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Monday, September 27, 2010
For years, motorcycle riders have typically preferred to trust their own skill to electronic input at the controls, and so the usefulness of anti-lock and linked braking has been debated again and again. Although many riders have come to acknowledge the value of ABS in the touring and cruiser segments, the pulsating modulation and extra weight have seemingly been unwavering barriers to adoption for high performance sport bike riding.
So, when Takeo Fukui, the President and CEO of Honda, declared a few years ago that all Honda motorcycles above 250cc would have ABS brakes as an option by 2010, many in the sport bike segment were left wondering what might result.
Enter Honda's new Combined ABS system (C-ABS) braking system, now available on both the 2010 Honda CBR600RR and The 2010 Honda CBR1000RR sportbikes. Although the C-ABS adds close to 20 pounds, significantly, none of it is unsprung weight, enabling Honda to disguise the extra poundage within the central mass of the motorcycle. The relative simplicity also negates the need for the pressure control valves, parallel brake lines, or additional master cylinders that cluttered previous generations. This is not a reworked version of the linked ABS found on the Honda ST1300 or Interceptor, but a completely new, fully computerized system that is smarter, faster, and tuned specifically for aggressive sport riding.
Traditional ABS uses sensors and an electronic control module (ECM) to monitor for unusually rapid wheel deceleration-indicating that a wheel is about to lock and lose traction. The instant it is detected, the ECM closes the control valves, allows the fluid pressure to drop, and for a split second, caliper pressure is reduced. But within milliseconds, the ECM then reopens the valve and another attempt at stopping the wheel occurs. As this process repeats itself, the rider feels the familiar-yet-disconcerting pulsing at the braking controls that is so unnerving.
Honda's new C-ABS system is operated traditionally-until either brake is applied aggressively. Once a pre-determined fluid pressure point is reached, the C-ABS electronics take over completely, and both brakes become a fly-by-wire system that uses the rider's input only as a guide.
The ECM monitors wheel speed via sensors, and if either tire is about to skid, it precisely and smoothly modulates the hydraulic pressure to the calipers via high-speed servo-driven ball screws operating against tiny pistons. Simultaneously, fluid is also routed through a "stroke simulator" (a two-piece rubber-like cushion) that creates resistance and, therefore, feel at the controls. Although the Honda C-ABS is pumping in a similar way to a traditional system (albeit much faster), because the rider is insulated from the brakes by the stroke simulator, the job is completely transparent with no pulsing at the controls whatsoever.
However, the front and rear brakes on Honda's C-ABS are not merely linked-they are intelligently integrated together by the ECM. If the handlebar lever alone is squeezed hard, the ECU senses it, takes over, and simultaneously applies a degree of rear wheel braking before adding more stopping force at the front.
Because the rear braking occurs after the initial demand, but milliseconds before any additional front brake is applied, the rear suspension compresses in a controllable way. That minimizes front dive, stabilizes the chassis, and rapidly slows the bike in a settled, neutral attitude. It's as if you have suddenly become a flawless braker; no matter the situation, you are able to modulate both front and rear brakes to perfection.
Likewise, if the rear brake pedal is used alone (such as trail braking into a corner), the ECM does not engage the front brake until the rear wheel is near the point of lockup, and this allows a rider to use the rear brake much like a non-combined braking system.
While the C-ABS cannot be manually disabled, if the computer detects a problem, the fail-safe system simply defaults the machine to non-ABS brakes. A bit skeptical of a computer doing the thinking for me, I gassed up the Honda CBR1000RR and headed for a canyon road to experience the new C-ABS in real world conditions, outside of the friendly confines of the racetrack. Canyon roads are notorious for sand, gravel, and mossy water tracks flowing across them-a perfect test scenario.
Checking to ensure there were no vehicles behind me, I braked as quickly and as hard as I could-and the CBR executed a perfect, pulsation-free panic stop. Wow! Other than a slight numbness noticeable at the brake lever, the Honda had me convinced that I had been completely unassisted. Even when literally stamping on the brake pedal as hard as I could-at speed-the result was serious slowing without either wheel locking up or pulsing against my foot.
And so it went on-regardless of the traction-losing obstacles I threw at it, the stellar braking and handling performance was repeated over and again. As technology continues to advance our sport at the highest levels, we can either choose to embrace it or ignore it. Not only does Honda's C-ABS result in a much safer road riding experience, but it also allows for a much more confidence-inspiring ride in the real world. The debate may continue to rage on, but the revolutionary braking system on the Honda CBR1000RR C-ABS has made me a believer.
Source: http://www.ultimatemotorcycling.com
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BIKES TECHNOLOGY
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