It’s becoming more and more likely that all sportbikes in the very near future will have ABS as standard equipment. If you buy a BMW next year, it will have ABS — the company announced recently that the safety feature will appear on its entire lineup beginning in 2012. Governments in both Europe and the USA are pushing for mandatory ABS on motorcycles, citing fewer accidents and improved safety. Until recently, this was a definite cause for concern with sportbike riders, as systems for motorcycles were quite obtrusive, adding weight and complexity in addition to underperforming — intervening when they shouldn’t, and not working when you think they should.

That has all changed in the last couple of years with the introduction of various systems specifically designed to work on sportbikes, offering light weight, higher thresholds of operation and smooth activation. Here we have three literbikes with such systems: The BMW S 1000 RR, with the company’s Race ABS that is offered in conjunction with its Dynamic Traction Control system; the Honda CBR1000RR ABS with its combined electronic setup that is a brake-by-wire system and links the front and rear brakes; and the Kawasaki ZX-10R ABS with KIBS — Kawasaki Intelligent anti-lock Brake System.

We are well familiar with the BMW S 1000 RR’s ABS, as every test unit we have sampled to date has been equipped with that option. The BMW, equipped with ABS, has won our literbike shootout two years running, an indication of how well the system works — although we still disable it for racetrack use. We likewise have plenty of experience with the current generation CBR1000RR, which has consistently ranked near the top of our literbike comparison tests since its introduction in 2008. And while we haven’t sampled an ABS version before, we have tested the CBR600RR C-ABS model (“Future Indicator”, May ‘09) with favorable results. The current ZX-10R we have also tested numerous times this year, although we’ve had limited experience with KIBS, (we had the KIBS-equipped ZX-10R for a week and wrote about it in our last literbike test) which is an advancement of the company’s K-ACT (Kawasaki Advanced Coactive-braking Technology), which we have used extensively on the Concours model. See the attached “ABS Tech” sidebar for more information about each bike’s system, and for even more information about each bike, visit www.sportrider.com/magazine/1112.

Give it a Brake
To get an idea of the outright braking capabilities of the three bikes, we headed to Auto Club Speedway’s dragstrip facility and scared Kent into making some panic stops with our data acquisition strapped aboard. The results of those tests are shown in the attached sidebar. We know from past experience, however, that the major benefit of ABS is not in absolute stopping distance — an experienced rider, given some practice attempts and ideal conditions, can stop in a shorter distance than most systems. So, we sent Kent, Bradley and Eric Nugent on a street ride with instructions to find some wet, dirty and gravelly roads and experiment with each bike’s ABS to see how they reacted to various scenarios in not-ideal conditions — the real value of ABS.

In stark contrast to the BMW, the CBR1000RR provided the smoothest stops with the most control. “Under aggressive braking in water, gravel or whatever I could find, even a full-blown dirt road, I was not able to lock up the brakes,” commented Eric. “There is no trace in the lever that you’re activating the ABS like you have with the BMW and the Kawasaki.” And that may in fact be an issue with the Honda’s system: With no feedback you simply don’t know if you are applying enough lever pressure for the required conditions, and all our riders expressed concern that they were not stopping as quickly as with the other bikes — something that the data in some respects confirms. “During both wet and dry stops, the bike comes to a complete stop without lifting the rear and without so much as letting the rear squirm around,” wrote Bradley in his evaluation. “The bike just stays perfectly in-line. The one thing about the Honda is that the feel at the lever is a little numb, meaning you don’t get much feedback. You really have to trust the system, and know that ample pressure is being applied to come to a stop.”

The Kawasaki perhaps combines the best of both systems, with the shortest stopping distances in the test, all with little drama and only slight cycling felt in the lever or suspension. Kent: “While it doesn’t have the highest activation threshold, it provides enough pressure feedback through the lever that you don’t feel like all control has been taken away from you. In a dry-pavement panic stop, it would just get on the edge of letting the rear tire start to get out of control, but not any farther, and certainly nothing like the BMW. In the wet, it was nearly as smooth as the Honda, while seemingly providing more stopping power.”

Certainly the BMW’s system is the most track-oriented (and is labeled as such) with its higher thresholds of operation. “And you can turn it off, something you can’t do with the other two,” noted Kent. The Honda’s system is decidedly more safety-oriented than the other two, and would definitely hinder lap times on the track. The Kawasaki again provides the best compromise of street safety and performance, but we do have some contradiction from the company: Even though the ZX-10R’s literature talks about track riding, representatives — quick to point out that KIBS is a safety feature first — were reluctant to allow us to test the bike on-track.

And Everything Else?
Turning to other aspects of each bike’s performance, this street-only test enforced much of what we already know. The BMW is characterized by its incredible engine and stiff chassis, and is clearly the most knife-edged of the trio. That makes it both fun and intimidating to ride, and the riding modes, traction control and ABS are almost mandatory to harness its power. The ZX-10R came up a bit short in our literbike comparison test earlier this year. Just as in that test, two of our three testers favored the Kawasaki over the BMW but the scores still favor the BMW. The ZX-10R’s ergos are a bit less comfortable for street use, and its slightly abrupt throttle was even more noticeable in this test as our BMW test unit was smoother than units we’ve sampled in the past. Unfortunately, the Honda — the oldest platform of the group — now lacks the refinement of the Kawasaki and BMW (in aspects other than its ABS, of course). Its stomping midrange now only highlights a lack of top- and bottom-end power, and with 25 pounds of ABS it’s the heaviest bike in the test; its softly sprung chassis is certainly ready for an update. “The Honda just seems to take a bit more work to keep up with the others,” Eric noted in summary.

And where does that leave us? The Kawasaki combines short stopping distances and excellent control for both performance and safety, and has the best ABS of the three bikes tested here. The BMW is still the better overall package according to the scores and subjective comments, but that is in spite of its ABS, not because of it. Perhaps more important is how little the current ABS offerings affect the overall performance of these literbikes. Bradley concludes it best: “Unless my intention was to use the bike solely for racing, I would buy any of the three bikes with ABS rather than the standard model. I have a newfound respect for ABS; it’s not that I would take advantage of it often, but I am now noticing more and more scenarios where it would be advantageous.” sr

ABS Tech

Anti-lock braking systems have been offered for many years on various touring and sport-touring motorcycles, but only recently has ABS been available on sportbikes. Previous systems have had limited performance on twisty roads or the racetrack, in addition to adding a significant weight penalty. The three systems tested here, however, have performance and safety benefits applicable to a sportbike, with two of the systems adding a minimal weight penalty. A basic system consists of wheel speed sensors to measure individual wheel speeds, hydraulic pumps to control braking pressure at each wheel, and an ECU to manage the system. When the system detects a wheel slowing too quickly, or one wheel slowing significantly more than the other, hydraulic pressure to that wheel’s brake is reduced, allowing the wheel to return to an appropriate speed.

Both the BMW S 1000 RR and Kawasaki ZX-10R use versions of the Bosch Generation 9 motorcycle-specific ABS, which combines the pump and control unit in a single, lightweight unit. The system’s Plus variant, as used in the ZX-10R’s KIBS, uses an additional pressure sensor within the unit, which, according to Bosch, “takes effect even when pressure is being built up during emergency braking. This specifically prevents the rear wheel rising.” As opposed to the version used on Kawasaki’s Concours that works only when the bike is close to vertical, KIBS operates even when the bike is leaning. The system monitors wheel speed, caliper pressure, engine rpm, throttle position, clutch actuation and gear position. This information is provided to the KIBS ECU every five milliseconds, a significantly higher sampling rate than the Concours’ setup, and the engine data gives the system increased brake control during downshifts. According to Kawasaki, KIBS is capable of predicting slip and modulating brake pressure as opposed to a simple on/off operation, making it suitable for sportbike use. On the ZX-10R, KIBS adds seven pounds of weight.

The S 1000 RR utilizes the Enhanced version of the Bosch Generation 9 ABS, which adds integrated braking. On the BMW, the front brake lever works both front and rear brakes, while the rear brake pedal works only the rear brake. Additionally, a “very elaborate rear-wheel lift-off detector” is capable of discerning the difference between a bump in the road and rear-wheel lockup. The Race ABS setup is combined with the bike’s traction control, and changes its operation in the various riding modes. In Rain and Sport modes, the ABS “intervenes early enough to prevent the wheels from locking and the rear wheel from lifting off the ground.” In Race mode, ABS intervenes later but still prevents the wheels from locking; the rear-wheel lift detection is deactivated and the rear wheel is allowed to come off the ground. Slick mode is identical to Race, but ABS on the rear wheel is deactivated, allowing the wheel to lock when the foot pedal is depressed and the rider to skid into a corner. While we haven’t tested a non-ABS S 1000 RR to date, BMW claims the Race ABS system adds 5.5 pounds to the bike.

Honda’s Combined ABS is a patented system designed for sportbike use that is more electronic braking than simply ABS. The system’s objective, according to Honda, is to combine the front and rear brakes to reduce the stopping distances that result from using more of one than the other. As such, the front lever works both brakes, as does the rear pedal; however, the rear brake pedal only works the front brake when rear wheel lockup is sensed. This allows an experienced rider to use the rear brake as normal for sport riding. The C-ABS utilizes two hydraulic sensors; activating either brake generates pressure in the sensors, and the system’s ECU calculates how much braking force to apply using a hydraulic pump for each wheel. The elaborate system allows some advantages compared with conventional ABS. According to Honda, more control over the application and release of the brakes controls pitching of the motorcycle, while the isolation of braking inputs from caliper pressure reduces pulsing at the brake lever. A failsafe function returns control to normal operation in the event of a problem — but the system adds 25 pounds to the CBR’s weight according to our scales.

Data Analysis

In order to fully test the braking systems on each bike, we used our Racepak G2X data acquisition system to record a series of stops with Kento at the controls, and looked at stopping distances as well as braking deceleration (in G) for each stop. In addition to pointing out performance differences between the three bikes, it’s also worthwhile pointing out some details about braking in general that is shown in the data.

Note that the stopping data is shown here relative to distance, and the speed traces drop sharply as speed approaches zero. Here you can see an important aspect: Even at maximum braking, it takes exponentially more distance to slow from a higher speed than a lower speed. This is why it is critical in any sudden stop to get to maximum braking as quickly as possible. Note also that it takes a certain amount of time (and distance) to get to maximum deceleration, as shown in the braking G plots. This is a function partly of the rider’s ability to get to maximum braking, but also how quickly weight is transferred to the front wheel without it going into a skid. ABS can help somewhat in this aspect, but the rider’s skill also plays a big part. Again, this shows how important it is to master all aspects of braking, both for quick lap times on the track and safety on the street.

Because of the friction relationship between a tire and the road surface, the maximum deceleration typically generated on clean, dry pavement is approximately 1 G. Another limiting factor, however, is the motorcycle’s rear wheel lifting off the ground. Due to the relationship between a typical sportbike’s wheelbase and the position of its center of gravity, this also occurs at about 1 G of deceleration. By fitting each bike with identical tires (see sidebar) we eliminated one variable in the equation, but each bike’s weight distribution does affect its braking performance. In addition, the rider can improve that weight distribution by sitting further rearward on the seat and not raising his torso excessively.

For each bike, we had Kent perform three sets of three stops: one stop with the rear brake only, one with the front brake only and one with both; that sequence was repeated three times. The best stops using rear-only, front-only and both brakes are shown here displayed as speed over distance and braking force over distance. Because it’s practically impossible to begin each test from an identical speed, we lined all the data up at 60 mph and calculated stopping distance from that point, as is typical in the industry. Note that the deceleration diagrams (Braking G) begin ramping up at different points, not because of any performance discrepancy, but because the starting speed of each test is slightly different.

To account for the BMW’s changing ABS in the different riding modes, we ran the test in both Sport and Slick modes. Sport mode offers ABS on both wheels and limits the rear wheel from coming off the ground, while Slick mode deactivates the rear-wheel lift feature as well as deactivates ABS on the rear wheel when the rear brake pedal is used.

The BMW, in both modes, takes slightly further to get to maximum braking G but also holds a consistent value over the course of the stop. The Honda takes the furthest distance to ramp up to serious braking G. Again, however, there is a noticeable step where the system activates the rear brake and adds to the stopping power, with braking G rising from an early plateau of approximately .8 G to .94 G, almost matching the Kawasaki later in the stop.

The BMW in Sport mode takes a bit further to get to maximum braking G, but again holds a fairly consistent value of approximately .9 G until stopped. While the stopping distances in Sport mode were the same using the front brake only or both brakes, Kent reported that the bike was slightly more controllable when he applied both brakes. In Slick mode, the BMW stopped slightly better using both brakes, although Kent stated that the rear brake was practically useless as the rear wheel was in the air during most of the stops. And, even though the S 1000 RR stopped better in Slick mode than in Sport mode, it was getting significantly more out of shape in Sport mode — opposite to what you would expect. With the BMW, using both brakes in Slick mode provided the shortest stopping distance and the most control.

The Honda, compared with the other bikes, simply doesn’t provide enough stopping power early in the test — at higher speed, where it has the most effect — to stop as quickly. Braking G is more consistent over the course of the stop than it was in the front- and rear-only stops, without the jump as the system applies the brake not being used. But at the same time, braking G never goes above the peak value seen during the front-only stop and stopping distance is actually further using both brakes. Notably, the Honda’s two other front-only stops (not shown here) were significantly longer than any of its both-brakes stops, and in general stopping performance is better with both brakes in spite of the anomaly we found here. One theory is that the Honda’s system, lacking feedback and being ultra-smooth at the lever with no pulsing, can lull its rider into not braking as hard as possible in a panic stop.

Specifications

BMW S 1000 RR

MSRP

Engine

Chassis

Honda CBR1000RR ABS

MSRP

Engine

Chassis

Kawasaki ZX-10R ABS

MSRP

Engine

Chassis

Opinions

Getting the call to ride the BMW S 1000RR, CBR1000RR and ZX-10R to most would be like a dream come true! (Well, it is…) But when the three little letters ABS come into the conversation, it becomes another story. “Hey, do you want to take our beautiful bikes and go slam the brakes on as hard as you can in some water, gravel and maybe some dirt?” I’m like, “Uh...Sure, will you still make me Chocolate Chip Cookies if something goes wrong?” First stop: A flooded road. I was surprised at just how hard you can brake in the wet, a lot harder than I would feel comfortable with a standard braking system. The BMW seemed to have the most power in the wet. Second stop: Loose gravel. While both the BMW and Kawasaki feel similar in that you can feel the system working through the levers, using the rear only makes quite a bit of ruckus in the rear ends, like your sprocket bolts just sheared off, whereas the Honda is as smooth and quiet as can be but didn’t feel as powerful as the other two. Third stop: Dry road. The BMW in Sport or Race mode was quite a handful in the dry under extreme braking, with the ZX-10 being pretty solid. The Honda, again the smoothest but not the quickest to stop. Of the three, I think the ZX-10R as the best all-around ABS system for the street. And this little piggy got all three bikes back without a scratch! Just sayin…

If your boss asks you to jump, you say “how high?” But when Kent first asked me to ride directly towards the generously sized water puddle we found on our street ride and grab the BMW S 1000 RR’s brakes with absolute force, I’ll admit I was hesitant. Nevertheless, I crossed into the wet patch at an indicated 45 mph and grabbed the brakes as hard as I could, half expecting things to go sour. They didn’t of course, and so I mounted the Honda and Kawasaki and did as many passes as possible. I was surprised to see how different all three systems acted too. In the dry especially, the BMW’s system allowed the bike to get out of control, which required I modulate the brakes — a sign that the system was developed with racetrack use in mind. The Honda has the most opposite feel, and the bike comes to an absolutely controlled stop with ease. The numb feel at the lever is a concern for me though, and it doesn’t feel like as much braking force is applied. I feel like the Kawasaki perfectly combines the positive characteristics of each of the other systems. The ZX-10R’s ABS allows the front tire to slip just slightly before traction is regained, which gives you the feeling of still being slightly in control of the bike. Plus there is still enough power to come to a quick stop. By day’s end, I had a new respect for ABS; each of these systems is truly brilliant.

Picking between these bikes is a lot different than if the Kawasaki and Honda were standard models. A lot of this depends on your intended usage. If I was going to be doing a lot of track days, I’d probably go for the BMW, simply because you can turn off the Race ABS. However, if I was riding primarily on the street with only the very occasional track day, then I’d probably opt for the Kawasaki. The KIBS really impressed me with its ability to stop extremely hard in all kinds of conditions while allowing me some feedback instead of simply taking over completely and leaving me with a mushy brake lever.

The Honda’s C-ABS is incredibly smooth but it’s a little too numb for my tastes during very aggressive braking or a panic stop. And while the S 1000 RR’s Race ABS works great on the track for the most part, I didn’t care for how the rear end would get out of shape in the higher system modes during a panic stop on the street. That added issue could be the difference between avoiding something or ending up on the ground in an emergency.

And lastly, I still see a lot of street riders poo-pooing ABS because they think they’re skilled enough not to need it. Trust me, you will not be able to panic stop as quickly as these systems on a cold rainy day with wet brake pads and cold tires — period.

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Bridgestone BT-016 Pro

To ensure that braking performance with our three ABS bikes was not dependent on a tire advantage, we fit all three bikes with Bridgestone’s new BT-016 Pro. An evolution of the company’s excellent BT-016, the Pro uses new rubber compounds to improve mileage and wet-weather performance. While the standard BT-016 uses the company’s Three Layer Compound in the front and Five Layer Compound in the rear, both front and rear Pros use the 3LC. The company claims increased cornering and stability in dry conditions, but the real improvement is said to be in wet conditions, with all aspects of performance improved. True to that claim, our testers were able to stop hard enough in wet conditions to raise the BMW’s rear wheel off the ground.

The Bridgestones performed with consistently high levels of grip for the stopping tests at the dragstrip. The tires also provided excellent grip on the street portion of the test, with “great feel mid-corner,” according to Bradley. Additionally, the tires help with quicker turn-in on each of the bikes compared with the OEM rubber. The BT-016 Pro is available in one front size (120/70) and three rear sizes (180/55, 190/50 and 190/55), with retail pricing identical to the BT-016. For more information visit www.motorcycle-karttires.com.