Since its original 1992 introduction, Honda’s iconic Fireblade has evolved into an incredible 1000cc sports motorcycle. It’s also been the base of a competitive race machine, on short circuits around the world and the roads of the Isle of Man TT.
Time and competition – marches on and for 2020, Honda is drawing a line under where the CBR1000RR Fireblade has been and looks forward to where it’s going.
The brand-new CBR1000RR-R SP Fireblade – has been created, with heavy involvement from Honda Racing Corporation, to carry the legend forward.
Leaning heavily on the engine and chassis technology of the RC213V-S ‘street-legal MotoGP machine’. with aerodynamics drawn from the RC213V MotoGP bike, the new Fireblade have been designed from the ground up – in terms of engine, handling and aerodynamics – for outright track performance.
The CBR1000RR-R Fireblade SP’s 1000cc inline four-cylinder engine is completely new and designed with heavy input from the HRC MotoGP development program.
To achieve the required valve size, combustion efficiency and friction reduction to generate these numbers, the RR-R engine shares the same ‘over square’ 81mm bore and 48.5mm stroke as the RC213V – a radical change from the 76 × 55.1mm of the previous design, and the largest bore size among inline four-cylinder 1000cc machines.
The valve train is driven by a new (patent pending) semi-cam gear train system. To drive such high-rpm/high-cam lift performance the chain is driven from the timing gear located on the crank shaft via the cam idle gear – this makes it shorter in length.
Forged, lightweight TI-64A Titanium (a material developed by Honda) con-rods and con-rod caps save 50% in weight compared to Chromium Molybdenum steel versions; they also employ HB 149 Chromium Molybdenum Vanadium (Cr-Mo-V, again a Honda development) steel bolts and do without fastening nuts.
To ensure durability the same configuration as the RC213V-S is applied to the sliding surfaces – the small-end bushings are made of shaved C1720-HT Beryllium copper (because of its high-rpm reliability) while the surfaces of the big-ends are treated with DLC.
The reduction in physical size of the CBR1000RR-R SP’s engine opened up new packaging options around it for the new frame and swingarm – with completely revised geometry. The goals? Even more accurate high-speed steering, improved stability under acceleration and braking, and feel for front and rear grip on the limit. And at the very highest level of competition.
The diamond frame is constructed from 2mm aluminium and allows much more accurate tuning of the rigidity balance; in manufacture, after the four main frame components are welded, the engine now mounts in six locations improving machine handling. Vertical and torsional rigidity are increased by 18% and 9%, with horizontal rigidity decreased by 11% – all aimed at producing maximum levels of feel.
Wheelbase is now 1,455mm, with rake and trail of 24°/102mm (from 1405mm, 23°/96mm) for stability. Wet weight is 201kg. There have also been considerable changes to balance and centre of gravity; the crankshaft is 33mm further from the front wheel spindle and raised 16mm. This evens out weight distribution, while the higher c-of-g reduces pitching and improves side-to-side agility.
The swingarm – stamped out from 18 individual thicknesses of aluminium and as used by the RC213V-S – is 30.5mm longer, at 622.7mm, but weighs exactly the same as the previous design. Its horizontal rigidity is reduced by 15%, with vertical rigidity maintained to generate grip and feel.
Alongside its new engine and chassis the CBR1000RR-R SP has an aggressive new fairing design. It’s no mere styling exercise however; the drivers in development were to create a class-leading drag coefficient (with a tucked-in rider under track conditions) and restrict lift under acceleration while improving braking stability.
The first part of the process was to lower the fuel tank cover by 45mm (compared to the previous design) decreasing the frontal area with the rider prone. At a 35° angle the screen smoothly channels airflow from the upper fairing over the rider and seat cowl, which itself presents the minimum possible drag resistance. The left and right upper fairing slits reduce yaw and roll resistance while turning.
To make steering easier a convex surface on each side of the front mudguard moves air flow away from the front wheel, smoothly directing it to the fairing sides. Cooling air for radiator and oil cooler has been optimised by aerodynamic management of both velocity and pressure of air flowing from the tyre.
The lower fairing has been extended close to the rear tyre, and shaped to channel air downward. This has two effects: in dry conditions, less air hits the tyre, lowering drag; in the wet, less water hits the tyre, improving grip. To let air flow around the rider’s feet with minimum resistance the sides of the rear hugger are carefully shaped while its upper side is cut-out to vent air that channels up from underneath either side of the swingarm, decreasing rear lift.
The net result of all this work, with the CBR1000RR-R in stock race trim, is a best-in-class drag coefficient value of 0.270.