Be The Bunny! Safe riding and motorcycle survival thread

two completely out of context bits of info from the internet; I have way more resources at home:

"Rider magazine once reported the results of stopping a Yamaha from 60 MPH AVERAGED 87 feet in a series of nine attempts."

Of course, it doesn't say WHAT Yamaha but since it was Rider, we can at least assume a street bike.

From the State of Virginia's "stopping distance chart" (for use as a Court reference) stating "The courts shall furthertake notice that the above table has been constructed, using scientific reasoning, to provide factfinders with an average baseline for motor vehicle stopping distances (1) for a vehicle in good condition and (2) on a level,dry stretch of highway, free from loose material."

"Automobile brakes" stopping distance from 60 mph=171 feet.

Like I said, two completely out of context bits of information. I'll look up the various magazine's tested stopping distances for the Seca 550 and others in its class when I get home; meanwhile why not try to find the stopping distance for say, a Ford Taurus or a Dodge Ram pickup.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

Hmmm...not sure what kind of measuring device the folks from Rider were using, but a CycleWorld test of the Honda CBR600RR in May 2009 yielded a best 60 mph stopping distance of 140 feet.

That's with a professional rider, and a heap better brakes and wider tires than our old Yammies.

Also interesting was the best 60 mph stopping distance using the back brake only - 304 feet! Now you know why it's such a problem that many riders only stomp the back brake in a panic stop, and why the MSF instructors want to burn it into your brain to get in the habit of using both!

Herb

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

The page on this link has a chart with stopping distances (average? typical?) for motorcycles from different speeds.

Just a little more info for the discussion...

Herb

http://www.motorcyclesafetyinfo.com/mot ... aking.html

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

The figure given (134 feet at 60 mph) is about in the middle of this table:

http://www.batesville.k12.in.us/physics/PhyNet/Mechanics/Kinematics/BrakingDistData.html

Of course the 134 feet is some average figure when both brakes are applied correctly. Using only the rear brake, the braking distance could easily be over 300 feet for instance. Using only the front brake is not as bad, but will take longer too.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

Hi Everyone --

Just wanted to say THANKS to all who have taken the time to post here.

I am (more or less) your audience and this thread pushed me to pull the trigger on a sixsixone suit, some sweet kneeguards, helmet halos (extras for gifts to buddies) and a stupid-bright rainsuit.

I thought I was Properly Scared before I read this thread but noooooo.....

 

I knew Rider's number was optimistic; here we go:

From Cycle World's 550 comparison test, 8/82 issue:

From 60 mph: Yamaha Seca 550- 128' Kawasaki GPz550- 134' Suzuki GS550M- 128' Yamaha 550 Vision- 133'

Those distances are realistic.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

don't discredit the back brake either. i was test riding my wife's virago after a tire change and i didn't adjust the rear brake right after putting the wheels back on. i was amazed at how much harder it is to stop with no rear brake.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

It's up to 85% braking power in front and the rest with the rear. A more common figure given is 60-40. Yes you *need* what the rear brakes give and you need to know how to modulate both to maximize the breaking power according to the speed you have reached and other factors (like a wheel locking).

Emergency breaking is probably the trickiest thing to do for common riders. That's why I try to do it as little as possible. :twisted:

 

Everywhere I go it is natural for me to use both brakes together. I always use both at the same time, that way I wear them out evenly.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

jd,

Same here. I always use both brakes. That way if I ever need to stop RIGHT NOW hopefully it'll be an ingrained habit and I'll grab/stomp both.

Herb

 

That is a good habit to have, I mean look at it like this-why just use the front when you run the risk of breaking to hard and dumping the bike(especially on dirt), I had to learn that the hard way on my dirtbike, and why just use the back when it takes to long to stop. Just use both and you are good all the way around. I have never taken a motorcycle safety course, riding anything on wheels has just come naturally, and using both breaks together makes the most sense of all.....

 

well I'm quite new to riding bikes ( my first one isn't even running yet) but I encountered a potentially ugly situation from the "other side" of the story. It fits even more with the recent discussion of braking distance, so I thought I'd share.

Two days ago I was driving a 2 ton grain truck with a water tank loaded with 1800 gallons of water down a county road. Due to construction on a nearby highway, the road now served as a detour, increasing the traffic about 6 times. As I was driving, i noticed a bike approaching me from behind. The bike came up and passed me (both riders were wearing full gear from what I saw). However, once they passed me, they had to make a quick right turn to follow the detour, so they almost immediately began to brake. Even with brakes and downshifting, I had to pull completely into the oncoming lane to avoid them. I don't even want to imagine what could have happened if there was oncoming traffic that day, or anything else.

Regardless of which can stop quicker, a bike or a car, a weighted-down truck take significantly more stopping distance. being cautious includes being in front of a vehicle, not just behind.

I'm sorry if what I just said is the wrong direction for the thread or has no bearing at all. I simply wanted to show another side of saftey

 

Ha!

It is all about force.

Force = mass * accelleration.

As the bike and rider move, their combined mass has a certain amount of force at any given speed. To come to a halt, all that energy has to go somewhere.

When the brake is applied, it causes friction with the rotor. This friction cause the release of the energy moving the bike and rider, converting that energy into heat which the rotors and pads subsequently release to the atmosphere.

This functions nicely so long as the wheel maintains physical contact with the surface underneath, the road. If the tires are two wide, the weight of the vehicle is distributed over a larger area, reducing the mass needed to keep the tire firmly stuck to the road underneath resulting in leaving nice rubber tracks on the road and loss of control of the vehicle. Likewise, tires that are too narrow, will have to much pressure in too small an area and this too can cause in adequate traction resulting in a skid/loss of control.

So there is a careful balance between brake size, tire size, tire compound, and some other factors.

Ultimately, braking distance comes down to how much force has to be released? This is an issue of mass and velocity.

Our motorcycles weigh, what, 500 lbs or so? Adding in the mass of the rider you are looking at something under 800 lbs. Appropriate force has to be "excreted" over the two wheels. It is important that the front brake do most of the work so that the nose of the bike points down, increasing the pressure on the front wheel and keeping it firmly attached to the road. If primary braking happens on the rear, the nose lifts and, bye, bye traction.

With a car, you have much greater mass - something like 4 or more times? Distributed over the 4 tires.

So - the question is - which brakes can create the most heat while maintaining contract and control with the road/vehicle? While the bike may have less mass and thereby force, the car is much easier to control while that force is being dissipated.

 

I dont pass a vehicle unless it is absolutly neccessary. Mostly because I dont want to look like an idiot for having to stop quickly and turn unexpectatly like in the above story.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

While you are at it, teach your self to drop a gear or two at the same time. See what happens when you are zooming along at 50 in fifth and suddenly drop two gears straight and let out the clutch. If you do it right, there'll be a nice jolt and possibly some rubber left on the road as you slow rather dramatically. If you practice this along with applying the brakes, you can dramatically increase your braking power, something very handy in an emergency, but you have to master it first.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

I always engine brake for just that reason - I figure if I make it a habit, I won't have to think about doing it if I ever have to panic stop.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

That's why we ALL, experienced or novice, need to PRACTICE it occasionally. Find a deserted stretch of road; cruise along at your normal pace (55, 60, whatever) then issue yourself a "panic stop" command and see just exactly how quickly you can get stopped. Do it three or four times; practice any time you have the opportunity. It can really save your bacon; if you have the rapid stop part down you can better concentrate on the circumstances that necessitated it.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

There have been a few times when riding that I have had to slow down (always gradually) in a turn. During these times I never use the front brake and just apply as little back brake as possible or engine brake. I was just wondering if I should consider using both brakes at these times or if it is better to stick to just the back?

I figure using the front could cause a bad spin out whereas using the rear will at most just try to straighten out the bike.

 

in a situation such as that you can still use both brakes; but you need to be extra careful with the front and not over-apply it.

If there is gravel or loose sand spread across the turn then even more care is called for of course.

 

Re: Be The Bunny! Safe riding and motorcycle survival threa

tumbleweed_biff, MiCarl is right about the theoretical stopping distance not having anything to do with weight (or mass more specifically). I forgot this and worked it out, the mass in you F=ma equation cancels out because the Force of friction F_fr = c_fr*m*g.

Also, you don't pitch backward when using the rear break, because pitching forward is a result of the torque (force perpendicular to a moment arm) around the cg of the bike. If you apply a backward force where the tire meet the road that always results in a pitching the bike forward, regardless of which tire. If you could make the bike front wheel drive the bike would always pitch up when accelerating, because the F_fr is acting in opposite direction (you can see this in FWD/RWD cars). You use more front brake *because* the bike pitches down when braking and that wheel has more weight on it, not *in order to* pitch the bike forward and keep traction.