braking distance

[ionbeam]

Here are a few other data points for braking distances (plus some bonus data too).

 

[Checkswrecks]

From an engineering point, the data in this case is pretty much meaningless. The stopping distances don't differ by an order of magnitude and are really down to variables. As others have pointed out, without normalizing the variables that will change even the same bike from day to day, let alone these different bikes, the comparison that you are trying to make is invalid. Even if these are the best numbers available, the problem is that you're trying to over-extrapolate their meanings.

From a more realistic aspect, any of the bikes mentioned in this thread can lock up either wheel. Take the numbers as guidance that the bikes you're interested in stop roughly similar and go from there. The biggest variable and the only one that counts is how well YOU do on each bike.

Remember what Von Braun said: "One good test result is worth a thousand expert opinions."

Enjoy your experimentation!

Bob

 

[RonBB]

I must admit that I was somewhat surprised when I read the brake data in the article. On my 05 I think I could beat that stopping distance and I always felt that the rear ABS kicked in a bit early. The 07 certainly feels to be quicker in the stopping than the 05 (linked brakes?). At any rate I don't think the distances shown were representative of either FJR that I have owned. I believe the other posted data on the forum to be more accuate. Ron

 

[JimLor]

Is there any way to adjust the sensitivity of the ABS, or in other words, adjust when it kicks in? Although these are the best brakes I've ever had on a bike (yes, my first bike) I too think the rear ABS kicks in kind of early. In fact, I adjusted by rear brake pedal down a bit to make it easier to modulate pressure.

 

[ionbeam]

Is there any way to adjust the sensitivity of the ABS, or in other words, adjust when it kicks in?

Basic ABS: The ABS system monitors wheel speed and chassis speed, when the wheel speed becomes too low vs chassis speed (known as the slip ratio), the ABS actuates and begins to release brake fluid pressure to the rear caliper. Usually the magic trip point is considered to be a 86% slip ratio (also known as slip angle) = impending wheel lockup. This is a software calculation, therefore not adjustable. If your ABS actuates, the wheel is at the edge of skidding so you wouldn't want to adjust the trigger point any further.

The noise and pulsing you feel from the ABS system has nothing to do with actual ABS operation, it is an 'engineering feature' added to alert the rider/driver that the ABS system has been activated!

 

[biggjohn]

Is there any way to adjust the sensitivity of the ABS, or in other words, adjust when it kicks in?

Basic ABS: The ABS system monitors wheel speed and chassis speed, when the wheel speed becomes too low vs chassis speed (known as the slip ratio), the ABS actuates and begins to release brake fluid pressure to the rear caliper. Usually the magic trip point is considered to be a 86% slip ratio (also known as slip angle) = impending wheel lockup. This is a software calculation, therefore not adjustable. If your ABS actuates, the wheel is at the edge of skidding so you wouldn't want to adjust the trigger point any further.

The noise and pulsing you feel from the ABS system has nothing to do with actual ABS operation, it is an 'engineering feature' added to alert the rider/driver that the ABS system has been activated!

I can understand how the ABS would get front and rear wheel speeds, but how does it get chassis speed?

John

 

[madmike2]

I can understand how the ABS would get front and rear wheel speeds, but how does it get chassis speed?
John

Possibly the ECU is reading the speedometer sensor at certain intervals (once per second, 1/2 second, 3 seconds?) and comparing that to wheel lock-up sensor readings. :dntknw:

 

[ionbeam]

I don't know this for an absolute fact, but a really good guess is that the ABS unit uses a suspended mass accelerometer to keep track of G Forces. I've got a G-Tech performance analyzer stuck to the dash of my car that I use to help tune my car for the track and it uses an automotive grade accelerometer. These days accelerometers are cheap enough to use in toys like my G-Tech and probably more accurate (number of decimal places) than required for an ABS system. FWIW, my 2 ton car goes from 60 to 0 in 110 feet and it's a wild ride.

 

[markjenn]

There is no way it would be a deal breaker, and there are a lot of variables involved, but if you take MCN at face value, then you have to say that the ABS system on the FJR might be a bit sub-par vs. the competition and might possible contribute to somewhat longer stopping distances. Tires are the big factor in stopping distances, but the ABS system can make a contribution. Having said this, I'll still take a slightly clunky ABS system over no ABS on a heavy all-weather touring bike as there is no way I'm going to safely approach threshold braking consistently in a random emergency situation.

With the news that the 2008 gets a new ABS system, I'm just pleased as punch that Yamaha continues to refine and develop the model, even on a year-by-year basis. This is refreshing in a category of motorcycles that has tended to lay stagnant year after year between way-too-widely-spaced major model revisions. It appears Yamaha's mantra with the FJR is continual refinement and that's great. All the motorcycles in this category are so good, that top dog will be the one that has the rough edges polished. Yamaha did this with the heat problem and now appear to be doing it with the ABS sytem. Bravo to Yamaha.

- Mark

 

[jestal]

Another way ABS systems can determine wheel lockup is to compare the rate of change of the wheel rotational speed. If the wheel is stopping turning "too quickly" then imminent lockup can be assumed and the system can react to the event. That is why there are multiple teeth on the wheel speed sensor reluctor wheel. The wheel RPM information is very accurate and can be determined on a tooth by tooth basis (by comparing tooth events to absolute time) so the system can instantly tell when the wheel speed starts to decrease too rapidly compared to the last wheel speed calculation.

Indeed the system likely also uses an accelerometer to compare decceleration of the chassis vs. wheel speed and the rate of wheel speed change to determine how much wheel slip to allow.

I doubt that buzzing and pulsation of the ABS system are an "intentional" engineering feature. Not sure about the Yamaha system but automotive systems have buzz and pedal pulsations based on the mechanics of the system and how the ABS is pulsating the brake pressure to each wheel. The feedback into the pedal is something that most engineers would love to eliminate completely. ABS systems also employ an electric pump to build system pressure into an accumulator and the "buzz" from the high powered pump operating at high pressure is difficult to completely isolate.

One of the criticisms of ABS systems in general is that they do not necessarily lead to less accidents based on accident statistics comparing ABS and non-ABS vehicles. Part of the reason is that the feedback from the ABS system (the buzzing and pedal pulsations) apparently "scare" or startle some drivers causing them to let off the brake pedal or panic further. The general rule is to isolate the ABS operation from the driver as much as possible to eliminate this, not deliberately cause the buzz and pulsations as deliberate feedback. Possibly in the FJR's case Yamaha did deliberately do this but I would personally doubt it.

 

[ionbeam]

I doubt that buzzing and pulsation of the ABS system are an "intentional" engineering feature

Intentional, per the FSM.

 

[wfooshee]

I doubt that buzzing and pulsation of the ABS system are an "intentional" engineering feature

Intentional, per the FSM.

[Cynic] Or "spin," because it's a consequence of the ABS function. [/cynic]

As for accident rates for ABS vs. non-ABS, I have seen the statement before that the ABS function startles drivers into actually releasing the brake (OMG! what's that??!!) and I find it plausible. I've asked friends who bragged about having ABS to find a dirt road and nail the brakes so they can feel what happens and be aware. A couple actually did and came away astonished. What's making all that noise? What's wrong with the system?

Second thing about ABS vs. non-ABS stats: I don't know anybody that counts accidents that didn't happen. ABS saved my bacon twice in my car. Did my non-accidents reduce my rate? Um, no. I do get a small discount on collision for having them, but I keep hearing about the discount being removed someday.

I've never ridden a bike so equipped, but I have my bike because its previous owner upgraded to an '07 to get ABS.

As for braking distance with ABS, again, ABS works by releasing the brakes. Of course it's going to give you a longer stop than you'd get with perfect application of non-ABS brakes.

 

[HYCLE]

I haven't read all of this but it seems interesting to me.

ABS info

 

[jestal]

I doubt that buzzing and pulsation of the ABS system are an "intentional" engineering feature

Intentional, per the FSM.

Yea, I think that is "spin" also as anyone I know that works on ABS systems wants to get rid of the feedback. Maybe Yamaha is just that good that their ABS could be transparent and they are the only ones that WANT the buzzing and pulsation.....NOT.

 

[jestal]

Second thing about ABS vs. non-ABS stats: I don't know anybody that counts accidents that didn't happen. ABS saved my bacon twice in my car. Did my non-accidents reduce my rate? Um, no. I do get a small discount on collision for having them, but I keep hearing about the discount being removed someday.

The stats just look at cars with ABS vs. cars without ABS and there is most often little to no difference in actual accident rates. If what you are describing were to be true then that would mean that ABS equipped cars enountered MORE accident situations than non-ABS cars and the ABS saved them part of the time for the statistics to equal out. Not likely. Maybe...but not likely. For each situation like yours where it "saved" you it seems to have "caused" an incident elsewhere.

I totally agree that most drivers need better eduction about ABS brakes. The feedback buzzing and pulsation of the pedal is certainly an issue with non-aggressive drivers that never experience lockup other than in an emergency. The simple idea to smash the brakes as hard and as fast as you can and HOLD them is counter-intuitive to generations of drivers taught to pump the brakes in an emergency to prevent skidding. I've found this much more prevalent in northern states where people drive on ice and snow and actually experience sliding quite often. Many of those folks REALLY need an education in ABS usage.

 

[Fred W]

Second thing about ABS vs. non-ABS stats: I don't know anybody that counts accidents that didn't happen. ABS saved my bacon twice in my car. Did my non-accidents reduce my rate? Um, no. I do get a small discount on collision for having them, but I keep hearing about the discount being removed someday.

The stats just look at cars with ABS vs. cars without ABS and there is most often little to no difference in actual accident rates. If what you are describing were to be true then that would mean that ABS equipped cars encountered MORE accident situations than non-ABS cars and the ABS saved them part of the time for the statistics to equal out. Not likely. Maybe...but not likely. For each situation like yours where it "saved" you it seems to have "caused" an incident elsewhere.

What you say above may actually be true to some extent. Once ABS came out drivers in the northern climes, where ice and snow abound, flocked to the added option, even though it significantly added to the cost of their new cars. It really does make a lot of difference in those slippery and varying traction conditions. So it may be that the group that chose ABS were subjected to more accident situations.

That said, I can also imagine that the people that had ABS equipped vehicles may become overconfident and put themselves in more accident situations.

Either way, in my opinion, anytime one has to rely on the limit of adhesion of their tires (or the use of ABS) to prevent an accident, you already screwed up big time.

 

[msfjed]

I just love 'scientific' discussions on motorcycle braking so for everyone that does too, check out this link. Does the weight of the bike really matter as the NHTSA study somewhat implies.

https://www.msf-usa.org/imsc/proceedings/a2...kingSystems.pdf

JED

 

[bluerocket]

Many good comments here, and I must agree that very few people out there can outride the capabilities of the FJR. I have had the opportunity to train with many good people and I have a suggestion...No matter what you ride, if it has two wheels take it out to an abandoned parking lot somewhere and practice 30, 40, 50, 60 mph decels. Take out the slack in the front brake, compress the front end and really grab a handful, bringing it to a smooth, solid stop (one foot down). Do not exceed your braking threshhold (point just prior to lock-up). Few practice this but it will save you one day. The brakes are engineered, the variable is the rider's committment to improve his skill.

 

[Dickf]

Just hadta post.

Agreed. Tires stop the bike providing the brakes have the ability to control the tire. The last bike I had that could not lock the front tire was an '82 Harley FX.

But...

There are other qualities. Without ABS (anti-skid to me), brake feel has a lot to do with how close you can approach the 80% rolling skid that approximated maximum braking.

But again...

If you have ABS, feel is not so important, because the rider can just honk down on the brakes and let the ABS take care of things.

Two types of vehicles can benefit greatly from anti-skid: motorcycles and high-performance aircraft. If you lock the front brake on a bike you end up on your head. If you lock up the brakes on an aircraft, you blow the ties and go for a wild ride, usually off the end of the runway.

I realize there are riders out there who can accomplish the 80% rolling skid in any situation, in any weather, with any road surface, with any tire. I am not one of them. If you are, you will not benefit from anti-skid.

**** Frederick

 

[MrWizard]

The MCN reports the FJR as taking 20-25 feet more from 65 mph than the Honda, Kawi or BMW.
From 120-125 up to 145 feet is a huge difference.

Anyone care to argue that this isn't REALLY important?

To me, it's almost a deal breaker.

Thanks.

A "deal breaker"? <_< You gotta be kidin' me! :blink:

Dude. Just hit the brakes 0.262238679 seconds sooner and you'll be stopped at the same spot as the Honda, Kawi or BMW.

and I'll bet you're just the guy that can do it.

You asked.