front/back brake ratio question

[sam_j]

I understand where the brakes are and how to brake, but my question is if 75% fo the stopping power comes from the front, when applying both brakes, do you apply pressure on the front and back break evenly giving you a 75/25 braking ratio by the size of the brake discs? or do they have an even equal amount in stopping power, leaving you to "feel" the amount of pressure to apply the 75% up front and the 25% on the back

[Sev]

Uhhhhh, the weight shifts forward when you're stopping.. so the front brake provides 75+% of your braking power. If you feel the back wheel lift up, then you've got 100% braking in the front.

Basically it depends upon how well you use your brakes, and how you shift your weight, plus what kind of brakes you have front and rear.

It isn't a set ratio.

[pseudopod]

The amount you push and pull on the brakes varies motorcycle to motorcycle. It's hard to say whether you're pushing your foot down as hard as you're pulling your hand in. The best way to figure out the proper threshold is to practice your quick stops. If the rear tire is skidding you know that was too hard. If the front tire is skidding then you need to let off a bit on that too. BTW if you are practicing your quickstop and the rear tire begins skidding, the correct technique is to keep skidding it until you stop. Otherwise you risk a high-side.

[J.R. Bob Dobbs]

In my experience, pseudopod is entirely correct.

[Motofiend]

This question is sort of on topic:

When practicing quick stops what is a good stopping distance to aim for?

for example at 15mph, 30mph, 45mph, ect..

[J.R. Bob Dobbs]

I've only got about 7000mi under my belt so take this for what its worth.

When I practice quick stops I don't pay much attention to stopping distance. I do it in a large vacant parking lot, get up to whatever speed I'm trying for, hold that speed, and pick a line on a parking space as the point where I start braking.

When I cross that line, I pull the clutch and apply heavy braking (mostly front) and concentrate on getting maximum deceleration without skidding a tire. I can feel the front of the bike getting a little "rubbery" at the threshold of a skid and try to keep it there without regard to distance traveled. I bring on a little more rear as the bike gets closer to stopping when I know I can handle a small skid. As the speed approaches zero, I let up on the front and go hard on the rear and put left foot down.

Once in a while I'll also intentionally skid the rear (just as I'm about stopped) to remind myself where the threshold is, but I'm afraid to try skidding above say 15mph, once in a while the rear does slide sideways, but I've not had the bike get away from me yet.

[macdaddy]

Nice answer. The minimal distance will depend on more than just speed - includes pavement type & temperature, tire compound & temp, weight of bike and rider. As long as you can lock up both the front and rear brakes, it shouldn't depend on your brake pads. What you are shooting for is "threshold braking" - braking as hard as you can without skidding the tires. It really is something that you have to get a feel for, and the way to do this is not during regular street riding, but in a parking lot or deserted stretch of road. You are trying to do manually what ABS does automatically - apply the brakes harder until the tire starts to slip just the faintest amount, then feather back off the brake, then apply the brakes harder until the tire starts to slip, then back off... You don't want the tire in a full skid, and the "rubbery" feeling the previous writer mentioned is a pretty good description of the tire just starting to slip.

That being said, the MSF course does have some stopping distance maximums for different speeds - any instructors care to share them?