The smell of burning rubber

[HotRodZilla]

You guys do realize that properly working ABS allows the tires to stop, but only for very short intervals? I used to determine vehicle speeds by skid marks left by cars with ABS, all the time. I even got into a huge pissing match with a civil attorney who tried to claim I was full of shit, because his clients car with full ABS wouldn't leave skids. It did, and they do. They look like a ladder: tons of faint black lines. Remember, until the tire locks up, the computer doesn't know how much traction there really is, so they lock, release, lock, release, repeat, until the vehicle stops or the brake pressure is reduced. Smelling rubber after a hard ABS induced stop is perfectly normal, as is soiled underwear in some cases!

Not wishing into get into a p*ss*ng match, but I think you will find that modern ABS systems are a little more sophisticated than those you were dealing with, and don't wait for the wheel to stop before releasing the brake. They detect that one wheel is turning significantly slower than the other, or that a wheel is decelerating at a rate greater than is normally possible.

Operation and cycling rate are much faster and more subtle (though generally still obvious) than early systems.

A quick web search finds many sources, one such is https://auto.howstuffworks.com/auto-parts/brakes/brake-types/anti-lock-brake1.htm, I quote a couple of paragraphs (my emphasis):

The controller monitors the speed sensors at all times. It is looking for decelerations in the wheel that are out of the ordinary. Right before a wheel locks up, it will experience a rapid deceleration. If left unchecked, the wheel would stop much more quickly than any car could. It might take a car five seconds to stop from 60 mph (96.6 kph) under ideal conditions, but a wheel that locks up could stop spinning in less than a second.The ABS controller knows that such a rapid deceleration is impossible, so it reduces the pressure to that brake until it sees an acceleration, then it increases the pressure until it sees the deceleration again. It can do this very quickly, before the tire can actually significantly change speed. The result is that the tire slows down at the same rate as the car, with the brakes keeping the tires very near the point at which they will start to lock up. This gives the system maximum braking power.

I do, however, remember my first car with ABS. When that operated for the first time, I thought the car would shake itself to bits, more frightening than the bus that had cut across in front of me! I suspect that one did allow the wheels to stop.

(For anyone who still doubts the value of ABS, I'd suggest they read this ABS comparison test, done back in 1992.)

I think we're saying the same thing, just with slightly different approaches. I was keeping it very basic, because I'm pretty rusty, and I didn't want to have to type a whole bunch of technical shenanigans that your article may have hit upon. What I'll say is this: The tire goes into that massive deceleration phase at impending lockup. If it didn't, there would be no risk of lockup. When the tire starts that rapid deceleration that puts it out if phase with the vehicle or other tires, there will be some slip, before the ABS kicks in and eases the pressure. Newer systems are faster than the older ones, but most of the principles are still relevant. It doesn't take much loss of traction to heat up a tire and cause a burning rubber smell. This same ABS activation is why a tire will be significantly warmer after a hard ABS stop.

 

[Mortenk]

This is quite normal. As you all say, the rear wheel must spin slower than the front wheel before ABS kicks in, so you have a lot of friction between rubber and road = heat and burned rubber. The wheel doesn't have to stop rotating for this to happen - just rotate slower than the front. If you did this every time you stopped, I can guarantee that your tires would wear out in a heartbeat - and where does it go? Up in smoke...

Road conditions are important, but another reason this happened could be that you applied the brakes too quickly. When riding at constant speed, you don't have a lot of weight on the front wheel, hence the footprint is small. In order to build up braking power, you need to gradually shift weight to the front wheel, which increases the footprint and gives you more friction to play with. This is done by gradually increasing braking power, rather than hit the anchor...many crashes have happened because riders brake too sudden, rather than gradually increasing brake pressure. ABS saves a lot of these nowadays though...

Finally: there is no such thing as front brake or rear brake only on this bike. Whether you use the foot or the hand, you are applying both brakes. I am very impressed by the braking power when I use the pedal only, but that's obviously because it's activating the front brake significantly. Happy riding all.

 

[mcatrophy]

...
Finally: there is no such thing as front brake or rear brake only on this bike. Whether you use the foot or the hand, you are applying both brakes. I am very impressed by the braking power when I use the pedal only, but that's obviously because it's activating the front brake significantly. Happy riding all.

Front lever does nothing at the back, the only link is from back pedal to front, and then not very much.

 

[Mortenk]

...

Finally: there is no such thing as front brake or rear brake only on this bike. Whether you use the foot or the hand, you are applying both brakes. I am very impressed by the braking power when I use the pedal only, but that's obviously because it's activating the front brake significantly. Happy riding all.

Front lever does nothing at the back, the only link is from back pedal to front, and then not very much.

Ah - interesting! I'm new to the FJR (coming from the ST where front lever impacts the rear brake and vice versa)...thanks for the clarification. I do feel that the pedal has a great stopping power though, so it must be pushing hard on the dedicated set of front pads...

 

[Redfish Hunter]

As our English friend says, the front FJR brake does nothing for the rear. MortenK, on your old ST the left front caliper compresses a secondary master cylinder that actuates two of the pistons on the rear caliper. The FJR is not as complicated.

I 100% agree with 'Zilla. Tires can slip enough to leave a burnt rubber mark and still be turning. As I said before, I feel that the threshold on the newer ABS is allows more braking power. The front and the rear can be "slipping" enough to heat the surface rubber to the point of releasing a burning rubber smell.

I think Mcatrophy should test our theory (theories). He can set the test up however he wishes but I would suggest a beginning speed of at least 100mph. Intermittent patches of sand, gravel and dust would add some fun to the experiment.

Just Kidding old friend. Stay safe.

 

[mcatrophy]

...I 100% agree with 'Zilla. Tires can slip enough to leave a burnt rubber mark and still be turning. As I said before, I feel that the threshold on the newer ABS is allows more braking power. The front and the rear can be "slipping" enough to heat the surface rubber to the point of releasing a burning rubber smell.

I think Mcatrophy should test our theory (theories). He can set the test up however he wishes but I would suggest a beginning speed of at least 100mph. Intermittent patches of sand, gravel and dust would add some fun to the experiment.

Just Kidding old friend. Stay safe.

I think I've already done that test (but I won't actually admit to 100mph :aaevil: ).
Over the last nearly 12 years of riding FJRs, I have tested the ABS on each of my FJRs, it's something I do as a matter of course (albeit usually on a damp road - I do live in the UK, after all :blinksmiley: ).

I ride on a more-or-less daily basis and have had many "surprise" braking episodes that have reached ABS activation, some of them actually on a dry road.

All I can say is that, in all those episodes, I've never before experienced that smell, hence this thread.

Maybe it's because they rarely end in a full stop, and this one did?

 

[Spud]

I've also done a lot of practice "panic stops" but only once did I smell the burning rubber after my deer strike. However it works, ABS does work and training yourself to completely clamp down when needed can save you in a bad situation. I wouldn't want another street bike without the feature.

 

[08FJR4ME]

guilty

oh the shame. Been there done that.

Zilla's going to have to come and arrest my ass and put me in jail for 8 months.

Dave

 

[Uncle Hud]

Spud posted: ... I wouldn't want another street bike without the feature.

Convinced my wife to swap her '05 SV650 for a '17 FZ07 mostly to get ABS. (The working speedometer and brake light were just considered "nice to have".)

 

[HotRodZilla]

:blushing: guilty :blushing: oh the shame. Been there done that.
Zilla's going to have to come and arrest my ass and put me in jail for 8 months.

Dave

Don't knock it. It's a nice break. 3 meals a day, plenty of rest, exercise, color TV, a nice library, better weight room than most high school football teams, and all the shower sex you want. Someone else washes all your clothes and cooks your meals. It's like a cruise, without the water, and maybe some crying during certain activities.

 

[tdw]

Admittedly I'm a little late to the discussion; but, I think the underlying thread of emergency braking is important. Further, I'll apologize in advance as I think I'm going to be hijacking the discussion somewhat.

Rhetorical Question: Do you practice emergency braking?

Clearly some of you do based on the comments. I personally think it's important to practice all our handling skills regularly which is one reason why I try to take a course every year.

Coming back to emergency braking, the instruction you receive at Advanced Rider Training (ART) teaches you that you will stop much more quickly (1) using both brakes & (2) without engaging the ABS. To that end, they teach you to progressively apply the brakes, not simply hammer them, as Mortenk wrote in his post. They teach you to count one, two as you apply the brakes to consciously apply them progressively. During the count of one you are initially slowing the bike and transferring the weight to the front tire so that as you then count two and apply them aggressively, the load on the front keeps the wheel rotating so that you don't lock it and engage the ABS.

One of the reasons I'm bringing this up is that I've wondered about the ABS technology on the FJR. On my old '04 RT I could apply the brakes hard using this technique without engaging the ABS. On that bike it was obvious based on the feedback if the ABS was engaged.

On my new to me '15 FJR, I swear despite my best efforts I keep engaging the ABS. Even before retaking the ART course this past weekend, I tried practicing the emergency braking a few times. Then on the course we practice all afternoon on the second day. While I'm stopping quickly and applying the brakes progressively, I can't help but feeling I'm engaging the ABS. There's no pronounced feedback like there was on the RT but there is a faint shudder that leaves me thinking I keep engaging the ABS.

Based on this, and some of the description of the ABS system in this thread, I'm left wondering if maybe I am engaging the ABS but that the technology has progressed to the point that the difference in stopping distance between engaging or not engaging it in hard braking is minimal. Can anyone comment on this?

As an aside, part of the skill taught in ART is to not actually stop the bike but to bring it to a slow walk and proceed to navigate around obstacles. To that end, they have you braking hard then have a course set up with multiple tight turns, keyholes, figure eights ... so that you learn to control the bike without having to put your foot down. The idea is that you'll likely have to brake hard to avoid a collision then have to navigate the carnage to avoid becoming a part of it.

 

[Uncle Hud]

I believe that ABS braking provides shorter stopping distances than non-ABS braking, in all conditions and all types of pavement.

This is only my opinion, although I've read extensively about it. Too lazy at the moment to look up statistics.

 

[HotRodZilla]

I believe that ABS braking provides shorter stopping distances than non-ABS braking, in all conditions and all types of pavement.
This is only my opinion, although I've read extensively about it. Too lazy at the moment to look up statistics.

You're absolutely correct. Once a vehicle goes into a slide, or skid, the coefficient of friction drops to nearly zero. Obviously, depending on surface and type of slide. The usual COF on a new paved road is around 6.0 to 6.5. So, ABS maintains the ability to continue to slow, without losing traction. The loss of COF is the reason a sliding tire cannot steer. It needs friction to enable the direction change. The less friction we have, the longer it takes to stop.

 

[Uncle Hud]

^^^^ Dayum. 'Zilla knows physics? Startling.

 

[mcatrophy]

^^^^ Dayum. 'Zilla knows physics? Startling. :coolsmiley02:

If I were you, I wouldn't get too excited about HRZ's knowledge of physics. His suggestion of a coefficient of friction of 6 to 6.5 is somewhat fanciful .

 

[HotRodZilla]

^^^^ Dayum. 'Zilla knows physics? Startling. :coolsmiley02:

If I were you, I wouldn't get too excited about HRZ's knowledge of physics. His suggestion of a coefficient of friction of 6 to 6.5 is somewhat fanciful .

Sorry Mac. I've been at this a long time. A COF of 6.0 on a newly paved road here in the US is a common number. Concrete roads are even better. I've used that as a base, before even measuring the road, and then doing it again, after measurement. Even when we're off a bit, we're usually within a few MPH.

 

[mcatrophy]

^^^^ Dayum. 'Zilla knows physics? Startling.

If I were you, I wouldn't get too excited about HRZ's knowledge of physics. His suggestion of a coefficient of friction of 6 to 6.5 is somewhat fanciful

.

Sorry Mac. I've been at this a long time. A COF of 6.0 on a newly paved road here in the US is a common number. Concrete roads are even better. I've used that as a base, before even measuring the road, and then doing it again, after measurement. Even when we're off a bit, we're usually within a few MPH.

Please define what you mean by COF. I presumed you meant "Coefficient of Friction" - the usual term to define gripping potential - which I learnt as:

(Friction force) / (Normal force)

where 1.0 is considered about the best normally possible; a COF of 1.0 would allow a retardation of 1G, which is the maximum you could ever expect on a real road.

If you mean something else, then I certainly apologise, but ask that you don't use acronyms liable to confuse we dumbos (I'm very easily confused

).

 

[HotRodZilla]

^^^^ Dayum. 'Zilla knows physics? Startling. :coolsmiley02:

If I were you, I wouldn't get too excited about HRZ's knowledge of physics. His suggestion of a coefficient of friction of 6 to 6.5 is somewhat fanciful .

Sorry Mac. I've been at this a long time. A COF of 6.0 on a newly paved road here in the US is a common number. Concrete roads are even better. I've used that as a base, before even measuring the road, and then doing it again, after measurement. Even when we're off a bit, we're usually within a few MPH.

Please define what you mean by COF. I presumed you meant "Coefficient of Friction" - the usual term to define gripping potential - which I learnt as:

(Friction force) / (Normal force)

where 1.0 is considered about the best normally possible; a COF of 1.0 would allow a retardation of 1G, which is the maximum you could ever expect on a real road.

If you mean something else, then I certainly apologise, but ask that you don't use acronyms liable to confuse we dumbos (I'm very easily confused :mda: ).

Haha...IDIOT! I need more sleep. This dammed grave shift is making me dumber, and I didn't really have that much wiggle room.

How's about .6 and .65. NOT, 6 and 6.5. However for our math purposes, for some reason we do the dammed formulas as 6 or 6.5 and then multiply by .10. No idea why that is done, and I talk about it that way because that's how I was trained to do it 21 years ago. Since everyone else got the same dumb training, if freaks them out when I do the math and skip that step.

I'm glad someone is watching out for my BS shenanigans! Lol

 

[mcatrophy]

...How's about .6 and .65. NOT, 6 and 6.5. However for our math purposes, for some reason we do the dammed formulas as 6 or 6.5 and then multiply by .10. No idea why that is done, and I talk about it that way because that's how I was trained to do it 21 years ago. Since everyone else got the same dumb training, if freaks them out when I do the math and skip that step.

I'm glad someone is watching out for my BS shenanigans! Lol

Glad that's what is going on, and always glad to be of help .
I suppose you can't really expect the average policeman to be able to deal in decimals -_- .

 

[Uncle Hud]

Uncle Hud posted: ^^^^ Dayum. 'Zilla knows physics? Startling.

OK, maybe he doesn't. Reassuring.