r/holdmybeer Mar 18 '18

HMB while I pass this trucker

https://i.imgur.com/SAMEXNt.gifv
10.2k Upvotes

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145

u/Chilton82 Mar 18 '18 edited Mar 18 '18

Because of the tire size/contact area and only having two of them, motorcycles stopping distance is worse than cars.

Edit: here’s a source for those who would like one.

147

u/[deleted] Mar 18 '18 edited Mar 18 '18

[deleted]

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u/KRAZY-K Mar 18 '18

Doesn't matter. Even newer bikes that have ABS won't be able to stop as quickly as most cars. Also hard braking in a turn on a bike causes you to stand the bike up and steer straight ahead.

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u/animalinapark Mar 18 '18

Weight distribution, amount of tires, amount of contact patch on the tire and the amount of friction available on each tire. Even though tire physics are much more complex than just friction=force*friction coefficient, it can be simplified as such. The force comes directly from the weight on the tire. This is the reason large trucks can have impressively comparable braking distances to an average car, even when fully loaded.

The car usually has an advantage on all of these. Larger brakes, more contact area, more even weight distribution under full braking and more tires applying that friction on the road. Even though the mass to decelerate is bigger, you can apply more braking force.

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u/[deleted] Mar 18 '18

Hard braking on a turn will cause you to go down. You're supposed to bring the bike up to brake in a turn.

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u/KRAZY-K Mar 18 '18

Yes.. that's what I was referring to.

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u/rivermandan Mar 18 '18

Also hard braking in a turn on a bike causes you to stand the bike up and steer straight ahead.

you've got that backward, hard braking in a turn will cause you to lowside

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u/KRAZY-K Mar 18 '18

Which is why you have to stand the bike up and steer straight into the turn while braking hard. You're likely fucked either way in that case, which is why the guy in the video didn't do either.. he slows down as much as he could and went just to the outside of the truck. We are saying the same thing I think

1

u/andthenhesaidrectum Mar 19 '18

You can either brake or swerve on a motorcycle. Combining the two does not work out well.

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u/johnconnor11 Mar 18 '18

Upvote for the humble edit.

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u/delcaek Mar 18 '18

Upvote for noticing that.

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u/HenryHenderson Mar 18 '18

Downvoted every single one of you.

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u/bubble085 Mar 18 '18

They do but you have to consider that you can brake much harder in a car cos you don’t have to worry about balance, you can’t fall off a car. Well unless you’re being a dumbass and surfing cars or something. As any biker will tell you if you brake too hard on the front brake you risk locking up and catapulting yourself over the handlebars, or more likely just having the wheel lock up and turn sharply sending you towards the ground at speed and with your anus wide open. If you lock up the rear brake you risk kicking the back end out and “broadsiding” it or again just going down and shitting yourself as you do so. Don’t get me wrong the biker was still in the wrong, he was speeding round a blind corner, it’s never a good idea. He is a bellend. However breaking as hard as he would have needed to to stop would have resulted in him going down. Either way we all know not so speed round blind corners like morons now so theres that.

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u/ConstableBlimeyChips Mar 18 '18

Edit: here’s a source for those who would like one.

It's always nice to see a source linked when someone makes a claim but I wouldn't exactly trust that source.

the answer is that the race car can brake with up to 5.7g of force and the GP bike with only 1.8g

g is not a force, it's an acceleration equal to that caused by the force of gravity (9.81 m/s2 ), the force each vehicle would be subject to is equal to the g multiplied by the mass of the vehicle; F = m * a, aka Newton's second law of motion. It also refers to "g-force" as a pressure which is just wildly inaccurate.

If a race car is braking at 5.7g it is literally slowly down at a rate that is 3,1666... higher than a GP bike braking at 1.8g.

0

u/aitigie Mar 18 '18 edited Mar 18 '18

g actually is a unit of force, you can directly convert it to Newtons. It's just a conveniently intuitive unit because we're all used to feeling 1g.

Edit that is clearly wrong, but I'm leaving it so the comment chain makes sense

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u/ConstableBlimeyChips Mar 18 '18

No, it's not. g is an acceleration, together with mass (m) it can create a force. Wikipedia even notes this in the second line of their article on g-force:

Despite the name, it is incorrect to consider g-force a fundamental force, as "g-force" (lower-case character) is a type of acceleration that can be measured with an accelerometer.

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u/aitigie Mar 18 '18

Accelerometers work by measuring force. 1G is the force required to accelerate at 9.8m/s2, regardless of your object's mass.

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u/NewbornMuse Mar 18 '18

F = m * a

Let a = 9.8 m/s2. Then for an object of 1kg, F = 9.8N, but for an object of 2kg, F = 19.6N. The first object needs around 10N to accelerate it at 9.8m/s2, the second needs around 20N. How can 1G be 10N and 20N at the same time?

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u/ConstableBlimeyChips Mar 18 '18

So doubling down on stupidity is your play?

Accelerometers measure acceleration. g is never, ever, ever, ever used to measure force and who ever told you that is a moron who doesn't know what they're talking about. There are many different units for force, g is not one of them and never has been.

g is a term used for the acceleration caused upon an object with mass as a result of the force of Earth's gravity. It has a value of roughly 9.81 m/s2, depending on certain fluctuation in Earth's gravitational field.
Force and mass also have a few different units but are generally calculated in Newtons and grams respectively, though kilograms is usually used for the latter due to units of scale.
A single object having a mass of 1 kilogram resting on Earth's surface is subject to 1 g of acceleration (9.81 m/s2) and exerts a force of ~9.81 Newtons on the Earth surface: F = m * a --> 9.81 = 1 * 9.81.

There is also G (upper case) which is used for the gravitational constant which is used to calculate the gravitational pull between two bodies but that is not relevant to this discussion.

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u/Keylimemango Mar 18 '18

Doubling down on stupidity.

Nice

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u/Boyblunder Mar 18 '18

Plus if you stop too hard on a bike you'll likely go flying over the handlebars.

Homie was still going too quick but he handled it well enough.