Evolution of the CRF450 RALLY for the 2017 Dakar Rally
Honda had once won the Paris Dakar Rally, to most grueling rally in the world, four consecutive times. After a hiatus of 24 years, Honda return in 2013. Through many experiences and occurrences, the modern Dakar Rally has developed into what it is today. The race overs nearly 9,000 km, is raced over 4,000 km, and spans a fortnight. The real victory of the Dakar lies in not only riding faster than the competition, but overcoming the harsh environments and unpredictable problems.
The CRF450 RALLY factory machine has evolved, and enters its fifth year. How well has it evolved?
Acting Large Project Leader, Monster Energy Honda Team Rally Project
Project Leader, CRF450 RALLY design
Involved in development since Honda returned to the Dakar Rally in 2013. A true adventurer, taking leave in 2013 to ride local buses to follow the rally.
CRF450 RALLY Finished Vehicle Tester
Involved in development since Honda returned to the Dakar Rally in 2013. Involved in supporting the Honda South America teams racing CRF450 RALLYs. Well acquainted with the region.
CRF450 RALLY Engine Tester
Joined the rally team in 2016 to develop the 2017 CRF450 RALLY. A specialist in off-road engines, formerly involved in ATV and UTV development.
Involved in development since 2013, an engineer that has seen firsthand how rally bike suspension has evolved. Honing technologies at the frontline, with a view to applying these technologies to production models.
What is the theme for the 2017 model compared to the 2016 model?
Noda “Strong. And fast.” The riders were satisfied with the 2016 model’s competitiveness, so we kept what they liked, and focused on reliability for the 2017 model. The bike had to build trust with the rider, and with the team. The 2017 CRF450 RALLY is still as fast, with all of the accumulated experiences, but is also stronger.
How has the engine been updated?
Takahashi In 2013 we developed a DOHC rally engine, and the next time will be our fifth. The riders are impressed with the engine’s performance such as power. In 2016, we had some unforeseen issues during the rally, so we have developed the 2017 engine making sure that we haven’t missed even the smallest detail, and made sure it is a mature, reliable engine. We gained confidence with Joan racing consistently and winning the long and rough China Grand Rally. We raced our latest version for 2017 at the Morocco Rally, Paulo had some problems with it, so we did the analysis, improved the engine, and will be racing the Dakar with updated engines.
Sasaki From the telemetry data, Joan uses the torque band well to gain speed. Engine durability suffers more if the rider uses the rev range with high torque fluctuations, rather than revving at peak power for extended periods. The 2017 engine was designed to comfortably deal with this issue. The engine was also designed to recover rapidly from unforeseen occurrences.
How has the suspension been updated?
Tomura Rallies consist of all sorts of surfaces. Liaison stages are on paved roads. Special stages vary from large and hard dirt which isn’t bad for grip, but hard on the bike at high speeds, to rocky tracks, terrain with rocks and sand, and hard-to-handle dunes. And all of these surfaces in one day. We aimed to mature the suspension for 2017. We weren’t unhappy with the 2016 suspension, but we changed the rear suspension’s link ratio and increased stroke. The change in the Prolink link ratio reduces the rider’s feeling of sitting high off the ground. This feeling depends on the seat height and the distance between the seat and steps, but these are static. We worked closely with chassis design to reduce this "too high" feeling when the bike was in motion.
Sasaki Chassis design also worked on identifying this "too high" feeling. During testing, we first worked on the static height, by lowering the seat. The rider would test the bike with less sponge in the seat from the rider’s position to the rear fender. Paulo, who is not tall, wanted the seat lower, but that alone was not the cause.
Noda The seat height can only be reduced by so much. When there is a large input on the suspension, the rear wheel rises towards the rear fender. Seats that are too thin are not comfortable for the long liaisons on paved roads, leading to fatigue. We had to maintain comfort while reducing the "too high" feeling. The suspension team looked at the link ratio, chassis design changed the rear sub-frame rigidity and positioned the rear tank lower.
Sasaki We changed how the CRF450 RALLY’s carbon fiber sub-frame is made, reducing vertical rigidity, so the sub-frame itself was more flexible, giving the rider a softer impression during riding. The rear tire’s stroke limits how low we can position the seat. We listened to the riders, and in the end, the suspension and chassis teams worked together to improve the bike.
Were there any other new endeavors with the suspension?
Tomura The development team applied a new technology called “Challenge Ball.” We have had it since 2016, on Kevin’s machine. It’s effect is better times. We’re trying out suspension that is fast, safe, and optimal on any surface. We’re listening to the riders, and developing the technology on the track, as we consider rallies a “lab on wheels,” to expand its application to production models.
What were the difficulties with applying the “Challenge Ball?”
Tomura Rally bikes are designed as a complete package, so if you want to try a new component, various teams have to change various layouts, which causes problems. We proceeded with the cooperation of the chassis designers.
Were there difficulties in developing the 2017 model?
Noda In the summer, we conducted post-race testing with the riders. We would ask them to ride bikes with different specifications to gain feedback on the changes we made. It’s a test, so I rode the same track as the riders, which gave me a real understanding of what the riders said, and how the surface felt. In reducing the "too high" feeling, not every aspect could be captured by data, which made the task time-consuming. We could have compromised, but we were determined to find the cause. Rallies are long. Compromise leads to fatigue, which leads to rider errors. It was a problem we would have to solve by improving the bike. We used images with the riders crossing the same path repeatedly, studying their movement. If it looked like the rider was compensating for some reason, we would talk with them to identify the cause, and change the settings. The bike as a result had evolved, and our confidence in the bike grew.
What are your ambitions for the 2017 Dakar, and what would you say to the fans?
Sasaki The more we experience the Dakar Rally, the more we understand its challenges and its magic. You never know what will happen. We also learned that the battles with our rivals are on the edge. Keep the speed, raise the durability. Faster. That’s what makes a faster bike. Through our development and test-racing this year, our team is definitely gaining in strength. We hope everybody will support us, as we’re aiming for the top.