KindredGhost

http://www.fmq.qc.ca/pdf/amorce-freinage_eng.pdf

I'm not sure if it's been posted here before (probably has but it's still a good read for the n00bs). Anyway, it's braking techincal data compiled by real world tests on a cbr929 and a cruiser.

What shocked me the most is that the 16th fastest stop (from 62.xxx mph) was by someone who only used his front brake! They don't recommend that technique though... Also downshifting while emergency braking added a few feet as well... I always thought it'd help you improve your stop distance... go figure... interesting read I thought I'd share with you all...

KG

Keep the rubber side down fellas...

truepath

great tech info.....thanks

RickB

+1

FL02SupaHawk996

Good info KG!

Thanks,
Rick C.

RCVTR

Good stuff.
Braking force is limited by the point at which the rear wheel lifts off the ground. At maximum braking, the rear brake does nothing except make the rear wheel slide. Racers use it more to control the attitude of the motorcycle and to weight the front end, trail-braking on corner entry, than deceleration.

the first thing I learned on the track, when I was being followed was to watch the throttle application. The second thing was, stay off the damn rear brake.

kfkraenz

Very intresting. I know for a fact that I get better stopping distance with just the front brake. The only reason I can figure is that by focusing on front only I get better performance out of the front (and not distacted by the rear brake). After reading this, I may start trying to use both for a while to make it habbit to use both and then re-evaluate stopping distance.

Josh

That's a good read. Makes me feel good about my regular rear brake use in conjuction with the fronts.

RCVTR

I should qualify that statement.

The braking force is limited by the rear wheel lifting if:

1. there is enough traction at the front tire that it is not the limiting factor. In situations of limited traction, the rear brake will help

2. the front brake is applied gradually enough that the weight transfer occurs to increase the load on the front tire before the maximium braking force is applied.

3. the braking is done in a straight line.

killer5280

They don't recommend using only the front brake for maximum deceleration? I never go near the rear when braking really, really hard.
Braking force completely overwhelms any stopping power you would get from downshifting while stopping hard; downshifting while doing max braking, at least on the Hawk with its non-slipper clutch, just increases the chance that the back will lock up.
Remember the "unintended acceleration" cases of twenty or more years ago where people claimed that their cars accelerated out of control even though they were stomping the brake pedal? Of course that's impossible because braking force is greater than driving force. It turns out that people were stomping the gas pedal, but thinking they were stomping the brake.

lazn

http://www.stevemunden.com/braking.html

RCVTR

One more caveat.

the forward roll (stoppie) limitation on braking force assumes a sportbike designed to go araound a racetrack fast. They are designed with a high center of mass, so the head tube angle steepens dramatically on the brakes making them turn in to corners well. I recently read a description by Jerry Burgess of how they raised the seat height on Valentino's YZR-M1 to make it turn better.

a cruiser is an entirely different story. There is no way your going to lift the rear wheel off the ground on the brakes. In that case, there is no doubt that the rear brake will shorten stopping distance.

HisHawkiness

Just read that article in SportRider today, They actually raised the ride height of the bike to promote better weight transfer during braking because Rossi was having problems with locking the front tire.

The training wheels are hillarious....."both equipped with outriggers to allow the riders to reach or surpass the braking limits of the
motorcycles."

RCVTR

You're right. I hate it when my imagination exceeds my recollection...


The weight transfer has a combined effect. I try to keep it all straight. Motorcycle dynamics are very complex, sometimes indistinguishable from magic.

Shortlived99

I use both always. I lock the rear brake and dirt bike it sometimes. If u gotta stop, u gotta stop. Havent high sided yet. Hopefully all the practice will pay off one day.

Racers dont use rear brakes??? Your insane...

RK1

"I remember all three times I used it (the rear brake) in a race, because I crashed every time!... It takes a conscious effort to keep my right foot on the ball of the footpeg so I stay away from the pedal."


Kevin Schwantz

RK1

I understand that some racers use the rear and some don't. My guess is that for street riding you could train yourself and practice using both brakes for effective emergency stopping, but otherwise, if you get in the habit of using both brakes all the time for "normal" stopping, when you run into a "holy ****" emergency and stomp both brakes, you'll lock up the rear as soon as it get light. And then run the risk of either losing the rear end or letting up on both brakes at the same time.

I'm glad my VTR has a rear brake so I can hold the bike in place when stopped on a hill, take my hands off the bars and sit up for a minute.

RK1

I haven't read the whole paper but went back and scanned it again.

I like the recommended sequence on page 15;

Completely close the throttle
Apply the rear brake
Place the bike vertical
Brace arms amd legs
Straighten torso
Position fingers and feet
Apply appropriate pressure to the front brake.

Excuse me, but long before you've completed the check list of six things to do BEFORE applying the front brake, you and your bike will have bounced off whatever object you were hoping to avoid. Or fallen down and slid into it because you forgot to put on your training wheels before locking up the rear wheel.