Stopping Distance NEEDED from 1/2 mile?

[Tufbusa]

The subject of braking doesn't come up on this site very often. The subject of chrome and speed is extremely popular, not so much on that often ignored little thing called "Braking Skill". I'd say those threads such as this one (https://www.hayabusa.org/forum/gene...7671-who-knows-stopping-distance-150-mph.html) didn't interest you much at the time until stopping the beast suddenly becomes a concern.

At 160 mph you are covering about 235 feet per second. If it takes one second past the finish line to get the brakes applied you have just over a thousand feet to stop. Since braking apparently isn't on your advanced riding skills list, you have choices to make. Shall I use the front brake only or should I use both brakes? If I choose to use the front brake as hard as traction will allow, just how much rear brake can I apply without high-siding my arse into the heavens? How much grip do I have in my choice of tires, enough to maintain traction under severe braking? Will the front tire reach optimum traction temperature when the brake is applied? Questions are many, answers are few! We are not blessed with braking skills from the womb, they must be earned through training and practice.

Good luck on your goal.

 

[bazooki]

I just read that entire thread about braking from 150. Very entertaining and interesting. The supplied chart link has a required stopping distance of 1/4 mile from 165 mph. I realize this is a general chart and not specific to a type of bike or braking capabilities of bike or rider or conditions but it certainly is a good starting point and information I can use. I have 6 rounds of 156 mph stops under my belt now and I know how much runway was left for me and what effort I was putting in to slowing the bike. Now we will have to use trial and experience to find the limits of a busa with new higher speed capabilities.

 

[Karl_1052]

Thanks Outlaw. You have introduced a bunch more variables that I hadn't even thought about yet. Yes, my brain is going to explode. LOL. With the 1/2 mile I am more concerned about my launch, plus I need to win the 1/4 mile portion of the event, so I think I am more likely to keep pressures lower than higher. I am also working on my position on the bike, trying to lower wind resistance as much as possible.

Hi Karl!

eace:

Another variable is how smooth is the braking area?
I have on been up in a plane there, so I never got to the end of the runway.
If it is a rough or dusty surface, that will cause issues with distance.

 

[TZ750d]

A good answer can be easily calculated with a little simple arithmetic.

1) Assume you will travel at least an additional 1/2 second
before you can get on the brakes hard.

1/2 second is pretty quick, since you would not want to "hammer "
the front brake, and skid the front tire........

a) at 200 MPH, 1/2 second about
equals 1.466 x 200 x 0.5,
so about = 150 feet.

2) From 200 mph, a MotoGP rider, on typical runway pavement,
could probably achieve a reliable deceleration rate of f = 1.2.

A skilled rider, would maybe develop f = 1.0 decel,

and a typical street rider would achieve f = 0.8 decel.

3) One can use a standard formula to calculate stopping distance from a known speed.

a) Distance (d) about equals the speed (S) squared,
divided by the deceleration factor times the constant 30.

b) d = S squared / 30f.

4) Examples:

a) stopping distance from 200 mph if you are as good as a MotoGP star.
a1) d = 200 squared divided by 1.2 PLUS the "reaction" distance of about 150 feet.
a2) 200 squared = 40,000
a3) 40,000 / 1.2(30) = 1,100 feet of decel.
a4) add the reaction distance of 150 feet
a5) stopping distance for the MotoGP rider is 1,250 feet.

b) For the "skilled" rider the total stopping distance
about equals 1,350 + 150 = 1,500 feet

c) for the average rider, the total distance = 1,650 + 150 = 1,800 feet.

5) Assume you have 1/4 mile of paved shutdown, which today = 1,320 feet.

a) The MotoGP man stops with 70 feet ( 3 - 4 car lengths) to spare. Are you that good ?

b) The "skilled guy" needs 1,500 feet, but has only 1,320 feet.

b1) 1,500 - 1,320 = 180 feet.
b2) "Skilled guy" goes off the end of the track at about 75 mph (reverse calculation)

c) "Average guy" needs 1800 feet, and goes into the dirt at almost 110 mph
c1) Think about riding your 'Busa' at 100 in soft dirt, with trash and stumps....

 

[outlawbusa]

Scott, you should answer some of Tuff's questions!

 

[TZ750d]

Scott, you should answer some of Tuff's questions!

I read some of the "other " thread, and looked at the "chart."

The chart is conservative, and looks right at least for 60 mph.

Not sure I understood what our friend was actually asking,
and when he posted the picture of the bike with the rear wheel
2 feet in the air, I was wondering how the rear brake played an important part.

Can somebody help me understand all this,
since I have come late to the discussion ?

Scott

 

[TZ750d]

I went back and looked more at "the chart,"
and it works for me. One just has to understand
just how much "G force" they can develop for a best stop.

That, of course, involved finger sensitivity,
steering ability, "threshold braking" skill,
brake pad and disc(s) condition,
tire type and condition; all that stuff.

 

[scotty - 12]

oops. Please disregard