Development Story: New-Generation Honda CBR/CB500s
8/7/2013 5:18:00 PM
There's a whole new generation of young riders looking to enter the sport of motorcycling on bikes that are fun to ride, nimble and easy to handle, affordable and economical to operate, plus distinctive in appearance. For this set of buyers, Honda has hit a grand slam by creating a trio of modern-era 500cc machines that redefine the middleweight category. These three bikes take aim at three popular styles of bikes that resonate with their own identity, yet all are filled with Honda quality and value, through and through.
First, there's the CBR500R, a lightweight and nimble middleweight sport bike that's just right for riders moving up in displacement categories, as well as for experienced riders who just love riding a great-handling bike. Next, there's the CB500F naked sport bike, a great choice for independent-minded riders in search of a mid-sized entry-level bike with extra attitude, but one that's also a great daily ride. And there's also a middleweight adventure-style bike, the CB500X, a bike that follows the lead of the popular NC700X introduced in 2012. For riders who want to add a smaller, lighter and eminently affordable adventure-style bike to their lives, the CB500X is just the ticket.
Each of these brand-new models has its own look and personality plus a tie-in to larger bikes in the Honda lineup, and they also share that distinctive, high-quality Honda feel. Despite their unique appearances, these three bikes share the same basic chassis components and enginea smart move, since sharing common elements helps reduce development and production costs, resulting in a markedly lower consumer price point.
As its name suggests, the CBR500R features full bodywork much like that found on the potent CBR600RR and CBR1000RR Honda sportbikes. Sportbike riders, whether well established in the sport or still developing their motorcycling skills, always prize the excellent handling traits that come with a light and responsive mount. And the new, lightweight and nimble CBR500R absolutely delivers in that departmentthere's plenty of well-rounded performance on tap here. It's just the right size for sport riders moving up from the entry-level Honda CBR250R, but even experienced sportbike riders will appreciate the handling characteristics of this 425-pound bike. Its aerodynamic bodywork provides significant advantages in air management for added rider comfort, along with a low drag coefficient and effective engine cooling, rounding out a package that looks as good as it works.
Naked sport bikes form another distinct category of motorcycling, one that fosters the image of independence and non-conformity. And that's especially true with the CB500F, a bike that looks like a first-cousin to the liter-sized CB1000R. This modern and sporty 500cc naked bike not only carries a full load of attitude and style, it also delivers plenty of performance and versatility. Tipping the scales at only 420 pounds, it's got everything you need, and nothing that you don't. Whether it's used as a daily commuter machine, an affordable weekend ride for backroad day trips, or a bike for hanging out at the local gathering spot, the CB500F serves as a great option for just about any kind of street use. Its comfortable, neutral riding position and slim profile let riders feel right at home in the saddle. For a bike that's affordable, stylish and fun, it's tough to top the new CB500F.
We all understand that half the fun of motorcycling is the mental escape it provides when you're tied down at the 9 to 5 job. For riders who love to dream about getting far away on a ride, the middleweight CB500X is a fantastic option that follows in the tire prints of the recently introduced and highly acclaimed NC700X adventure-style bike. This is a bike that begs to travel new roads and discover new sights, a fun-to-ride motorcycle with an extra dose of versatility. The compact windscreen can be adjusted in height, and it also has a comfortable adventure-bike seating position, plus a larger-capacity fuel tank that has been carefully shaped to allow the rider unrestricted movement. It features a longer-stroke 41mm front fork that produces 4.9 inches of travel, and a wider handlebar allows for easy steering inputs. And while this the CB500X works well for longer-range adventure tours, it also serves as a versatile ride to fulfill those everyday needs too. For riders seeking a little more adventure in their lives, the CB500X delivers on that idea at a very affordable price.
Regardless of market placement, all three bikes share an all-new engine and Honda's engineers decided that a sleek parallel twin would serve best to generate sufficient torque in the low-rpm range to produce the kind of fun, easily accessible powerband that is a hallmark of all three bikes. And so this series of bikes became 500cc liquid-cooled parallel twins with a bore and stroke configuration of 67 x 66.8mm. The stroke of 66.8mm was the maximum possible, given the compact engine dimensions the engineers had also set as a priority. The 7mm bore interval in this engine is the same as the bore intervals in the CBR600RR; this tight distance results in a compactand light weightengine.
The valvetrain incorporates four valves per cylinder actuated by dual overhead camshafts. The intake valves measure 26mm in diameter, the exhaust valves 21.5mm, and narrow valve stems help reduce reciprocating weight and engine friction. This DOHC configuration was chosen for higher performance; it gave the engineering team greater latitude in developing the shape of the combustion chamber, the shape of the ports and the layout angle of the valves, while also allowing the use of lighter valves. Careful attention was paid in particular to creating a markedly straight-line flow from the air cleaner through the intake ports and out the exhaust pipe to maximize efficiency.
The cylinder head design also incorporates a roller rocker arm for a more compact layout along with reduced friction. The choice of a shim-type valve adjustment system allowed incorporation of a lighter rocker arm setup that, in turn, allowed for a lower valve-spring load to further reduce power losses through engine friction. The cams are driven by a silent-type cam chain for reduced engine friction, and the surfaces of the cam-chain pins are treated with vanadium for lower friction and increased toughness. Compression ratio is set at 10.7:1, and to reduce piston noise and friction at the relatively high top engine speeds slated for these bikes (redline is 8600 rpm and rev-cut occurs at 9100 rpm), the short 67mm piston features asymmetrical skirts that are the same length but differ in width. Using technology applied to the CBR600RR, striations on the piston skirts aid oil retention for better lubrication, and the piston pins and connecting rods are also treated with a friction-reducing special protective coating. The 180-degree crankpin design and an engine counterbalancer help smooth operation, and preloaded scissor gears are used for the primary and balancer gears to reduce gear whine/engine noise. All in all, a sophisticated package.
A six-speed gearbox complements the power output of this engine, and the triangulated layout between crankshaft, mainshaft and countershaft is very similar to that of the four-cylinder CBR-RR engines, which aids in creating a very compact unit. Engine weight, at 116 pounds, is laudably light. In addition, the gear-change mechanism uses the same gearshift structure and gearshift link design used in the ultra-high-performance CBR600RR and CBR1000RR sport bikes to yield high-quality shifting action and feel.
Honda's Programmed Fuel Injection (PGM-FI) system delivers the appropriate fuel mixture according to existing riding and atmospheric conditions for crisp throttle response. A pair of 34mm throttle bodies feed the engine, with the injectors located within the throttle-body assembly. All of this technology helps give all three 500s an especially responsive, revvy nature and a high-quality feel.
The engine hangs as a stressed frame member housed in a monocoque frame evocative of Honda's MotoGP racing machines. The cylinder head features four solid attachment points for engine hangers, which allows the rigidity of the engine to add to chassis rigidity. Such a design lends itself to a more simplified frame shape, yielding a more lightweight and compact chassis. The resulting frame is a diamond-shaped unit with a 35mm steel tube main member, and the final design is significantly lighter than other comparable designs, which adds greatly to the handling prowess of all three bikes.
The CBR500R and CB500F share the same wheelbase of 55.5 inches, while the CB500X spans 55.9 inches between axles. The X model also has one degree more steering rake than its two siblings (26° 5' versus 25° 5'), and its 41mm fork yields 4.9 inches of travel in contrast to the 4.3 inches of fork travel with the other two bikes. All three share the same Pro-Link® single-shock rear suspension system, which offers nine-step cam-style spring preload adjustability and 4.7 inches of travel. Thanks in part to this slightly taller suspension setup the CB500X seat is slightly taller at 31.9 inches, versus 30.9 inches for the CBR500R and CB500F. Even so, the CB500X seat is perched nearly an inch lower than that of the larger NC700X adventure-style bike, which makes it distinctly more friendly feeling for riders with shorter inseams.
All three models share the same lightweight cast aluminum wheels, a 120/70-17 front and 160/60-17 rear. These wheels follow the designs used for the latest CBR600RR and CBR1000RR wheels. The brake setups are likewise identical among all three 500s: a twin-piston caliper and 320mm wave-style disc up front, and a 240mm wave disc in back. The front brake in particular offers excellent stopping power and feel. The wave design reduces unsprung weight and it also offers excellent heat-dissipating qualities. ABS is an option with all three bikes and the ABS systems are independent, not linked, between the rear and front brakes.
So there you have it: three different bikes, three different riding experiences for three different kinds of riders. But all three bikes are lightweight, nimble and fun to ride, and each one possesses a level of quality and sophistication that makes it a fantastic value for the money.