Maelochs

here is a simple question----why would only using the front brake stop one faster?

If one applied the front brake for maximum effect .... how would also applying the rear brake reduce the effect of the front brake?


How could using Both brakes possibly be less effective than just using the front? That would imply that using the rear brake Detracted from the stopping power of the front brake.

If any portion of the rear tire is touching pavement and rolling---or even skidding---it is adding friction to the equation. If you lock up the rear (which is obviously bad technique) you might have to ease up the front because the rear end--sliding---will be moving faster than the front end .... but if you are not an idiot and don't lock the rear break (I keep my rear brake looser---I think @79pmooney or whoever said that he leaves a little slack for the same reason) then having two rolling tires being braked increases the friction over having one tire rolling and being braked.

If someone can explain the physics whereby applying the rear break diminishes the effect of the front break I would like to hear it.

Also .... don't come here talking about "tests" without A.) links and B.) explanations. If the guys from GNC cannot manage their brakes, too bad for them .... but the weight transfer forward is going to be a function of the effectiveness of the front brake, and in no way diminished by the application of the rear brake. The friction coefficient of the front tire is not going to change when the rear brake is applied.

Anyone care to explain how Not using the rear brake makes the front brake more effective? And how using the rear brake makes the front brake Less effective?

Is the Earth really flat? Some guy online explained in detail how it had to be .......

big john

Now you've done it.

terrymorse 

Here is how applying the rear brake in a hard braking situation is problematic:

a) Applying the front brake hard unloads the rear wheel, so there is very little force between rear tire and road.
b) With almost no tire-to-road force, even a small amount of rear braking will cause the rear wheel to lock up.
c) With the rear wheel locked up, the wheel will skid, and it tends to "swap ends" with the still-tracking front wheel.
d) This is a bad situation to be in, rider control is close to zero, and a crash becomes very likely. Especially during a turn on a wet road [1].

Rear braking that causes you to lose control — I'd certainly consider that "ineffective".

--
1. Been there, done that. Escaped a worse fate with just a destroyed helmet and some road rash.

tomato coupe

Yes, you can lock up a rear wheel and lose control, but that doesn't mean rear braking is not effective. Up until the point when the rear wheel is totally unweighted, it can contribute braking force -- you just have to be judicious in it's use.

The problem with this line of reasoning is that it can be applied to front brakes as well: "Excessive front braking can cause the rider to lose control and go over the handlebars -- I'd certainly consider that ineffective."

Maelochs

Yeah, I actually mentioned that if you lock the rear wheel you are doing it wrong.

Do it Right.

You cannot say, "This doesn't work because I cannot do it." That is like me saying "Pianos don't work" because I cannot play a piano.

I also mentioned how I leave my back brake a little looser so in a panic stop it doesn't lock. You should have read the post before responding.

As I mentioned you can put full braking force---right to the limit of adhesion---on the front brake and still apply the rear brake .... if you know how to brake. (I hope you learn.)

Maybe get some more time on the bike?

I have locked up the rear wheel notably a couple times in the past couple years Once I did a mad fishtail and actually avoided getting hit by a car because I jumped on the pedals and took off in the suddenly different direction, The other time I just feathered the back brake, regained control and did a small off-road excursion because I missed my turn but it was just a little ride on some grass and I didn't fall or anything---did flat-spot the tire though.

I am sorry if some folks cannot ride a bike. But those are not the people i want to talk to about bike-riding, unless they are asking for lessons or something.

79pmooney

Another way to look at it - in order to have enough weight on the rear wheel to be able to use it for braking, you have to refrain from decelerating fully with your front brake. (It's not hard to show that the maximum stopping power you can get happens just before you flip over the HBs, ie when there is zero weight on the rear tire. Sketch a bike and rider as viewed from the side, guess a location of the center of gravity of the rider, apply the gravity and deceleration vectors and do the math.)

That said, decelerating a little less and having some weight on the rear tire generally works out better. Then a touch of rear brake can be good. But if you have to stop as fast as possible, it's the front that will save your butt.

LarrySellerz

Any amount of rear braking will hinder your ability to use the front brake to it full potential. This talk of using the back brake judiciously in an emergency stop is missing the elephant in the room which is the front brake will do almost all the work and the best thing to do is let it do its job. However my current bike has a poor front brake which cannot offer enough stopping power, so I can apply some of the back brake as well. Its totally not ideal and I would much rather just have a nice front brake.

Also i was the only one who suggested taking off the back brake, and it was only a temporary suggestion to people who are worried about going OTB and feel that they need the back brake to help them emergency stop. A lot of people over rely on the back brake and have no idea how to emergency stop because its not how we were taught to use the brakes. People in this thread are 100% right that using the back brake proactively is a good idea for a number of reasons, and that you should be able to avoid situations where you have to slam the front brake.

tomato coupe

Let me guess ... using the rear brake unweights the front wheel and renders the front brake less effective?

LarrySellerz

No, using the rear means when you slam the front brake your rear tire skids. If it isn't skidding you arent slamming the front brake hard enough or your brake is trash tier. Skidding is probably fine but is less safe. Remember we are talking about emergencies here

tomato coupe

Your cluelessness knows no bounds.

terrymorse 

That depends on what your definition of "effective" is. Of course, rear braking works (is "effective") in many situations. Any experienced cyclist knows that.

But at the upper limit of braking, the rear brake is entirely non-effective, and using it in that situation is problematic.

Knowing how much rear brake to apply becomes natural after some practice with hard braking in many situations, with dray and wet roads. There's an instant feedback from braking the rear too hard, a skid, which a rider learns to avoid. The problem often occurs in a sudden "watch out!" moment, when the rider reactively grabs a big handful of both brakes. This reaction can also be unlearned by practicing emergency braking.

terrymorse 

In a hard braking maneuver, where you are at the limit, using any amount of rear brake is "doing it wrong", because that will lock the rear wheel.

If braking the rear doesn't lock the rear wheel, you weren't at the braking limit.

Kapusta

If someone can’t control the rear brake enough not to skid, than what makes you think they can control the front enough not to go OTB?

A momentary skid is really not that big of a deal. You just let off a tad. Unless you are turning while braking, the rear end is not going to instantly and suddenly come around.

terrymorse 

It is really hard to brake hard enough to send the rider over the bars.

LarrySellerz

Its ok Terry they just don't know how to use the front brake well enough to the point that using the back messes them up. Its a common problem but if they are defensive riders it shouldn't ever negatively impact them. This is a thread about crashing though so they might want to learn how to use the front brake.

LarrySellerz

thats only true if youre used to moving your body weight to compensate

LarrySellerz

True but its not ideal and can be avoided by just not using the back brake during an emergency stop.

livedarklions

55 years of bicycling, and I've never managed to skid the rear wheel except with coaster brakes (we did that for fun when I was a kid)
It is extremely difficult to lock the rear wheel sufficiently to produce a skid with rim brakes. Somebody actually managing to do it with discs?

Trakhak

I suspect that for most of us posting here, we've been riding long enough for our techniques of brake use to have become nearly reflexive.

On my ride today, I decided to pay attention to what I do when I'm braking. I discovered that I apparently nearly always initiate braking with the rear brake and bring the front brake in gradually. Given that that habit has developed over the course of over six decades of riding, I imagine it's proven to be the safest approach.

m.c. 

I do it this way as well, started it in the mid 80s when I got my Schwinn Enduro with rim brakes. I had coaster brakes before that. My first time riding it my dad said, probably as a joke, something about squeezing the front too hard and flipping over.

I don't see any reason to change now.

terrymorse 

Huh? It's trivially easy to lock up the rear wheel with the rear brake. Any type of rear brake.

Did you mean it is extremely difficult to lock the front wheel? Now that is true, it's virtually impossible on hard pavement.

terrymorse 

Nah, it's always pretty darn hard to accomplish an over-the-bars accident when braking. Even when you stay planted in the saddle, rather than push your butt off the back (the standard emergency braking position).

tomato coupe

Effective means the brake assists in stopping the bike.

Just because the rear brake becomes ineffective during a specific phase of an emergency stop, doesn't mean it's not at all effective. Even in an emergency stop, you don't instantaneously transition from full weighting on the rear wheel to zero weighting on the rear wheel. The rear brake can certainly be used effectively during that transition time.

You're arguing that the rear brake is ineffective in an emergency situation where "the rider reactively grabs a big handful of both brakes." That's just a statement that the rear brake is ineffective when used improperly.
Zero weight on the rear wheel is the immediate precursor to going over the bars. So, if it's really hard to send the rider over the bars, then it's also pretty hard to totally unweight the rear wheel.

terrymorse 

My description of when a rider applies too much rear braking in an emergency situation is not "just a statement that the rear brake is ineffective when used improperly".

Using a rear brake in that way is common, and also hazardous.

tomato coupe

You stated that a rear brake can be used effectively with practice. What's preventing people from learning to use the rear brake effectively during an emergency stop?