. Actually it had already occurred to me that educating the unwilling is not, in fact, my responsibility.

That said, despite your claim that this is junior-high material, if you read the previous citation, you will find that important discoveries on this topic have been made as recently as 2019. I cannot speak for you, but I wasn't in junior-high that recently.

ThermionicScott 

Weird that we have to explain that an expression of humility isn't an invitation to be insulted...

TC1

That does seem to describe this environment, to my surprise and disappointment.

smd4

I’m sorry. I thought based on what I wrote that you would understand that I run those tires.

smd4

Says the guy worried about breaking his frame from bashing on it with a 5 pound sledgehammer…

Polaris OBark

Then you will fit in well.

Iride01 

Who the heck is riding a fat tire bicycle at 29.3 mph?

zandoval 

Nearly lost it just the other day in soft, light gravel just about 2cm deep. WOW... What was that? Was I just Hydroplaning on gravel?

No... Its called "Ravelplaning"

https://www.roadbotics.com/2019/10/0...call-raveling/

Still... I don't know its math, but It was quite an uncomfortable experience to be sure...

TC1

So you don't find "I don't need no stinkin NASA arithmetic to tell me hydroplaning on a bicycle is moot. Ain't happening." to be a stupid remark? Maybe it was in jest, but that was exactly my point -- they needed to dial it down in order to generate a response.


I note with interest how fast and furious ad hominem attacks appear here, and yet, how few comments discuss the fact that NASA's investigation finds bicycle hydroplaning to be completely possible. I wonder why...

Polaris OBark

People who make NASA Youtube videos. Please try to keep up.

TC1

Says the guy running 23s at 140psi.

Come on. Grow up. And that goes for most of you commenting lately. If you are all emotionally hurt that you cannot refute NASA's investigation described above, I'm sorry for you. But 'tis better to remain quiet and be thought a fool, than to speak and remove all doubt.

If y'all want to turn this thread into a non-stop ad hominem attack, go right ahead. I won't acknowledge any more of that behavior, and it just illustrates that my proof above is beyond question. On the other hand, if you want to discuss bicycle mechanics, give that a try.

Polaris OBark

Because people don't find your argument by appeal to authority either compelling or accurate.

smd4

He used the term in a humble and self-deprecating manner; you wielded it as an insult. Big difference.

Polaris OBark

It isn't a "mathematical proof." That is pure ignorance on your part. It is merely a testable hypothesis, formulated in terms of a simplistic, ad hoc equation.

It can easily be tested, and either corroborated or refuted.

All of the evidence that I am aware of leads to the latter.

You berate everyone for their failure to mis-understand what that 1963 paper presents in that way that you have. The comical aspect of this, as well as your bizarre tirades and ranting and raving is that you seem equally and inexorably convinced it makes you look somewhat intelligent, whereas it actually starkly reveals you to be a complete and total buffoon.

Russ Roth

Lets use your formula, a 25c tire, common to a race bike, at 100psi which is a common race pressure would mean that a bicycle would have to be moving 100mph in order to hydroplane, please show me the pro rider on a pro tour bike that achieves that speed in the dry, they don't because at a certain point its no longer possible for the bike to safely stay upright. It is possible, as your video shows, when the bike has been designed with fairings and more and I doubt you'll find one of those nut balls with the solid brass pair willing to try in the rain. Further, the formula you bring up is a generic one that doesn't take into account things like tire shape and tread pattern, its why tires like goodyear's aquatread and other brands' equivalents can change that equation and perform at higher speeds than a standard tire, by being able to direct the excess water through channels and away from the center section of the tire it increases the speed at any given pressure that a tire will hydroplane. Likewise, the narrow shape of a bicycle tire isn't accounted for in that equation because of its ability to cut through the water, bicycle tires don't need a specially designed tread to move water away, they're narrow enough to do it naturally. As to what speed the hypothetical nut job would need to be at to hydroplane their 25c tire at 100psi is an unknown because while anything is hypothetically possible, the reality is that it really isn't.
Even using a motorcycle tire as a comparison doesn't work, motorcycle tires are inches wider than a fat bike tire, and as a result the fat bike would need to hit higher speeds at equivalent pressure to hydroplane. Dropping the pressure to 36psi in a 25c tire to get it down to a reasonable 60mph also isn't a solution, while it would mean the tire can do it at 60mph using the formula and not the real world scenario of actual tire shape, getting a bike and rider up to 60mph on a tire that will pinch flat at 10mph just isn't going to work. So yes, you've proved everyone wrong, hypothetically you could, in some ridiculous long shot manage to hydroplane a bike. In the real world, its just a stupid argument to even try to stand behind. But have fun with it.

shelbyfv

I try to avoid riding in the rain, but.... Figure 38mm slicks at 40 psi, 210# rider and bike. At what speed would hydroplaning occur, if it did. Thanks.

Trakhak

Perhaps our new contributor can weigh in on the assertion that heavier bikes guarantee a better workout than lighter bikes.

cyccommute 

The actual paper does not say what you think it says. There is no mention of “hydroplaning”. They describe a complex water/ice matrix that is slicker than water alone.

First off, a typical motorcycle like the one used in the video is about 32” wide which is the width of the handlebars. This link shows an overhead picture of the motorcycle



The pegs are only slightly narrower than the grips on the handle bar and the grips are typically 5.75” or 11.5” total. The hydroplane is about the width of the pegs as see in the video or roughly 20” which is close enough to 2 feet to be “about”.

Second, in the run up to the water and in the water itself, there is no visible “flopping” of the hydroplane. The hydroplane in this picture looks extremely rigid with bracing added to keep it rigid.





Third, the motorcycle dives into the water when the front wheel drops too deep and turns the hydrofoil in wing which pulls the motorcycle into the water. The wheel is getting much more assist from the hydroplaning of the hydrofoil than the wheel is hydroplaning.

Fourth, if you put hydrofoil on a motorcycle and hurl it across a body of water, of course it is going to “hydroplane” but it hydroplanes on the hydrofoil and not on the tires. Here’s the full quote from the Solid Works article says

Without the hydrofoil, the motorcycle couldn’t do the skimming for long enough because it is not stable.

The NASA constant is 10.35 for the conversion to miles per hour (instead of knots). The “new” constant in your undated link is 10.2, which doesn’t make that much of a difference. For example, using your 30 psi, the difference in speed goes from 57 mph with the “old” constant to 56 mph. That some difference, isn’t it?

No, they aren’t “hydroplaning”. They are losing traction and nearly every one of the crash is initiated by a lateral movement of the bicycle caused by the action of pedaling the bicycle.


No, “friend”, the question is if the video that you showed of people crashing during a time trial in the rain illustrated hydroplaning. Given the pressure of the tires used…as stated by someone from a professional racing team…it is not possible for the time trialer to have crashed due to hydroplaning…as per the NASA and NHSTA studies. They crashed because of lack of traction but that is not​​​​​​​ hydroplaning.

Possible, maybe. Probable, no. And you kind of moved the goal posts. You provided “video evidence” of what you called hydroplaning during wet bicycle time trials. When people pointed out…correctly…that the bicycles in your linked videos weren’t hydroplaning, you moved from “yes they are” to “it’s possible”

I was being sarcastic…mostly. He shows quite clearly that it would be extremely difficult to hydroplane on a bicycle. The values show that quite clearly. It is difficult to get a bike up to 60 mph and that’s the low end.

Jeremy Roy hit 81 mph in the Tour de France in 2016 but the article I linked to says that racers in that event run about 115 psi. Hydroplaning at that pressure occurs at 110mph. He’s 30 miles shy of the speed needed for hydroplaning at that pressure. It’s possible but not probable.

You are the one isn’t understanding.

L134 

"...further substantiated the fact that hydroplaning can create a very serious slipperiness problem to most pneumatic-tired vehicles."

Copied and pasted out of the NASA study. If one were to read the study, one would see references to "partial hydroplaning."

Having had one hydroplaning experience on a bicycle in some 60 years of cycling I don't really care whether or not it was complete hydroplaning or partial, it was most unnerving. Although the NASA study is most definitely way over my head, I do not believe that anywhere in that study is it proved that it is impossible to hydroplane on a bicycle and my personal experience is enough to convince me that even if the paper does say it is impossible (and it doesn't), then the paper is wrong. I was descending a mountain pass in the rain on a self supported tour on a tandem. The descent was straight, the stoker was still and the bike was behaving in ways I have never experienced before or since (thankfully). I have no idea how fast we were going but we were probably on 1.25" Schwinn Le Tours maybe pumped to 85 psi if someone wants to calculate anything. Total weight had to be over 300 pounds. Tell me I am wrong, tell me TC1 is wrong, I don't care. I don't believe that regardless. Be thankful it may be rarer than rare. Be thankful to not have experienced it but be hesitant to categorically dismiss it because someone told you NASA said so. I don't think they did.

CrimsonEclipse

Let's see:

PSI-Hydroplane speed
5psi/23mph
10psi/33mph
15psi/40mph
20psi/46mph
30psi/57mph
40psi/65mph
50psi/73mph
60psi/80mph
90psi/98mph
120psi/113mph

CAN you hydroplane?
yes

Will YOU be hydroplaning?
HA! no.

shelbyfv

Thanks, I'm relieved.

cyccommute 

No one has refuted NASA’s investigation or even tried. In fact, we accept those results. It has been pointed out to you many times that the speeds needed to hydroplane an essentially unattainable for mere mortals. We have also pointed out what you call “hydroplaning” in wet time trials isn’t hydroplaning. A record set for a 16 km time trial is 51.6 kph. For the metrically challenged, that’s a 10 mile time trial at 32mph. He hit a max speed of 75 kph (45mph). Since the bike he is riding probably isn’t running 20 psi in the tires, the chances of it hydroplaning are slim and none.

Tell you what: go get a set of 23mm tires. Pump them up to 1.4 psi. At that pressure, according to the NASA formula, the bike should hydroplane at 12 mph. Now find a nice lake and go skim across it. Make sure that you film it because hilarity is going to ensue.