2008 Honda CBR1000RR - Light Makes Right

Central to the CBR1000RR's redesign is a five-pounds lighter, more compact engine with a 1mm-larger bore and correspondingly shorter stroke. To avoid spreading the individual cylinders farther apart, a separate cylinder block with Nikasil-coated cylinders is used in lieu of the old bike's cast-in cylinders with separate liners. The intake valves are larger (30.5mm vs 29mm) and now titanium, and shorter exhaust valves allow the camshaft to be lower in the cylinder hed for a 15mm-lower overall profile. The camshafts themselves use a new casting process that allows their walls to be thinner, saving more than one pound overall.

An all-new frame is made up of four main castings compared with the old bike's nine pieces, for a 5.5-pound weight savings and a 30mm-narrower profile. Lateral rigidity is up 13 percent, torsional rigidity increases by 40 percent and vertical rigidity is up by 30 percent.

The rear wheel is more than a half-pound lighter than the previous hoop, and the swingarm is 15mm longer. The engine appears to have been moved forward and up slightly, giving the swingarm more angle and allowing it to be longer without altering the wheelbase, which remains almost identical to the old model's.

The 1000's underengine exhaust has a servo-operated valve as well as a pressure-operated valve to route gases through its three chambers appropriately. The swingarm is arched for clearance, and the dual-exit muffler is much smaller than it appears in pictures.

The slipper clutch-the first on a CBR model-uses a ramp-style two-piece hub. A second set of ramps pulls the two pieces together under acceleration, adding pressure and allowing the use of lighter clutch springs (the design is similar to that used on the Suzuki Hayabusa). In turn, a cable can be used instead of the old bike's hydraulic actuation. The swap from hydraulics to a cable somewhat offsets the additional weight of the slipper clutch.

Nothing escaped Honda's weight-saving crusade on the 1000's front end: The wheel is a half-pound lighter, the rotors have fewer buttons (six compared with 10 each) and are drilled with four different sizes of holes, and the monobloc calipers have aluminum pistons instead of steel. The calipers (inset) are machined from the rear, plugged and welded, and their smaller size compared with conventional two-piece units allows the fork stance to be narrowed by 10mm, reducing aerodynamic drag and improving airflow to the radiator. Triple-clamp offset has been increased slightly to decrease trail by 4mm to 96mm.

The Honda's stubby front end features two ram-air intakes that are routed through the new frame and into the airbox. The aerodynamic design, including the short front end and minimalist rear end, is based on MotoGP research showing that a smaller side profile results in reduced drag in transitions, quickening steering. The turn signals are incorporated into the mirror to further improve aerodynamics.

Other weight savings come from a smaller battery, a shorter radiator, an aluminum sidestand and a lighter HESD unit that is also moved slightly rearward (and closer to the bike's center of mass). The shorter radiator can also be mounted higher, as the ram-air tubes are now routed through the frame spars instead of between the bottom triple clamp and radiator. The shorter radiator, mounted higher, allows more room for the exhaust header to snake forward before going under the engine, in turn freeing up space for the underengine boom box.