# Motorcycles stop faster than cars

Discussion in 'The Perfect Line and Other Riding Myths' started by Tkacsman, Jan 4, 2018.

1. ### Tripped1Bitch called me a feminist.

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Half mass times velocity square. So a small difference in speed makes up for a large difference in weight. All else being equal, there are a pile of variables, reaction time (in the case of the motorcycle) rider skill, surface conditions.

Another fun one. If you ever plot that out, you lose the lesser half of your speed in the last two vehicle lengths, so as speed increases coming up a vehicle length short is more painful the faster you are going.
2. ### foxtrapperLong timer

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Nope, it would be initial velocity.

A vehicle going 100 mph, decelerating at 20 mph/s would take 5 seconds to stop. Mass never entered into the equation.

A second vehicle going 60 mph, declerating at 20 mph/s would take 3 seconds to stop. Initial velocity was different, and changed the time to stop.

A different rate of deceleration would also change the time to stop.

A vehicle going 100 mph, decelerating at 5 mph/s would take 20 seconds to stop.

Now of you want to talk about how hot the brakes get, we need to discuss mass.
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3. ### Tripped1Bitch called me a feminist.

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Bigger motors, better chassis, better suspension, better tires higher power to weight ratios
4. ### Tripped1Bitch called me a feminist.

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I was thinking more along the lines of kinetic energy......I'm also dog ass sick, so yeah, could be wrong.
5. ### foxtrapperLong timer

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The heavier vehicle does indeed have more KE than the lighter vehicle going at the same speed. And the heavier vehicle has to dissipate more energy than the lighter vehicle to stop at the same rate from the same speed.

But this does not come into play when holding a decelleration rate steady. As long as the brakes are up to the job of holding both vehicles to the same decelleration rate, both vehicles would stop at the same time and in the same distance, provided they started at the same speed.

Now, if one of the vehicles has undersized brakes and gets heat-soaked to failure, the rate of decelleration would change and the stopping time and distance would change.

Hope you feel better soon.
6. ### slartidbartfastLove those blue pipes

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Closer racing and greatly improved safety - so riders push closer to the edge, aided by tire technology. There are many more crashes than in the era of 500cc 2-strokes but far fewer fatalities.
7. ### slartidbartfastLove those blue pipes

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Winner!

A bigger vehicle has more mass to stop but has more traction for braking due to greater weight pressing down on the tires. Those familiar with the math and physics involved will realize that mass cancels out in the calculations.

The variables when calculating theoretical braking capability are center of gravity/stability (car wins every time) and traction. Traction is complex because, although bikes generally have better (stickier) tires, the shape of the contact patch is significant. A wide short contact patch from a square section tire (as found on a car) works better, which almost evens things up from a traction standpoint.
8. ### Pecha72Long timer

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U sure there are more crashes now? I mean, those 500cc two smokers were known as evil beasts.. Schwantz, Rainey, Doohan all ended their careers by getting injured, paralyzed in Rainey's case.
9. ### CaptCapsizeBeen here awhile

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Interesting thread and physic discussion. Not being a very experienced rider, I assumed a bike would stop quicker. I was wrong!
In retrospect it is similar to the mind set of some 4x4 drivers I have seen. They believe, since the can accelerate faster on slick snow packed roads, they can stop equally as well.
The other take away is braking practice improves stopping distance, and gives this rider better awareness of the distance required.
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10. ### Pecha72Long timer

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basically true.

But I would add in the context of this thread: More and more advanced traction control, launch control, wheelie control systems and gps based curve per curve adjusted engine mappings, as well as mappings to save the tyres until finish. Refined engine management is crucial there nowadays.
11. ### slartidbartfastLove those blue pipes

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Yes, I didn't want to take @st3ryder 's word for it so I checked. More crashes decade-over-decade but far fewer serious injuries and fatalities. Tracks and protective gear getting much safer allows racers to ride closer to the edge with less risk of serious injury. Result: More crashes.
12. ### markk53jack of all trades...

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So... how do you reconcile that with Colin Edwards and Reg Pridmore teaching riding?
13. ### markk53jack of all trades...

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Cycle World or Motorcyclist did their own test of it and found that wasn't totally true. A pair of CBR600RRs, one with ABS and one without, were used. The same expert rider did several runs after being familiar with the bike. In perfect conditions the expert could stop a few feet shorter, but in the rest where the road was rougher or wet they went longer than their own performance on an ABS machine. It was several feet difference. When only using rear brake the distances were crazy longer without ABS, but only a doofus would not use front brake... I guess there probably are a lot of doofuses (or is it doofi) out there.

Either way, practice is the trick if you don't have ABS and possibly even if you do.

One interesting thing - if the roadway is really slippery ABS could possibly add distance unless the rider takes control. I've experienced it with stopping in packed/icy snow. If I anchor it, the stopping takes a lot of distance, but if I work the brakes (yes, even with ABS) I can cut the distance down a bit. Seems working the brakes allows one to plow up a bit of snow with the tires impeding forward motion. But don't take my word for it, go learn yourself.
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14. ### JCoolLong timer

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They're either ''has been's'' or ''used to be's'' (by racing standards) , but most teachers are ''never were's''. Sorry if the shoe fits.
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15. ### slartidbartfastLove those blue pipes

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Living proof of the Dunning-Kruger Effect
16. ### JCoolLong timer

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The first step is admitting you have a problem , maybe there's hope for you yet.
17. ### st3ryderBeen here awhile

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Thank goodness for that.
18. ### st3ryderBeen here awhile

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All harnessed and made usable by rider electronic aides.
19. ### markk53jack of all trades...

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Of course they would be "has been" or "used to be" you forking idiot. If they were still racing (or doing whatever job) they wouldn't have time to teach. Duh!

As for the shoe fitting,it seems like I made a decent living at sales until I was injured and went back to school to get into engineering. From there I was also successful at that too, but as usual, when tough financial times came around the last one hired was the first one let go. I got back into teaching, which was great since Ohio has a decent retirement system. I've been headhunted, but teaching is far better for me. Good retirement when that time comes and a couple months off in the summer. Now THAT shoe fits! Make fun of teaching as much as you want. I'll be riding or lounging during the summer and in a few years be able to call it a day with a reasonable income, thank you.
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20. ### Anders-690R

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What's quicker on bikes than cars is the time it takes to go from non-braking to braking - simple biology, moving a few fingers takes less time than moving an entire leg/foot.
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