Rear Brake Usage during Braking

[shaddix]

Originally Posted by slartidbartfast

Since when was this only about sport bikes?

...and since when could you brake hard enough to achieve close to 100% weight transfer to the front wheel on any bike when braking over manhole covers, painted stripes, in the wet, etc.? (i.e. real-world street riding conditions)

You didn't specify only cruisers in your post, but mentioned police motorcycles. I thought it appropriate to comment on that. When I took my MSF class, they told me the front tire provides at least 70%. I asked then how far up does it go, and my instructor stated it could be all the way to 100% depending on the bike if the rear tire is off the ground. And this guy is an experienced rider coach who participates on this forum.

For braking over paint stripes and manhole covers, if I recall an article that I read on the matter, you'll get shorter stopping distances by just holding the brake and let the front tire slide over it instead of trying to let off the front brake so it doesn't lock when contacting the slicker surface. A bit counterintuitive, but it makes sense because of the difficulty in precisely timing the release and reapplication of the brake when passing over the surface hazard. On wet pavement alone, I would say it depends on the bike of course, I've seen a bike do a stoppie on wet pavement, so just being wet doesn't automatically mean the front wheel will skid before lifting the rear.

I have not tested this on my bike, I expect with my shitty shinko tires, I would not be able to do a stoppie on wet pavement.

[slartidbartfast]

Originally Posted by shaddix

You didn't specify only cruisers in your post, but mentioned police motorcycles.

The original post was about a novice rider whom we later learned rides a dualsport (IIRC) - a short wheelbase bike with stoppie potential in the right hands, but with long travel suspension so needing progressive brake application to reach maximum safe braking

I thought it appropriate to comment on that. When I took my MSF class, they told me the front tire provides at least 70%. I asked then how far up does it go, and my instructor stated it could be all the way to 100% depending on the bike if the rear tire is off the ground. And this guy is an experienced rider coach who participates on this forum.

For braking over paint stripes and manhole covers, if I recall an article that I read on the matter, you'll get shorter stopping distances by just holding the brake and let the front tire slide over it instead of trying to let off the front brake so it doesn't lock when contacting the slicker surface. A bit counterintuitive, but it makes sense because of the difficulty in precisely timing the release and reapplication of the brake when passing over the surface hazard. On wet pavement alone, I would say it depends on the bike of course, I've seen a bike do a stoppie on wet pavement, so just being wet doesn't automatically mean the front wheel will skid before lifting the rear.

I have not tested this on my bike, I expect with my shitty shinko tires, I would not be able to do a stoppie on wet pavement.

Letting either tire skid over a short slick area may be ok if:

1. it is indeed a short area
2. you are not leaned over much (or maybe at all)
3. you are not at maximum braking for the higher friction surface - otherwise, the front wheel will continue to skid rather than resuming turning when you get off the slick bit

The issue, of course, is that in most circumstances, "maximum" braking on the street is not the same as maximum braking under controlled conditions. This is because of the variability (actual or potential) of a typical road surface and the severe consequences of "laying it down" while trying to slow it down. i.e. even in an emergency situation, you probably don't want to be braking at 10/10 on the street. Unless you are absolutely sure you have those ideal, predictable, high traction conditions, you need to leave a margin to allow for all those variabilities so you don't dump it (which would be worse than not braking so hard).

If you find yourself needing to emergency brake on the street when the road conditions and visibility are even close to being as good and predictable as on the track, you are not paying sufficient attention to your riding anyway.

Clean, wet pavement supposedly has about 80% of the grip of dry pavement - easily enough to do a stoppie on the right bike. However, slicker areas are generally MUCH slicker in the wet and the available traction is harder to gauge in advance so you quite rightly would not want to try it.

[shaddix]

Originally Posted by slartidbartfast

The original post was about a novice rider whom we later learned rides a dualsport (IIRC) - a short wheelbase bike with stoppie potential in the right hands, but with long travel suspension so needing progressive brake application to reach maximum safe braking


Letting either tire skid over a short slick area may be ok if:

1. it is indeed a short area
2. you are not leaned over much (or maybe at all)
3. you are not at maximum braking for the higher friction surface - otherwise, the front wheel will continue to skid rather than resuming turning when you get off the slick bit

The issue, of course, is that in most circumstances, "maximum" braking on the street is not the same as maximum braking under controlled conditions. This is because of the variability (actual or potential) of a typical road surface and the severe consequences of "laying it down" while trying to slow it down. i.e. even in an emergency situation, you probably don't want to be braking at 10/10 on the street. Unless you are absolutely sure you have those ideal, predictable, high traction conditions, you need to leave a margin to allow for all those variabilities so you don't dump it (which would be worse than not braking so hard).

If you find yourself needing to emergency brake on the street when the road conditions and visibility are even close to being as good and predictable as on the track, you are not paying sufficient attention to your riding anyway.

Clean, wet pavement supposedly has about 80% of the grip of dry pavement - easily enough to do a stoppie on the right bike. However, slicker areas are generally MUCH slicker in the wet and the available traction is harder to gauge in advance.

Thanks for the excellent information. This is why I'm not willing to ride in the rain without ABS. I need to trade the DR in soon

[Wraith Rider]

Originally Posted by crofrog

The track is the only real place we have to look at what the machines and riders are capable of.

It's not. It's no "real" place. The track is very artificial, with trained/experienced riders, under perfect, defined, and stable conditions.It's very far away from what awaits you out on the street. I said it before, me on my bike would not even be close to reach the stopping distances the guys on the track reach, IF I wouldn't use my rear brake, even if I brake on the edge of physics.

Originally Posted by randyo

I am less than inspired by the performance of ABS on ice, probably cause the vehicles Ive driven had primitive ABS compared to what is available today.

I crashed on ice without touching the brakes of my motorcycle, just because of a bump in the road. I don't think there's something to criticize about motorcycle ABS on ice, while you have only about a tenth of regular traction left to work with.

[crofrog]

Originally Posted by Wraith Rider

It's not. It's no "real" place. The track is very artificial, with trained/experienced riders, under perfect, defined, and stable conditions.It's very far away from what awaits you out on the street. I said it before, me on my bike would not even be close to reach the stopping distances the guys on the track reach, IF I wouldn't use my rear brake, even if I brake on the edge of physics.

You wouldn't reach it with the rear brake either it sounds like.

[Wraith Rider]

Originally Posted by crofrog

You wouldn't reach it with the rear brake either it sounds like.

I DO reach what is technically possible on my bike. What is better than most experienced riders reach. What is better than most or all beginners reach.

[PhilB]

Originally Posted by dwoodward

Aw, hell. Let's throw some actual research at this

Ignoring the focus of this one, which is ABS / CBS, pay attention to stopping distances of front / rear / both.
http://www.msf-usa.org/imsc/proceedi...ngdistance.pdf

This one focuses on technique:
Task analysis for intensive braking of a motorcycle in a straight line
http://www.msf-usa.org/imsc/proceedi...ingSystems.pdf

IDEAL SEQUENCE
These figures indicate that the ideal sequence for the most effective emergency braking possible is to successively
close the throttle, apply the rear brake, apply the front brake and declutch completely.

Something nobody's argued about:

A FEW SECONDS OF AUTOMATISM
We quickly realized during these tests that the load imposed on the rider during hard braking is immense. An emergency stop from 100 km/h lasts more or less four seconds; basically, one second for reaction and stabilization and three seconds of braking. During these four seconds the rider undergoing considerable physical stress acts in a conditioned manner. In an emergency, the rider performs unconsciously but more quickly and less well what he does habitually in more normal situations.

BRAKING THROUGH HABIT
Pierre Savoie, chief instructor of driver training for BMW Canada, explains the matter by saying, “According to Dr. Bruce Lipton of Sanford University in California, our conscious mind can process 2,000 bits of information per
second, while our subconscious can process 4,000,000,000. It’s not necessarily limited to reflexes, but to the deeply rooted habits of human beings.”

INGRAINED HABITS
In our opinion, the only way for a rider to achieve true proficiency in straight-line emergency braking of a motorcycle is to practise long enough and hard enough to make the procedure a matter of habit.

Yay!

PhilB

[catweasel67]

Originally Posted by Wraith Rider

I DO reach what is technically possible on my bike. What is better than most experienced riders reach. What is better than most or all beginners reach.

if you've reached the technical limits of your bike you should really be in moto GP etc.

I fully expect to ride for a lifetime and still be no where near the limits of my bike, and that's after track days etc

[PhilB]

Originally Posted by catweasel67

Your response provoked me to fact check, something you don't do.

http://www.motogp.com/en/MotoGP+Basics/brakes

they use rear brakes..

And guys, rear wheel braking is not a question of opinion...it's physics....you've heard of that right?

There simply is no argument here and yet..people try. I guess most of you are bored?

Yay some more!

PhilB

[PhilB]

Originally Posted by slartidbartfast

F**k me! I think he might finally be getting it.

Instead of comparing street riding by a novice to track racing, why not look at what the most experienced and best trained street riders are doing - Wouldn't that make more sense? Go and talk to a police motorcycle mechanic and ask him if he sees any wear in their rear brakes. Talk to a police motorcyclist and suggest that he should not be using his rear brake because you don't do it when you play on the track - See what he has to say about that. Then try to out ride him on the street (with or without a rear brake). If you survive, you'll have your metaphorical ass handed to you.

Use both brakes! It's what every real expert in street riding teaches, every street riding curriculum includes and every experienced street rider practices

+1! This.

PhilB

[PhilB]

Originally Posted by crofrog

So I'm guessing you don't have any high performance riding time?

We've already been over that, as well as over why that isn't even very relevant. To "ignore" with you. I have no room in my life for ill-behaved louts with poor logic skills, a weak grasp of reality, and marginal-at-best literacy.

PhilB

[Wraith Rider]

Originally Posted by catweasel67

if you've reached the technical limits of your bike you should really be in moto GP etc.

I fully expect to ride for a lifetime and still be no where near the limits of my bike, and that's after track days etc

I shouldn't, because there's more than computer assisted braking to MotoGP. On the other hand it's quite simple to master computer assisted emergency braking without doing any track days.

Hell, modern technology realy helps a lot to not having to invest a lifetime to learn how to use your bike up to (some of) its limits.

[anotherguy]

It's easy to pass the limits of a new bike. If it wasn't no one would fall off them. Riding well and passing limits don't necessarily occur simultaneously.

[PhilB]

Originally Posted by anotherguy

It's easy to pass the limits of a new bike. If it wasn't no one would fall off them. Riding well and passing limits don't necessarily occur simultaneously.

He did say "reach" them, not "pass" them. Yes, it's easy to pass the limits. It's hard, and takes riding well, to reach the limits without passing them.

PhilB

[anotherguy]

Originally Posted by PhilB

He did say "reach" them, not "pass" them. Yes, it's easy to pass the limits. It's hard, and takes riding well, to reach the limits without passing them.

PhilB

I suspect you understand a jest.